Contacts between people, equipment and vehicles prior and during outbreak situations are critical to determine the possible source of infection of a farm. Hired laborers are known to play a big role in interconnecting farms. Once a farm is infected, culling entire flock is the only option to prevent further spreading with devastating consequences for the industry.
In this paper, based on the HPAI outbreak in Holland 2003, the researchers found that 32 farms hired external labor of which seven accessed other poultry on the same day.
However, they were not the only ‘connectors’ as some (twelve) farmers also reported themselves helping on other poultry farms.
Furthermore, 27 farms had family members visiting poultry or poultry-related businesses of which nine entered poultry houses during those visits. The other enhancing factor of farm interconnections was the reported ownership of multiple locations for ten of the interviewed farms and the reported on-premises sale of farm products on one pullet and eight layer farms.
Also worth mentioning is the practice of a multiple age system reported on eight of the interviewed farms as this may increase the risk of infecting remaining birds when off-premises poultry movements occur.
AI viruses may be introduced into poultry from reservoirs such as aquatic wild birds but the mechanisms of their subsequent spread are partially unclear. Transmission of the virus through movements of humans (visitors, servicemen and farm personnel), vectors (wild birds, rodents, insects), air- (and dust-) related routes and other fomites (e.g., delivery trucks, visitors’ clothes and farm equipment) have all been hypothesized.
It is therefore hypothesized that the risk of introducing the virus to a farm is determined by the farm’s neighborhood characteristics, contact structure and its biosecurity practices.
On the one hand, neighborhood characteristics include factors such as the presence of water bodies (accessed by wild birds), the density of poultry farms (together with the number and type of birds on these farms) and poultry-related businesses and the road network. The use of manure in the farm’s vicinity is also deemed to be risky.
On the other hand, contact structure risk factors include the nature and frequency of farm visits. Therefore, a detailed analysis of the contact structure, including neighborhood risks, and biosecurity practices across different types of poultry farms and poultry-related businesses helps the improvement of intervention strategies, biosecurity protocols and adherence to these, as well as contact tracing protocols.
Farmers’ perception of visitor- and neighborhood-associated risks of virus spread is also important due to its relevance to adherence with biosecurity protocols, to contact tracing and to communicating advice to them.
Per contact probability of infection by Highly Pathogenic Avian InfluenzaHarm Kiezebrink
Estimates of the per-contact probability of transmission between farms of Highly Pathogenic Avian Influenza virus of H7N7 subtype during the 2003 epidemic in the Netherlands are important for the design of better control and biosecurity strategies.
We used standardized data collected during the epidemic and a model to extract data for untraced contacts based on the daily number of infectious farms within a given distance of a susceptible farm.
With these data, the ‘maximum likelihood estimation’ approach was used to estimate the transmission probabilities by the individual contact types, both traced and untraced.
The outcomes were validated against literature data on virus genetic sequences for outbreak farms. The findings highlight the need to
1) Understand the routes underlying the infections without traced contacts and
2) To review whether the contact-tracing protocol is exhaustive in relation to all the farm’s day-to-day activities and practices.
Human-to-Human transmission of H7H7 in Holland 2003Harm Kiezebrink
The outbreak of highly pathogenic avian influenza A virus subtype H7N7 started at the end of February, 2003, in commercial poultry farms in the Netherlands. In this study, published in The Lancet in 2004, it is noted that an unexpectedly high number of transmissions of avian influenza A virus subtype H7N7 to people directly involved in handling infected poultry, providing evidence for person-to-person transmission.
Although the risk of transmission of these viruses to humans was initially thought to be low, an outbreak investigation was launched to assess the extent of transmission of influenza A virus subtype H7N7 from chickens to humans.
453 people had health complaints—349 reported conjunctivitis, 90 had influenza-like illness, and 67 had other complaints. We detected A/H7 in conjunctival samples from 78 (26·4%) people with conjunctivitis only, in five (9·4%) with influenza-like illness and conjunctivitis, in two (5·4%) with influenza-like illness only, and in four (6%) who reported other symptoms. Most positive samples had been collected within 5 days of symptom onset. A/H7 infection was confirmed in three contacts (of 83 tested), one of whom developed influenza-like illness. Six people had influenza A/H3N2 infection. After 19 people had been diagnosed with the infection, all workers received mandatory influenza virus vaccination and prophylactic treatment with oseltamivir. More than half (56%) of A/H7 infections reported here arose before the vaccination and treatment programme.
Spatial, temporal and genetic dynamics of H5N1 in chinaHarm Kiezebrink
The spatial spread of H5N1 avian influenza, significant ongoing mutations, and long-term persistence of the virus in some geographic regions has had an enormous impact on the poultry industry and presents a serious threat to human health.
This study revealed two different transmission modes of H5N1 viruses in China, and indicated a significant role of poultry in virus dissemination. Furthermore, selective pressure posed by vaccination was found in virus evolution in the country.
Phylogenetic analysis, geospatial techniques, and time series models were applied to investigate the spatiotemporal pattern of H5N1 outbreaks in China and the effect of vaccination on virus evolution.
Results showed obvious spatial and temporal clusters of H5N1 outbreaks on different scales, which may have been associated with poultry and wild-bird transmission modes of H5N1 viruses. Lead–lag relationships were found among poultry and wild-bird outbreaks and human cases. Human cases were preceded by poultry outbreaks, and wild-bird outbreaks were led by human cases.
Each clade has gained its own unique spatiotemporal and genetic dominance. Genetic diversity of the H5N1 virus decreased significantly between 1996 and 2011; presumably under strong selective pressure of vaccination. Mean evolutionary rates of H5N1 virus increased after vaccination was adopted in China.
Avian influenza virus-infected poultry can release a large amount of virus-contaminated droppings that serve as sources of infection for susceptible birds. Much research so far has focused on virus spread within flocks. However, as fecal material or manure is a major constituent of airborne poultry dust, virus-contaminated particulate matter from infected flocks may be dispersed into the environment.
This study, demonstrates the presence of airborne influenza virus RNA downwind from buildings holding LPAI-infected birds, and the observed correlation between field data on airborne poultry and livestock associated microbial exposure and the OPS-ST model. These findings suggest that geographical estimates of areas at high risk for human and animal exposure to airborne influenza virus can be modeled during an outbreak, although additional field measurements are needed to validate this proposition. In addition, the outdoor detection of influenza virus contaminated airborne dust during outbreaks in poultry suggests that practical measures can assist in the control of future influenza outbreaks.
In general, exposure to airborne influenza virus on commercial poultry farms could be reduced both by minimizing the initial generation of airborne particles and implementing methods for abatement of particles once generated. As an example, emergency mass culling of poultry using a foam blanket over the birds instead of labor-intensive whole-house gassing followed by ventilation reduces both exposure of cullers and dispersion of contaminated dust into the environment, contributing to the control of influenza outbreaks.
In this paper various bird welfare aspects related to avian influenza and other contagious diseases are discussed.
Disease outbreaks will, apart from the obvious direct effects on bird health, and thereby their wellbeing, also indirectly influence the welfare of the birds. For example, restrictions on outdoor access for free-range poultry may be imposed, and vaccination or testing schemes may lead to handling or sampling procedures that are stressful to the birds.
At the same time, the immediate risk of a disease outbreak may lead to improved biosecurity measures on farms, which may in turn decrease the risk of other diseases entering the premises, thus resulting in improved bird health and welfare.
The 3 P’s of avian influenza Prevent, Plan, PracticeHarm Kiezebrink
Avian Influenza has become endemic in many parts of the word. In it's current form it has been around since 1997 and although thy virus types have changed, emergency response, management & control are still a hot issue. In this article published in 2006 in the US magazine Poultry Perspectives, the subject what to do during crisis situations is presented. The conclusions are still valid today and may help to prevent large-scale outbreaks
H5N8 virus dutch outbreak (2014) linked to sequences of strains from asiaHarm Kiezebrink
Genetic analysis of influenza A(H5N8) virus from the Netherlands indicates that the virus probably was spread by migratory wild birds from Asia, possibly through overlapping flyways and common breeding sites in Siberia. In addition to the outbreak in the Netherlands, several other outbreaks of HPAI (H5N8) virus infections were reported in Europe at the end of 2014 after exponentially increasing deaths occurred in chicken and turkey flocks.
Genetic sequences submitted to the EpiFlu database indicated that the viruses from Europe showed a strong similarity to viruses isolated earlier in 2014 in South Korea, China, and Japan. An H5N8 virus isolated from a wigeon in Russia in September 2014 is located in the phylogenetic tree near the node of all sequences for H5N8 viruses from Europe.
In regard to time, this location fits the hypothesized route of H5N8 virus introduction into Europe. Furthermore, for several reasons, it is highly likely that the introduction of HPAI (H5N8) virus into the indoor-layer farm in the Netherlands occurred via indirect contact.
First, despite intensive monitoring, H5N8 viruses have never been detected in commercial poultry or wild birds in the Netherlands.
Second, when the virus was detected, the Netherlands had no direct trade contact with other European countries or Asia that might explain a route of introduction.
Third, because of the severity of disease in galliforms, outbreaks of H5N8 in the Netherlands before November 2014 would have been noticed.
Dossier transmission: Transmission of Avian Influenza Virus to DogsHarm Kiezebrink
Avian influenza was found in a dog on a farm in South Gyeongsang Province amid growing concerns that the disease could spread to other animals, officials the Ministry of Agriculture, Food and Rural Affairs said. The dog ― one of three at a duck farm in Goseong-gun, South Gyeongsang Province ― had antigens for the highly pathogenic H5N8 strain of bird flu, the Ministry of Agriculture, Food and Rural Affairs said. The disease affected the farm on Jan. 23.
Since the first case of a dog being infected with the poultry virus in March 2014, there have been 55 dogs found with antibodies to the bird flu virus. The antibody means the immune system of the dogs eliminated the virus. This is the first time bird flu has been found in a dog in Korea through the detection of antigens.
“None of these dogs had shown symptoms. No antigens or antibodies for the virus were found in the two other dogs, which means that dog-to-dog transmission is unlikely to have happened,” quarantine officials said.
The ministry suspected that the dog may have eaten infected animals at the farm. All poultry and dogs at the concerned farm were slaughtered as part of the preventive measures right after the farm was reported to have been infected with the disease, officials said.
Meanwhile, quarantine officials rejected the possibility of viral transmission to humans. According to the ministry’s report, about 450 workers at infected farms across the country had been given an antigen test, with none showing signs of infection. None of Korea’s 20,000 farm workers have reported any symptoms so far, officials added.
“It is thought that infected dogs do not show symptoms of the disease as they are naturally resistant to bird flu,” the ministry said. Meanwhile, the Agriculture Ministry has toughened the quarantine measures in Goseong-gun. The region is a frequented by migratory birds, which are suspected to have spread the viral disease.
Per contact probability of infection by Highly Pathogenic Avian InfluenzaHarm Kiezebrink
Estimates of the per-contact probability of transmission between farms of Highly Pathogenic Avian Influenza virus of H7N7 subtype during the 2003 epidemic in the Netherlands are important for the design of better control and biosecurity strategies.
We used standardized data collected during the epidemic and a model to extract data for untraced contacts based on the daily number of infectious farms within a given distance of a susceptible farm.
With these data, the ‘maximum likelihood estimation’ approach was used to estimate the transmission probabilities by the individual contact types, both traced and untraced.
The outcomes were validated against literature data on virus genetic sequences for outbreak farms. The findings highlight the need to
1) Understand the routes underlying the infections without traced contacts and
2) To review whether the contact-tracing protocol is exhaustive in relation to all the farm’s day-to-day activities and practices.
Human-to-Human transmission of H7H7 in Holland 2003Harm Kiezebrink
The outbreak of highly pathogenic avian influenza A virus subtype H7N7 started at the end of February, 2003, in commercial poultry farms in the Netherlands. In this study, published in The Lancet in 2004, it is noted that an unexpectedly high number of transmissions of avian influenza A virus subtype H7N7 to people directly involved in handling infected poultry, providing evidence for person-to-person transmission.
Although the risk of transmission of these viruses to humans was initially thought to be low, an outbreak investigation was launched to assess the extent of transmission of influenza A virus subtype H7N7 from chickens to humans.
453 people had health complaints—349 reported conjunctivitis, 90 had influenza-like illness, and 67 had other complaints. We detected A/H7 in conjunctival samples from 78 (26·4%) people with conjunctivitis only, in five (9·4%) with influenza-like illness and conjunctivitis, in two (5·4%) with influenza-like illness only, and in four (6%) who reported other symptoms. Most positive samples had been collected within 5 days of symptom onset. A/H7 infection was confirmed in three contacts (of 83 tested), one of whom developed influenza-like illness. Six people had influenza A/H3N2 infection. After 19 people had been diagnosed with the infection, all workers received mandatory influenza virus vaccination and prophylactic treatment with oseltamivir. More than half (56%) of A/H7 infections reported here arose before the vaccination and treatment programme.
Spatial, temporal and genetic dynamics of H5N1 in chinaHarm Kiezebrink
The spatial spread of H5N1 avian influenza, significant ongoing mutations, and long-term persistence of the virus in some geographic regions has had an enormous impact on the poultry industry and presents a serious threat to human health.
This study revealed two different transmission modes of H5N1 viruses in China, and indicated a significant role of poultry in virus dissemination. Furthermore, selective pressure posed by vaccination was found in virus evolution in the country.
Phylogenetic analysis, geospatial techniques, and time series models were applied to investigate the spatiotemporal pattern of H5N1 outbreaks in China and the effect of vaccination on virus evolution.
Results showed obvious spatial and temporal clusters of H5N1 outbreaks on different scales, which may have been associated with poultry and wild-bird transmission modes of H5N1 viruses. Lead–lag relationships were found among poultry and wild-bird outbreaks and human cases. Human cases were preceded by poultry outbreaks, and wild-bird outbreaks were led by human cases.
Each clade has gained its own unique spatiotemporal and genetic dominance. Genetic diversity of the H5N1 virus decreased significantly between 1996 and 2011; presumably under strong selective pressure of vaccination. Mean evolutionary rates of H5N1 virus increased after vaccination was adopted in China.
Avian influenza virus-infected poultry can release a large amount of virus-contaminated droppings that serve as sources of infection for susceptible birds. Much research so far has focused on virus spread within flocks. However, as fecal material or manure is a major constituent of airborne poultry dust, virus-contaminated particulate matter from infected flocks may be dispersed into the environment.
This study, demonstrates the presence of airborne influenza virus RNA downwind from buildings holding LPAI-infected birds, and the observed correlation between field data on airborne poultry and livestock associated microbial exposure and the OPS-ST model. These findings suggest that geographical estimates of areas at high risk for human and animal exposure to airborne influenza virus can be modeled during an outbreak, although additional field measurements are needed to validate this proposition. In addition, the outdoor detection of influenza virus contaminated airborne dust during outbreaks in poultry suggests that practical measures can assist in the control of future influenza outbreaks.
In general, exposure to airborne influenza virus on commercial poultry farms could be reduced both by minimizing the initial generation of airborne particles and implementing methods for abatement of particles once generated. As an example, emergency mass culling of poultry using a foam blanket over the birds instead of labor-intensive whole-house gassing followed by ventilation reduces both exposure of cullers and dispersion of contaminated dust into the environment, contributing to the control of influenza outbreaks.
In this paper various bird welfare aspects related to avian influenza and other contagious diseases are discussed.
Disease outbreaks will, apart from the obvious direct effects on bird health, and thereby their wellbeing, also indirectly influence the welfare of the birds. For example, restrictions on outdoor access for free-range poultry may be imposed, and vaccination or testing schemes may lead to handling or sampling procedures that are stressful to the birds.
At the same time, the immediate risk of a disease outbreak may lead to improved biosecurity measures on farms, which may in turn decrease the risk of other diseases entering the premises, thus resulting in improved bird health and welfare.
The 3 P’s of avian influenza Prevent, Plan, PracticeHarm Kiezebrink
Avian Influenza has become endemic in many parts of the word. In it's current form it has been around since 1997 and although thy virus types have changed, emergency response, management & control are still a hot issue. In this article published in 2006 in the US magazine Poultry Perspectives, the subject what to do during crisis situations is presented. The conclusions are still valid today and may help to prevent large-scale outbreaks
H5N8 virus dutch outbreak (2014) linked to sequences of strains from asiaHarm Kiezebrink
Genetic analysis of influenza A(H5N8) virus from the Netherlands indicates that the virus probably was spread by migratory wild birds from Asia, possibly through overlapping flyways and common breeding sites in Siberia. In addition to the outbreak in the Netherlands, several other outbreaks of HPAI (H5N8) virus infections were reported in Europe at the end of 2014 after exponentially increasing deaths occurred in chicken and turkey flocks.
Genetic sequences submitted to the EpiFlu database indicated that the viruses from Europe showed a strong similarity to viruses isolated earlier in 2014 in South Korea, China, and Japan. An H5N8 virus isolated from a wigeon in Russia in September 2014 is located in the phylogenetic tree near the node of all sequences for H5N8 viruses from Europe.
In regard to time, this location fits the hypothesized route of H5N8 virus introduction into Europe. Furthermore, for several reasons, it is highly likely that the introduction of HPAI (H5N8) virus into the indoor-layer farm in the Netherlands occurred via indirect contact.
First, despite intensive monitoring, H5N8 viruses have never been detected in commercial poultry or wild birds in the Netherlands.
Second, when the virus was detected, the Netherlands had no direct trade contact with other European countries or Asia that might explain a route of introduction.
Third, because of the severity of disease in galliforms, outbreaks of H5N8 in the Netherlands before November 2014 would have been noticed.
Dossier transmission: Transmission of Avian Influenza Virus to DogsHarm Kiezebrink
Avian influenza was found in a dog on a farm in South Gyeongsang Province amid growing concerns that the disease could spread to other animals, officials the Ministry of Agriculture, Food and Rural Affairs said. The dog ― one of three at a duck farm in Goseong-gun, South Gyeongsang Province ― had antigens for the highly pathogenic H5N8 strain of bird flu, the Ministry of Agriculture, Food and Rural Affairs said. The disease affected the farm on Jan. 23.
Since the first case of a dog being infected with the poultry virus in March 2014, there have been 55 dogs found with antibodies to the bird flu virus. The antibody means the immune system of the dogs eliminated the virus. This is the first time bird flu has been found in a dog in Korea through the detection of antigens.
“None of these dogs had shown symptoms. No antigens or antibodies for the virus were found in the two other dogs, which means that dog-to-dog transmission is unlikely to have happened,” quarantine officials said.
The ministry suspected that the dog may have eaten infected animals at the farm. All poultry and dogs at the concerned farm were slaughtered as part of the preventive measures right after the farm was reported to have been infected with the disease, officials said.
Meanwhile, quarantine officials rejected the possibility of viral transmission to humans. According to the ministry’s report, about 450 workers at infected farms across the country had been given an antigen test, with none showing signs of infection. None of Korea’s 20,000 farm workers have reported any symptoms so far, officials added.
“It is thought that infected dogs do not show symptoms of the disease as they are naturally resistant to bird flu,” the ministry said. Meanwhile, the Agriculture Ministry has toughened the quarantine measures in Goseong-gun. The region is a frequented by migratory birds, which are suspected to have spread the viral disease.
Outbreak of High Patogen Avian Influenza H5N8 in GermanyHarm Kiezebrink
Germany has reported an outbreak of highly pathogenic avian influenza, H5N8 in fattening turkeys in North East Germany
(Mecklenburg - Western Pomerania). Increased mortality was observed in one of the six sheds of 15 week old birds for fattening (total number of turkeys on the premises ~ 31,000 of which each shed contained 5,000).
Deadly H5N1 birdflu needs just five mutations to spread easily in peopleHarm Kiezebrink
Reference: Phys.org. 15 Apr 2014. Dutch researchers have found that the virus needs only five favorable gene mutations to become transmissible through coughing or sneezing, like regular flu viruses.
World health officials have long feared that the H5N1 virus will someday evolve a knack for airborne transmission, setting off a devastating pandemic. While the new study suggests the mutations needed are relatively few, it remains unclear whether they're likely to happen outside the laboratory.
Supplementary information wind mediated transmission HPAIHarm Kiezebrink
A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.
In this generic overview, you will find the date used in the publication “Modelling the Wind-Borne Spread of Highly Pathogenic Avian Influenza Virus between Farms”, published February 2012 (http://n2gf.com/?p=2377). For the outbreak of avian influenza A(H7N7) in the Netherlands in 2003, much data are available. The overview gives a description of the data used in the analyses of the mentioned publication:
Epidemiological data
There were 5360 poultry farms in the Netherlands in 2003, for all of which geographical information x is available. For 1531 farms the flocks were culled, for all of these the date of culling Tcull is known. For 227 of the 241 infected farms the date of infection tinf has been estimated, based on mortality data. The remaining 14 farms are hobby farms, defined as farms with less than 300 animals, for which no mortality data are available.
The geographic and temporal data together have previously been used to estimate the critical farm density, i.e. above what density of farms outbreaks are can occur.
Genetic data
The HA, NA and PB2 genes of viral samples from 231 farms have previously been sequenced. Sequence data RNA can be found in the GISAID database under accession numbers EPI ISL 68268-68352, EPI ISL 82373-82472 and EPI ISL 83984-84031. These data have previously been used to give general characteristics of the outbreak, to reconstruct the transmission tree and to assess the public health threat due to mutations of the virus in the animal host.
Meteorological data
Available meteorological data include wind speed wv and direction wdir (with a ten degree precision) and the fraction of time r without precipitation for every hour of every day of the outbreak, measured at five weather stations close to the infected farms. These data are available from the Royal Dutch Meteorological Institute at www.knmi.nl.
Different environmental drivers of H5N1 outbreaks in poultry and wild birdsHarm Kiezebrink
Different environmental drivers operate on HPAI H5N1 outbreaks in poultry and wild birds in Europe. The probability of HPAI H5N1 outbreaks in poultry increases in areas with a higher human population density and a shorter distance to lakes or wetlands.
This reflects areas where the location of farms or trade areas and habitats for wild birds overlap. In wild birds, HPAI H5N1 outbreaks mostly occurred in areas with increased NDVI and lower elevations, which are typically areas where food and shelter for wild birds are available. The association with migratory flyways has also been found in the intra-continental spread of the low pathogenic avian influenza virus in North American wild birds. These different environmental drivers suggest that different spread mechanisms operate.
Disease might spread to poultry via both poultry and wild birds, through direct (via other birds) or indirect (e.g. via contaminated environment) infection. Outbreaks in wild birds are mainly caused by transmission via wild birds alone, through sharing foraging areas or shelters. These findings are in contrast with a previous study, which did not find environmental differences between disease outbreaks in poultry and wild birds in Europe.
Modelling wind-borne spread of HPAI between farms (2012)Harm Kiezebrink
To understand the risks of spreading contaminated materials caused by stable gassing, a quantitative understanding of the spread of contaminated farm dust between locations is a prerequisite for obtaining much-needed insight into one of the possible mechanisms of disease spread between farms.
The researchers Amos Ssematimba, Thomas J. Hagenaars, Mart C. M. de Jong of the Dutch Department of Epidemiology, Crisis Organization and Diagnostics, Central Veterinary Institute (CVI) part of Wageningen University and Research Centre, Lelystad, The Netherlands, and Quantitative Veterinary Epidemiology, Department of Animal Sciences, Wageningen University, Wageningen, The Netherland developed a model to calculate the quantity of contaminated farm-dust particles deposited at various locations downwind of a source farm and apply the model to assess the possible contribution of the wind-borne route to the transmission of Highly Pathogenic Avian Influenza virus (HPAI) during the 2003 epidemic in the Netherlands.
The model is obtained from a Gaussian Plume Model by incorporating the dust deposition process, pathogen decay, and a model for the infection process on exposed farms.
Using poultry- and avian influenza-specific parameter values we calculate the distance-dependent probability of between-farm transmission by this route.
A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.
Spatio temporal dynamics of global H5N1 outbreaks match bird migration patternsHarm Kiezebrink
The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant pandemic threat and a serious public health risk.
An efficient surveillance and disease control system relies on the understanding of the dispersion patterns and spreading mechanisms of the virus. A space-time cluster analysis of H5N1 outbreaks was used to identify spatio-temporal patterns at a global scale and over an extended period of time.
Potential mechanisms explaining the spread of the H5N1 virus, and the role of wild birds, were analyzed. Between December 2003 and December 2006, three global epidemic phases of H5N1 influenza were identified.
These H5N1 outbreaks showed a clear seasonal pattern, with a high density of outbreaks in winter and early spring (i.e., October to March). In phase I and II only the East Asia Australian flyway was affected. During phase III, the H5N1 viruses started to appear in four other flyways: the Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and the East Africa West Asian flyway.
Six disease cluster patterns along these flyways were found to be associated with the seasonal migration of wild birds. The spread of the H5N1 virus, as demonstrated by the space-time clusters, was associated with the patterns of migration of wild birds. Wild birds may therefore play an important role in the spread of H5N1 over long distances.
Disease clusters were also detected at sites where wild birds are known to overwinter and at times when migratory birds were present. This leads to the suggestion that wild birds may also be involved in spreading the H5N1 virus over short distances.
Twenty-two researchers from labs across the world submitted a letter to Nature and Science yesterday detailing their proposed “gain-of-function” research on the avian influenza virus H7N9.
Their work would genetically engineer H7N9 to make it both more virulent and more readily transmissible person-to-person. The research sounds controversial, not the least because one of the scientists involved is Dr. Ron Fouchier, whose on gain-of-function work on H5N1 ingnited furious debate over what should research should and shouldn’t be published.
However, there is a very real possibility that H7N9 will naturally mutate to transmit effectively between people. We already know that the virus is just a single amino acid mutation away from becoming easily transmissible between people. Indeed, news of the first confirmed case of such transmission was published in the British Medical Journal this week.
With a 60% fatality rate and a completely naive global population, the results would be catastrophic. The proposed research would give us an idea of potential pandemic scenarios, giving us a head start on potential vaccine and antiviral development.
It may be controversial, but it’s absolutely necessary.
Influenza in birds is caused by infection with viruses of the family Orthomyxoviridae placed in the genus influenza virus A. Influenza A viruses are the only orthomyxoviruses known to naturally affect birds. Many species of birds have been shown to be susceptible to infection with influenza A viruses; aquatic birds form a major reservoir of these viruses, and the overwhelming majority of isolates have been of low pathogenicity (low virulence) for chickens and turkeys. Influenza A viruses have antigenically related nucleocapsid and matrix proteins, but are classified into subtypes on the basis of their haemagglutinin (H) and neuraminidase (N) antigens (World Health Organization Expert Committee, 1980). At present, 16 H subtypes (H1–H16) and 9 N subtypes (N1–N9) are recognised with proposed new subtypes (H17, H18) for influenza A viruses from bats in Guatemala (Swayne et al., 2013; Tong et al., 2012; 2013). To date, naturally occurring highly pathogenic influenza A viruses that produce acute clinical disease in chickens, turkeys and other birds of economic importance have been associated only with the H5 and H7 subtypes. Most viruses of the H5 and H7 subtype isolated from birds have been of low pathogenicity for poultry. As there is the risk of a H5 or H7 virus of low pathogenicity (H5/H7 low pathogenicity avian influenza [LPAI]) becoming highly pathogenic by mutation, all H5/H7 LPAI viruses from poultry are notifiable to OIE. In addition, all high pathogenicity viruses from poultry and other birds, including wild birds, are notifiable to the OIE.
FLI Seminar on different response strategies: Stamping out or NeutralizationHarm Kiezebrink
During this spring, American poultry producers are losing birds by the millions, due to the High Pathogenic Avian Influenza outbreaks on factory farms. USDA APHIS applied the stamping out strategy in an attempt to prevent the flu from spreading.
With stamping out as the highest priority of the response strategy, large numbers of responders are involved. With in average almost 1 million caged layers per farm in Iowa, there is hardly any room for a proper bio security training for these responders. And existing culling techniques had insufficient capacity, the authorities had to decide to apply drastic techniques like macerating live birds in order to take away the source of virus reproduction.
This strategy didn't work; on the contrary. Instead of slowing down the spreading of the virus, the outbreaks continue to reoccur and have caused death and destruction in 15 USA states, killing almost 50 million birds on mote than 220infected commercial poultry farms, all within a very small time frame.
The question is whether the priority of the response strategy should be on neutralizing the transmission routes instead of on stamping out infections after they occur. All indicators currently point out into the direction that the industry should prioritize on environmental drivers: the connection between outbreaks and wild ducks; wind-mediated transmission; pre-contact probability; on-farm bio security; transmission via rodents etc.
Once the contribution of each transmission route has been determined, a revolutionary new response strategy can be developed based on the principle of neutralizing transmission routes. Neutralizing risks means that fully new techniques need to be developed, based on culling the animals without human – to – animal contact; integrating detergent application into the culling operations; combining culling & disposal into one activity.
This new response strategy will be the main subject of the FLI Animal Welfare and Disease Control Seminar, organized at September 23, 2015 in Celle, Germany
In 2007, USAID launched a worldwide program to battle outbreaks of Avian Influenza under the name STOP AI: Stamping Out Pandemic & Avian Influenza.
This program was one of the largest Training of trainer programs on Avian Influenza of its kind, with training programs conducted in more than 40 countries.
The training manual contains valuable training materials, presentations, background information and references on various subjects:
Module 1 – Overview of Avian Influenza
Module 2 – National Preparedness & Response Plans for HPAI
Module 3 – OIE Avian Influenza Standards and FAO Emergency Prevention System
Module 4 – Public Health and Occupational Safety
Module 5 – Animal Surveillance
Module 6 – Sample Collection and Transport
Module 7 – GIS and Outbreak Mapping
Module 8 – Biosecurity
Module 9 – Introduction to Outbreak Response
Module 10 – Depopulation, Disposal, and Decontamination
Module 11 – Recovery Options.
This training course was intended for animal and human health experts who have limited experience with avian influenza, but who do have field experience with other animal, zoonotic, or infectious diseases. This course includes modules on avian influenza virology, epidemiology, response, and recovery.
Avian influenza is usually an inapparent or nonclinical
viral infection of wild birds that is caused by a group of
viruses known as type A influenzas. These viruses are maintained in wild birds by fecal-oral routes of transmission. This virus changes rapidly in nature by mixing of its genetic components to form slightly different virus subtypes. Avian influenza is caused by this collection of slightly different viruses rather than by a single virus type. The virus subtypes are identified and classified on the basis of two broad types of antigens, hemagglutinan (H) and neuraminidase (N); 15 H and 9 N antigens have been identified among all of the known type A influenzas.
The misunderstood epidemiological determinants of covid 19, problems and solu...Bhoj Raj Singh
COVID-19, a viral disease, fought with political means for socio-economic gains, will keep on haunting humanity for long. Without doing any epidemiological study on COVID-19 we have determined its modulators and determinants not to win over COVID-19 but to create misunderstanding to persist for long in inquisitive minds to blur the vision for novel inventions. This presentation deals with COVID-19 in general and misunderstood disease determinants in particular to suggest possible means to win over the disease. As the tip of COVID-19 iceberg is illusion and reality unknown, thus the struggle is endless.
Epidemiological studies on avian influenza in behera province, egypt publishe...hany shita
The current study was conducted to monitor avian influenza A viruses using commercially available
rapid antigen detection test procedures in small-scale commercial poultry farms (sector III) in selected districts
of Behera province,Egypt.
A Retrospective Disease Surveillance Based Approach in the Investigation and ...Stephen Olubulyera
A Retrospective Disease Surveillance Based Approach in the Investigation and Linkage of Human Brucellosis to Animal Sources: One Health Approach Complementary Strategy Applicable in Nomadic Pastoralism, a Case Study of Turkana County, Kenya.
Outbreak of High Patogen Avian Influenza H5N8 in GermanyHarm Kiezebrink
Germany has reported an outbreak of highly pathogenic avian influenza, H5N8 in fattening turkeys in North East Germany
(Mecklenburg - Western Pomerania). Increased mortality was observed in one of the six sheds of 15 week old birds for fattening (total number of turkeys on the premises ~ 31,000 of which each shed contained 5,000).
Deadly H5N1 birdflu needs just five mutations to spread easily in peopleHarm Kiezebrink
Reference: Phys.org. 15 Apr 2014. Dutch researchers have found that the virus needs only five favorable gene mutations to become transmissible through coughing or sneezing, like regular flu viruses.
World health officials have long feared that the H5N1 virus will someday evolve a knack for airborne transmission, setting off a devastating pandemic. While the new study suggests the mutations needed are relatively few, it remains unclear whether they're likely to happen outside the laboratory.
Supplementary information wind mediated transmission HPAIHarm Kiezebrink
A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.
In this generic overview, you will find the date used in the publication “Modelling the Wind-Borne Spread of Highly Pathogenic Avian Influenza Virus between Farms”, published February 2012 (http://n2gf.com/?p=2377). For the outbreak of avian influenza A(H7N7) in the Netherlands in 2003, much data are available. The overview gives a description of the data used in the analyses of the mentioned publication:
Epidemiological data
There were 5360 poultry farms in the Netherlands in 2003, for all of which geographical information x is available. For 1531 farms the flocks were culled, for all of these the date of culling Tcull is known. For 227 of the 241 infected farms the date of infection tinf has been estimated, based on mortality data. The remaining 14 farms are hobby farms, defined as farms with less than 300 animals, for which no mortality data are available.
The geographic and temporal data together have previously been used to estimate the critical farm density, i.e. above what density of farms outbreaks are can occur.
Genetic data
The HA, NA and PB2 genes of viral samples from 231 farms have previously been sequenced. Sequence data RNA can be found in the GISAID database under accession numbers EPI ISL 68268-68352, EPI ISL 82373-82472 and EPI ISL 83984-84031. These data have previously been used to give general characteristics of the outbreak, to reconstruct the transmission tree and to assess the public health threat due to mutations of the virus in the animal host.
Meteorological data
Available meteorological data include wind speed wv and direction wdir (with a ten degree precision) and the fraction of time r without precipitation for every hour of every day of the outbreak, measured at five weather stations close to the infected farms. These data are available from the Royal Dutch Meteorological Institute at www.knmi.nl.
Different environmental drivers of H5N1 outbreaks in poultry and wild birdsHarm Kiezebrink
Different environmental drivers operate on HPAI H5N1 outbreaks in poultry and wild birds in Europe. The probability of HPAI H5N1 outbreaks in poultry increases in areas with a higher human population density and a shorter distance to lakes or wetlands.
This reflects areas where the location of farms or trade areas and habitats for wild birds overlap. In wild birds, HPAI H5N1 outbreaks mostly occurred in areas with increased NDVI and lower elevations, which are typically areas where food and shelter for wild birds are available. The association with migratory flyways has also been found in the intra-continental spread of the low pathogenic avian influenza virus in North American wild birds. These different environmental drivers suggest that different spread mechanisms operate.
Disease might spread to poultry via both poultry and wild birds, through direct (via other birds) or indirect (e.g. via contaminated environment) infection. Outbreaks in wild birds are mainly caused by transmission via wild birds alone, through sharing foraging areas or shelters. These findings are in contrast with a previous study, which did not find environmental differences between disease outbreaks in poultry and wild birds in Europe.
Modelling wind-borne spread of HPAI between farms (2012)Harm Kiezebrink
To understand the risks of spreading contaminated materials caused by stable gassing, a quantitative understanding of the spread of contaminated farm dust between locations is a prerequisite for obtaining much-needed insight into one of the possible mechanisms of disease spread between farms.
The researchers Amos Ssematimba, Thomas J. Hagenaars, Mart C. M. de Jong of the Dutch Department of Epidemiology, Crisis Organization and Diagnostics, Central Veterinary Institute (CVI) part of Wageningen University and Research Centre, Lelystad, The Netherlands, and Quantitative Veterinary Epidemiology, Department of Animal Sciences, Wageningen University, Wageningen, The Netherland developed a model to calculate the quantity of contaminated farm-dust particles deposited at various locations downwind of a source farm and apply the model to assess the possible contribution of the wind-borne route to the transmission of Highly Pathogenic Avian Influenza virus (HPAI) during the 2003 epidemic in the Netherlands.
The model is obtained from a Gaussian Plume Model by incorporating the dust deposition process, pathogen decay, and a model for the infection process on exposed farms.
Using poultry- and avian influenza-specific parameter values we calculate the distance-dependent probability of between-farm transmission by this route.
A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.
Spatio temporal dynamics of global H5N1 outbreaks match bird migration patternsHarm Kiezebrink
The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant pandemic threat and a serious public health risk.
An efficient surveillance and disease control system relies on the understanding of the dispersion patterns and spreading mechanisms of the virus. A space-time cluster analysis of H5N1 outbreaks was used to identify spatio-temporal patterns at a global scale and over an extended period of time.
Potential mechanisms explaining the spread of the H5N1 virus, and the role of wild birds, were analyzed. Between December 2003 and December 2006, three global epidemic phases of H5N1 influenza were identified.
These H5N1 outbreaks showed a clear seasonal pattern, with a high density of outbreaks in winter and early spring (i.e., October to March). In phase I and II only the East Asia Australian flyway was affected. During phase III, the H5N1 viruses started to appear in four other flyways: the Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and the East Africa West Asian flyway.
Six disease cluster patterns along these flyways were found to be associated with the seasonal migration of wild birds. The spread of the H5N1 virus, as demonstrated by the space-time clusters, was associated with the patterns of migration of wild birds. Wild birds may therefore play an important role in the spread of H5N1 over long distances.
Disease clusters were also detected at sites where wild birds are known to overwinter and at times when migratory birds were present. This leads to the suggestion that wild birds may also be involved in spreading the H5N1 virus over short distances.
Twenty-two researchers from labs across the world submitted a letter to Nature and Science yesterday detailing their proposed “gain-of-function” research on the avian influenza virus H7N9.
Their work would genetically engineer H7N9 to make it both more virulent and more readily transmissible person-to-person. The research sounds controversial, not the least because one of the scientists involved is Dr. Ron Fouchier, whose on gain-of-function work on H5N1 ingnited furious debate over what should research should and shouldn’t be published.
However, there is a very real possibility that H7N9 will naturally mutate to transmit effectively between people. We already know that the virus is just a single amino acid mutation away from becoming easily transmissible between people. Indeed, news of the first confirmed case of such transmission was published in the British Medical Journal this week.
With a 60% fatality rate and a completely naive global population, the results would be catastrophic. The proposed research would give us an idea of potential pandemic scenarios, giving us a head start on potential vaccine and antiviral development.
It may be controversial, but it’s absolutely necessary.
Influenza in birds is caused by infection with viruses of the family Orthomyxoviridae placed in the genus influenza virus A. Influenza A viruses are the only orthomyxoviruses known to naturally affect birds. Many species of birds have been shown to be susceptible to infection with influenza A viruses; aquatic birds form a major reservoir of these viruses, and the overwhelming majority of isolates have been of low pathogenicity (low virulence) for chickens and turkeys. Influenza A viruses have antigenically related nucleocapsid and matrix proteins, but are classified into subtypes on the basis of their haemagglutinin (H) and neuraminidase (N) antigens (World Health Organization Expert Committee, 1980). At present, 16 H subtypes (H1–H16) and 9 N subtypes (N1–N9) are recognised with proposed new subtypes (H17, H18) for influenza A viruses from bats in Guatemala (Swayne et al., 2013; Tong et al., 2012; 2013). To date, naturally occurring highly pathogenic influenza A viruses that produce acute clinical disease in chickens, turkeys and other birds of economic importance have been associated only with the H5 and H7 subtypes. Most viruses of the H5 and H7 subtype isolated from birds have been of low pathogenicity for poultry. As there is the risk of a H5 or H7 virus of low pathogenicity (H5/H7 low pathogenicity avian influenza [LPAI]) becoming highly pathogenic by mutation, all H5/H7 LPAI viruses from poultry are notifiable to OIE. In addition, all high pathogenicity viruses from poultry and other birds, including wild birds, are notifiable to the OIE.
FLI Seminar on different response strategies: Stamping out or NeutralizationHarm Kiezebrink
During this spring, American poultry producers are losing birds by the millions, due to the High Pathogenic Avian Influenza outbreaks on factory farms. USDA APHIS applied the stamping out strategy in an attempt to prevent the flu from spreading.
With stamping out as the highest priority of the response strategy, large numbers of responders are involved. With in average almost 1 million caged layers per farm in Iowa, there is hardly any room for a proper bio security training for these responders. And existing culling techniques had insufficient capacity, the authorities had to decide to apply drastic techniques like macerating live birds in order to take away the source of virus reproduction.
This strategy didn't work; on the contrary. Instead of slowing down the spreading of the virus, the outbreaks continue to reoccur and have caused death and destruction in 15 USA states, killing almost 50 million birds on mote than 220infected commercial poultry farms, all within a very small time frame.
The question is whether the priority of the response strategy should be on neutralizing the transmission routes instead of on stamping out infections after they occur. All indicators currently point out into the direction that the industry should prioritize on environmental drivers: the connection between outbreaks and wild ducks; wind-mediated transmission; pre-contact probability; on-farm bio security; transmission via rodents etc.
Once the contribution of each transmission route has been determined, a revolutionary new response strategy can be developed based on the principle of neutralizing transmission routes. Neutralizing risks means that fully new techniques need to be developed, based on culling the animals without human – to – animal contact; integrating detergent application into the culling operations; combining culling & disposal into one activity.
This new response strategy will be the main subject of the FLI Animal Welfare and Disease Control Seminar, organized at September 23, 2015 in Celle, Germany
In 2007, USAID launched a worldwide program to battle outbreaks of Avian Influenza under the name STOP AI: Stamping Out Pandemic & Avian Influenza.
This program was one of the largest Training of trainer programs on Avian Influenza of its kind, with training programs conducted in more than 40 countries.
The training manual contains valuable training materials, presentations, background information and references on various subjects:
Module 1 – Overview of Avian Influenza
Module 2 – National Preparedness & Response Plans for HPAI
Module 3 – OIE Avian Influenza Standards and FAO Emergency Prevention System
Module 4 – Public Health and Occupational Safety
Module 5 – Animal Surveillance
Module 6 – Sample Collection and Transport
Module 7 – GIS and Outbreak Mapping
Module 8 – Biosecurity
Module 9 – Introduction to Outbreak Response
Module 10 – Depopulation, Disposal, and Decontamination
Module 11 – Recovery Options.
This training course was intended for animal and human health experts who have limited experience with avian influenza, but who do have field experience with other animal, zoonotic, or infectious diseases. This course includes modules on avian influenza virology, epidemiology, response, and recovery.
Avian influenza is usually an inapparent or nonclinical
viral infection of wild birds that is caused by a group of
viruses known as type A influenzas. These viruses are maintained in wild birds by fecal-oral routes of transmission. This virus changes rapidly in nature by mixing of its genetic components to form slightly different virus subtypes. Avian influenza is caused by this collection of slightly different viruses rather than by a single virus type. The virus subtypes are identified and classified on the basis of two broad types of antigens, hemagglutinan (H) and neuraminidase (N); 15 H and 9 N antigens have been identified among all of the known type A influenzas.
The misunderstood epidemiological determinants of covid 19, problems and solu...Bhoj Raj Singh
COVID-19, a viral disease, fought with political means for socio-economic gains, will keep on haunting humanity for long. Without doing any epidemiological study on COVID-19 we have determined its modulators and determinants not to win over COVID-19 but to create misunderstanding to persist for long in inquisitive minds to blur the vision for novel inventions. This presentation deals with COVID-19 in general and misunderstood disease determinants in particular to suggest possible means to win over the disease. As the tip of COVID-19 iceberg is illusion and reality unknown, thus the struggle is endless.
Epidemiological studies on avian influenza in behera province, egypt publishe...hany shita
The current study was conducted to monitor avian influenza A viruses using commercially available
rapid antigen detection test procedures in small-scale commercial poultry farms (sector III) in selected districts
of Behera province,Egypt.
A Retrospective Disease Surveillance Based Approach in the Investigation and ...Stephen Olubulyera
A Retrospective Disease Surveillance Based Approach in the Investigation and Linkage of Human Brucellosis to Animal Sources: One Health Approach Complementary Strategy Applicable in Nomadic Pastoralism, a Case Study of Turkana County, Kenya.
Cattle Ticks and Risk Factors Related to Tick Infestation of Livestock in Per...Agriculture Journal IJOEAR
Tick-borne diseases are a global public health problem, particularly in sub-Saharan Africa, where most of the disease is caused by malaria and many other diseases of viral, parasitic or bacterial origin. This study aimed to identify the bovine tick's species in cattle farms and to determine possible risk factors related to tick infestation in Abidjan district and Azaguié commune. Thus, in July 2019, thirteen (13) herds distributed in these localities were visited for tick sampling and to conduct epidemiological investigations. At each visit, ticks were harvested from 15 cattle per herd. All the farms visited were infested with ticks. 96.92% of sampled animals had ticks. A total of 1796 ticks were collected of which 89.42% (1606) were adults, 10.41% (187) were pupae and 0.17% (3) was larvae. Two species of ticks have been identified, Amblyomma variegatum with 25% of the population and Rhipicephalus (Boophilus) microplus with 75%. 96% of the cattle were infested by ticks of the species R. (B.) microplus and 56% of the cattle were infested by ticks of the species A. variegatum. The co-infestation of cattle by the two identified species was 53%. The distribution of the sexes showed that in the species A. variegatum, males were more numerous (13.44% for males and 8.76% for females). However in the species R. (B.) microplus, females were more numerous (5.08% for males and 62.3% for females).The analysis of risk factors associated with tick infestation in cattle has shown that factors such as Undefined parks, Type of pasture, Training in the use of acaricides and Presence of wild animals contribute to major ectoparasite infestations in cattle. Tick samples collected from peri-urban farms in the district of Abidjan and the locality of Azaguié as part of this study, indicate that the relatively recent introduction of the species Rhipicephalus (Boophilus) microplus presents a threat to animal and human health.
Study of the Seroprevalence of Anti-Leptospirosis Antibodies in Subjects in T...IIJSRJournal
Leptospirosis is a tropical and subtropical zoonotic disease culminating as a serious public health problem worldwide, apparently existing as co-infections with various other unrelated diseases, such as malaria. It is caused by spiral bacteria and the main vectors of which are rodents. These bacteria have various survival mechanisms in the environment allowing them to carry out their infectious cycle within their host organisms. The pathophysiological mechanisms pertaining to leptospirosis is still not understood in full and mis or underdiagnosed.
A cross-sectional descriptive study was carried out in three different localities in Niamey where respondents were screened for to demonstrate transmission to humans. Indirect ELISA method as a laboratory diagnostic or screening toll is used by utilizing leptospiral-specific IgG from serum samples of the respondents.
Results from the study showed that 11 people are found to be positive for leptospirosis (with a seroprevalence of 2.75%) with a strong tendency in the slaughterhouse workers which presents a fairly high risk compared to the other localities of the study. Indeed, the different areas/localities of this pilot study do not present the same level of risk because they are not subject to the same risk associated factors. In this vein, we have 87.6% of population exposed to the presence of rats, 48% are in contact with animals, 38.6% live in homes near water and 12.9% go swimming.
This study made it possible, on the one hand, to highlight the transmission of leptospirosis from animals to humans and, on the other hand, to draw attention to the involvement of the various identified risk factors.
Soil-transmitted helminth infections (STH) and schistosomiasis constitute major public health challenges among school‐age children in sub-Saharan Africa. Chemotherapy with the Benzimidazole chemical family is one of the most effective strategies to lower the rates of morbidity and mortality. But now a day anthelmintic resistance in the treatment and control of human helminthes has been reported in different areas in Ethiopia. The objective of this study, therefore, is to assess the efficacy of albendazole (400 mg, manufactured by Khandeiwal Laboratories Pvt. Ltd) currently in use against soil-transmitted helminth infections among school children in many areas of Ethiopia. A total of 180 elementary school children were chosen using random sampling technique. Each student was instructed to submit fresh stool specimen. Formal ether concentration technique and Kato-Katz method were done at the study sites and Aksum University, laboratory of Department of Biology and Biotechnology. Among the total study children, 170 submitted fresh stool samples giving a response rate of 96.77%. The overall prevalence of helminth infection was 66.7 % (Adiet), 67.9% (Adwa) and 51.7% (Aksum). In all the study sites albendazole was effective against most soil-transmitted helminthes, with cure rate > 85%, and egg reduction rate >90%. However, it was less effective against Trichuris trichiura with cure rate 58.5% and 57.9% at Adiet and Adwa, respectively. Therefore, due attention should be given with regard to treating helminth positive individuals together with intense environmental sanitation to curb the burden of helminth infection and alternative chemotherapy against Trichuris trichiura should be supplied to the study areas.
Hundred samples viz. urine, blood, wound, pus and sputum collected from different patients were found to harbour Pseudomonas aeruginosa (P. aeruginosa) (27%) with a maximum isolation from wound samples (33.33%) and minimum from blood samples (11.11%). The degree of resistance of P. aeruginosa isolates to different antibiotics like Ceftazidime (30µg), Amikacin (30µg), Imipenem (10µg), Ciprofloxacin (30µg), Tetracycline (30µg), Gentamicin (10µg), Norfloxacin (10µg), Penicillin (30µg), Chloramphenicol (30µg), and Ofloxacin (5µg) varied from 56% to 100%. Antiseptics i.e. Betadine and Dettol were found to be more effective against the MDR strain of P. aeruginosa at the dilutions of 10-1 and 10-2. Duration of the disease and hospitalization duration, evaluated as risk factors for P. aeruginosa colonization were found to be statistically significant while age and gender were found to be statistically non- significant. The incidence of multidrug resistance of P. aeruginosa is increasing fast due to the frequent use of antibiotics and antiseptics, which are used extensively in hospitals and healthcare centers, therefore it is a need to develop alternative antimicrobial agents for the treatment of infectious diseases.
Key-words- Antibiotic, Antiseptic, Betadine and Dettol, Disinfectants, P. aeruginosa
Prevalence of Intestinal Parasitic Infections among Patients Attended to Alri...CrimsonpublishersCJMI
Prevalence of Intestinal Parasitic Infections among Patients Attended to Alribat University hospital, Khartoum State, Sudan, 2017 by Mohammed HMN in Cohesive Journal of Microbiology & Infectious Disease
Retrospective and Prospective Studies of Gastro-Intestinal Helminths of Human...theijes
A five-year retrospective and one-year prospective studies of gastrointestinal (GIT) helminths was carried out in humans and dogs in Makurdi, Nigeria. Data from 534 individuals presented at the Federal Medical Centre (FMC) and 103 faecal samples from dogs at the Veterinary Teaching Hospital (VTH), University of Agriculture, Makurdi from 2007 to 2014 were used. The overall prevalence of zoonotic GIT helminths in humans was 76.21% (407/534) and 56.31% (58/103) in dogs. The differences in the prevalences in humans based on sex,ethnicity and age were not statistically significant (χ2 , P< 0.05). However, the test of individual factor (coefficient) on GIT helminthes in humans showed that hookworms prevalence was dependent on age (P = 0.001), Ascaris lumbricoides was dependent on ethnicity and age (P = 0.000 and 0.005), Taenia spp. prevalence was dependent on age and sex (P = 0.007 and 0.005), and Strongyloides stercoralis prevalence was dependent on age (P = 0.04). The prevalence in dogs depended on age and breed (χ2 ,P < 0.05) but not on sex (χ2 ,P > 0.05). Hookworms, Taenia spp and Trichuris vulpisoccurred in humans and dogs. Hookworms were the most common helminth of both humans and dogs. Individual factor (coefficient) on the effect of risk factors on specific helminths is essential in understanding the epidemiology of each helminth. Attention should be paid to control measures in man anddogs.
Morbillivirus contains viruses that are highly infectious, spread via the respiratory route, causes profound immune suppression, and have a propensity to cause large outbreaks associated with high mortality in the previously unexposed population. In populations with endemic virus circulation, the epidemiology changes to that of a childhood disease, as they survive the infection normally develop lifelong immunity
This was a prospective cross sectional hospital based study included 117 patients with a definitive history of snake bite and clinical features consistent with the pres¬ence of fang marks at the emergency department, Gadarif Hospital, Eastern Sudan from 1st January 2015 to 1st January 2016 to identify the epidemiological factors of snake bite. The majority of these 117 patients were adult (86.3%) and male gender constituted 85.4%. Most of the patients were of rural residence (65.8%) and were involved in farming related activities (68.3%). A relatively high proportion of snake bite episodes happened in the afternoon times (53.9%) and half of the cases were reported during August (18%) and November. (12.8%). Lower limbs were involved in maximum number of the cases (83.7%). The reported systemic reaction included: swelling (100%), sweating (100%), hypotension (54.7%), nausea (51.%), vomiting (47.8%), local bleeding (13.6%), hymoptysis (1.7%) and neurotoxic symptoms (0.8%). In this study, there were ten (8.5%) deaths; 7 had grade 3 and the other three patients had grade 4 envenomation. In conclusion Snake bites is a real medical threat in Eastern Sudan; thus, it is very important to educate the native people to increase awareness about the risk of snake bites in particular among male, farmers and during the period from August to November.
Similar to AI transmission risks: Analysis of biosecurity measures and contact structure (20)
Low Atmospheric Pressure Stunning is not a humane alternative to Carbon Dioxi...Harm Kiezebrink
I would like express gratitude to the HSA for their 20 years of tireless advocacy for improving pigs' welfare. Their efforts have empowered those seeking alternatives to carbon dioxide stunning. Over nearly 30 years, I've worked on animal welfare friendly stunning applications, particularly regarding stunning/slaughtering using nitrogen foam, and I believe I've found the definitive answer.
The industry originally adopted large-scale carbon dioxide stunning to optimize food production, reduce costs, and lower meat prices, which is only feasible with parallel processing (simultaneously stunning groups of pigs) rather than serial processing (stunning each pig individually). Electrocution is not viable for large-scale operations due to this need for parallel processing. Therefore, a replacement gas that lacks carbon dioxide's detrimental properties is needed, but only a few gases are suitable.
Additionally, the application of an alternative gas must adhere to several fundamental principles:
a) Applicability of the methods for stunning and killing pigs, including their scalability for large-scale application.
b) Description of the technical.
c) Animal welfare consequences associated with specific techniques, including welfare hazards (ABMs), animal-based indicators (ABIs), preventive and corrective measures, and the sufficiency of scientific literature in describing these consequences.
d) Applicability under field conditions.
Introducing a novel application for large-scale pig slaughter is complex and time-consuming before it can be expected, especially given the substantial economic and financial impact for the industry. However, there is hope on the horizon.
The alternative gas is nitrogen, and the application is based on using high-expansion foam filled with 100% nitrogen, applied in a closed container. Within a minute, all air is displaced by the foam, after which the container is sealed, and the foam is broken down with a powerful nitrogen pulse. This ensures that the foam does not affect the stunning process; the entire process can be visually and electronically monitored, and the residual oxygen level in the container is consistently below 2%. The container dimensions are identical to the gondolas used in the globally implemented carbon dioxide gondola system.
The integration of nitrogen foam technology into European regulation EU1099/2009 is nearing completion. All scientific and technical procedures have been submitted to the EU Commission, with finalization awaiting the presentation of EFSA's scientific opinion to the Commission and subsequent approval for inclusion. This final phase is anticipated to occur during the general meeting slated for June 2024.
This marks the first step toward replacing carbon dioxide in 25 years. Fingers crossed for the EU Commission's decision in June 2024!
Harm Kiezebrink
Independent Expert
Preventief ruimen bij vogelgriep in pluimveedichte gebieden en mogelijkheden ...Harm Kiezebrink
New Risk assessment model
The applications designed for farrow-to-weaner pig farms rely on a novel risk assessment model. This model, developed from a recent study, indicates that the likelihood of an undetected infection on nearby farms notably diminishes 7 to 14 days following the identification of the source farm.
This risk assessment model is based a Dutch study that is published by T.J. Hagenaars et al on June 30, 2023: “Preventief ruimen bij vogelgriep in pluimveedichte gebieden en mogelijkheden voor aanvullende bemonstering” (Preventive culling in areas densely populated with poultry, and possibilities for additional sampling).
According to this premise, instead of the standard depopulation approach of euthanizing pigs on-site, pigs beyond the immediate vicinity of infected farms are slaughtered.
Animal Health Canada is currently evaluating new strategies and technologies for managing large-scale emergency situations involving pigs. I have been actively involved in developing strategies and procedures aimed at implementing strict control measures for pig euthanasia during emergencies, with a focus on substantially reducing costs by avoiding unnecessary culling and destruction of healthy animals.
Opting for slaughtering over on-farm euthanasia not only reduces the operational burden on farms but also repurposes the pigs as a valuable protein source rather than considering them as animal waste. This approach assists in crisis management during widespread outbreaks, significantly reduces expenses, and simultaneously mitigates risks.
While this approach is influenced by the new EU regulations implemented since May 2022, it can be adapted for implementation within the context of any EU Member state, as well as in the USA and Canada.
Managing large-scale outbreaks at Farrow-to-Weaner FarmsHarm Kiezebrink
In the face of large-scale outbreaks of swine Influenza A Virus (swIAV), there's a call for exploring various strategies conducive to managing emergencies in field conditions.
Through subdivision, a customized approach can be embraced to enhance operational efficiency and effectiveness while mitigating the impact on individual farms. This tactic maximizes emergency deployment capacity and streamlines standard procedures. Moreover, leveraging the existing capacity of farming aids in alleviating scrutiny on animal welfare standards, presenting a notable advantage.
Nitrogen filled high expansion foam in open ContainersHarm Kiezebrink
On March 31, 2023 the US National Pork Board validated a study by Todd Williams, of Pipestone Veterinary Services, based on the use of high expansion nitrogen foam for the large-scale depopulation of all classes of swine, utilizing Livetec Systems Nitrogen Foam Delivery System (NFDS).
The high expansion foam produced by the Livetec Systems NFDS surrounds the animal in large bubbles filled with nitrogen with a base expansion ration of between 300 and 350 to 1, as mentioned on the information provided by the producer of the firefighting foam.
The Livetec technology, based on using Compressed Air Foam (CAF) filled with nitrogen instead of air for depopulating pigs, emerges within a critical landscape. The complexities of implementing effective emergency depopulation strategies for livestock, particularly swine, present multifaceted challenges. Livetec's approach relies on high expansion firefighting foam, aiming to euthanize pigs by submerging them in foam.
The Livetec system's claims about the effectiveness of nitrogen-filled high expansion foam for depopulating market pigs lack substantial evidence upon analysis. The discrepancy between the actual foam produced during field trials and the promised high expansion foam, coupled with the absence of concrete proof supporting the method's efficacy, discredits the technology's claims.
World bank evaluating the economic consequences of avian influenzaHarm Kiezebrink
Pandemics cause very serious loss of life, restrictions of freedom and serious economic damage. Potential pandemics all are related to our dealing with animals, both wild and domesticated.
In this Word Bank study of 2006, the effects of a severe HPAI pandemic (with a highly pathogenic avian influenza virus crossing the species barrier and infecting humans) predicted economic losses from 2-10% of the world economy.
The economic impact of the present COVID-19 crisis, caused by the SARS-CoV2 virus spreading from wild animals to humans, probably will reach the upper limits of this prediction even if the losses of life might be near the lower limits mentioned in the report (1,4 millions rather than 71 millions).
A common observation is that governments were late to react on the COVID-19 outbreak.
Pandemics are rare, so due to cost-benefit considerations emergency preparations do usually not get beyond an advisory (paperwork) phase. When an emergency eventually arises, the response is too late, too little, and with disastrous effects on animal and/or human welfare that could have been avoided. Relatively small, short-term financial savings result in big, long-term losses.
Protection against outbreaks cannot be achieved by political decisions during a crisis. Our dealing with animals, especially in animal production, must be inherently safe so that animal health and public health are protected.
This is recognized in the One Health strategy that has been adopted internationally.
An outbreak of animal disease occurs should be contained at a very early stage. This can only be realized if all farms have their own emergency plans, with equipment to deal with contagious diseases already present at the farm.
Gas alternatives to carbon dioxide for euthanasia a piglet perspectiveHarm Kiezebrink
The use of nitrous oxide as an anesthetic/euthanasia agent may prove to be affordable, feasible and more humane than other alternatives.
The neonatal stage is a critical time in the life of a pig, when they are prone to become sick or weak. This is the stage at which most euthanasia procedures are required if the pig is judged unable to recover. Any euthanasia method should be humane, practical, economical and socially acceptable to be universally accepted.
They found that nitrous oxide in oxygen appeared to be less aversive than nitrous oxide, nitrogen, or argon all combined with low (30%) concentrations of carbon dioxide or 90% carbon dioxide by itself.
This study is the first to investigate the use of nitrous oxide at sufficiently high concentrations to cause anesthesia. Nitrous oxide, commonly referred to as laughing gas, has been widely used in human surgery and dental offices for its pain-relieving, sedative and anxiolytic effects. It is cheap, non-flammable, non-explosive, legally accessible and not classified as a drug in the U.S., and already commonly used in the food industry as a propellant for food products.
Development of its use into an automated procedure will allow producers to implement it with little effort. Thus its use as an anesthetic/euthanasia agent may prove to be affordable, feasible and more humane than other alternatives.
Anoxia: High expansion foam
The Anoxia method is unique for creating an environment without oxygen under atmospheric circumstances. High expansion foam is produced by mixing nitrogen and a mixture of water and specially developed high expansion detergent, with an expansion rate upto 1:1000, meaning that 1 litre of water/foam agent mix expands up to 1 m3 foam. Due to the specially designed foam generator, the high expansion foam bubbles are filled with a > 99% concentration of nitrogen. The oxygen level surrounding the animal drops from 21% in atmospheric air to < 1 % once the animal is submerged in the foam.
Anoxia: convulsions, but no stress or pain
The animals need a constant supply of oxygen to the brain. Applying Anoxia foam, the oxygen is replaced by nitrogen. As a result the nitrogen level is raised to > 99% and the oxygen level is lowered to < 1%. Considering the natural reaction to sudden lack of oxygen the animal is rendering quickly into unconsciousness. As a consequence, behavioral indicators like loss of posture and convulsions will appear. With this in mind, unconscious animals are insensitive to perceive unpleasant sensations like pain.
Anoxia: How Anoxia foam is created
A mixture of 97% water and 3% high expansion foam agent is sprayed into the Anoxia foam generator, creating a thin film on the outlet of the generator. At the same time, nitrogen is added with overpressure into the foam generator. The nitrogen expands when it exits the generator, creating robust high expansion foam. The high expansion foam bubbles are filled with > 99% nitrogen.
Anoxia: Single foam generator systems
In practice, one Anoxia foam generator creates a volume of up to 750 liter of high expansion foam per minute. This volume is more than sufficient to fill a wheelie-bin container within 30 seconds. The most common container volumes are: M size - 240 liter; L size - 340 liter; and XL size - 370 liter. The choice of the volume of the container depends of the size of the animal and/or the number of animals that need to be stunned/killed. A lid with a chiffon that seals the container. As soon as the foam exits the chiffon, the gas supply is stopped and the chiffon is closed. The nitrogen gas concentration in the container remains at 99%.
Although commonly used in other settings, defining animal welfare as part of a corporate CSR setting is not new.
There are many ways to define CSR. What they have in common is that CSR describes how companies manage their business processes to produce an overall positive impact on society. The phenomenon CSR is a value concept that is susceptible to particular ideological and emotional interpretations. Different organizations have framed different definitions - although there is considerable common ground between them.
Some important national players of the food chain at different steps (mainly food retailers and food services) have included animal welfare in their CSR.
The Anoxia technique is developed as alternative for existing animal stunning methods that are based on the use of CO2, electrocution, neck dislocation, captive-bolt, as well as killing methods like de-bleeding and maceration.
In the past 10 years, Wageningen University and University of Glasgow conducted several studies that proved that the technique could be applied successfully for culling poultry (Proof of Principle Anoxia Technique). This was the start of the development of several applications based on the Anoxia principle, using high expansion foam filled with >99% Nitrogen that are now introduced for:
1. Stunning and killing of sick and cripple killing piglets less than 5 kg
2. Stunning and killing of sick or cripple poultry (especially poultry > 3kg) who need to be killed on the farm by the staff for welfare purposes (avoiding unnecessary stress or pain)
3. Stunning and killing poultry that arrives on the slaughterhouse but that are unfit to be slaughtered (due to injuries occurred during transportation – providing signs of possible illness etc.)
4. Stunning and killing of male pullets at the hatchery
5. Stunning and killing of half-hatched chickens and embryos in partly-hatched eggs, before destruction
6. Stunning and killing parent stock poultry
7. Killing of animals that has been stunned (captive bolt – blow-on-the-head method, etc.) replacing killing by de-bleeding
8. Culling of ex-layers
9. Culling of poultry for disease control purposes
Last November we started the launch of the commercialization of the Anoxia applications in Holland, Germany and Sweden, focusing on the areas where a solution is most needed: piglets (< 5kg) and poultry (> 3kg) on farms.
Since November 2016, the introduction of these applications took place in Holland, Germany, Sweden and Denmark
World Health Organization director- general Margaret Chan Fung Fu-chun warns bird flu H7N9 is particularly worrying as it could be a flu pandemic strain. This is because H7N9 is unique as it does not make chickens sick but is deadly in humans. Sick birds could usually provide early warning for imminent outbreaks, Chan told The Standard. This comes as Macau reported its first human case of H7N9 yesterday. "The biggest challenge for the world is the next influenza pandemic," Chan said.
Laves presentation practical experiences in the culling of poultry in germanyHarm Kiezebrink
This presentation, based on the practical experiences in culling poultry in Germany, gives an overview of the culling techniques currently in use in Germany. It is presented by dr. Ursula Gerdes, dr. Josef Diekmann and ing. Rainer Thomes.
LAVES is the Lower Saxony State Office for Consumer Protection and Food Safety, located in Oldenburg, Germany. With around 900 employees they are entrusted with tasks in the areas of food and utensil inspection, feed inspection, meat hygiene, veterinary drug monitoring, eradication of animal diseases, disposal of animal by-products, animal welfare, ecological farming, market surveillance and technical process monitoring.
Berg et al. 2014 killing of spent laying hens using co2 in poultry barnsHarm Kiezebrink
September 2015: In Sweden, spent laying hens are killed either by traditional slaughter; on-farm with CO2 in a mobile container combined with a grinder; or with CO2 stable gassing inside the barn. The number of hens killed using the latter method has increased. During these killings a veterinarian is required to be present and report to the Swedish Board of Agriculture.
Data were registered during four commercial killings and extracted from all official veterinary reports at CO2 whole-house killings in 2008–2010. On-farm monitoring showed that temperature decreased greatly and with high variability. The time until birds became unconscious after coming into contact with the gas, based on time until loss of balance, was 3–5 min.
Veterinary reports show that 1.5 million laying hens were killed, in 150 separate instances. The most common non-compliance with legislation was failure to notify the regional animal welfare authorities prior to the killings. Six out of 150 killings were defined as animal welfare failures, eg delivery of insufficient CO2 or failure to seal buildings to achieve adequate gas concentration.
Eleven were either potentially or completely unacceptable from the perspective of animal welfare. We conclude that, on the whole, the CO2 whole-house gas killing of spent hens was carried out in accordance with the appropriate legislation. Death was achieved reliably.
However, there remain several risks to animal welfare and increased knowledge would appear vital in order to limit mistakes related to miscalculations of house volume, improper sealing or premature ventilation turn-off.
The latest outbreak of High Pathogen Avian Influenza in the USA and Canada in the spring of this year and the inability to avoid animal welfare catastrophes ultimately proves that new emergency response strategies are needed. Strategies that are based on taking away the source of infection instead of killing as many animals as possible within 24 hours, regardless the consequences.
The statement that “It’s possible that human infections with these viruses may occur” and that “these viruses have not spread easily to other people” is confusing. Humans can become infected without showing clinical signs. They can become the major carrier of the infection.
Especially during depopulation activities, viruses easily transmit through responders. Tasks like taking layers out of their cages and transport the birds manually through the narrow walkways between the cages, and disposal of infected animals are specific risks that need to be avoided. Simply switching of the electricity so that sick birds don’t have to be handled is not the solution.
Although humans are supposed to be less susceptible, they can become carrier of the virus. Only the highest level of biosecurity could prevent the transmission through the humans and materials that have been in direct contact with infected animals and materials.
Simply switching of the electricity so that sick birds don’t have to be handled is not the solution. Avoid killing animals is always the better option and in Germany, the discussion on the strategy based on neutralizing risks and is in the making. Avoiding situations demands a proactive role of the poultry industry.
Ventilation Shutdown: who takes the responsibility to flip the switch?Harm Kiezebrink
On September 18, 2015 the USA Government and the American egg producers announced that they would accept the Ventilation shutdown method as a method of mass destruction of poultry when other options, notably water-based foam and CO2, are not available for culling at the farm within 24-36 hours. This is actually the case on all caged layer farms in the USA, in particular in Iowa.
The Ventilation shutdown method consists of stopping ventilation, cutting off drinking water supply, and turning on heaters to raise the temperature in the poultry house to a level between 38 Celsius and 50 Celsius. Birds die of heat stress and by lack of oxygen in a process that easily takes over after a period of at least 3 days. Ventilation shutdown is a killing method without prior stunning of the birds, and as such is contrary to all international Animal Welfare standards.
Animal welfare specialists in disease control strongly oppose this introduction of the cruelest method of killing poultry that lost their economic value. The Humane Society (HSUS) described it as the “inhumane mass baking of live chickens”. With adequate preparation the alternative methods, like the water-based Anoxia foam method, can be available at each farm for immediate use in case of an outbreak. The ban of the Ventilation shutdown method should therefore be maintained and the Anoxia method should be further developed so that is suitable for application to caged layers and turkeys. In Germany, such a system is currently under development and will become commercially available soon.
The poultry industry in the USA ignores this development and asks for a formal approval of the Ventilation Shutdown method. Speaking on August 19, 2015, during the United Egg Producers (UEP) national briefing webinar, UEP President Chad Gregory explained that much research is being done concerning the feasibility of such a depopulation program.
“The government, the producers, the states and UEP, we all recognize that depopulation is going to have to happen faster and ideally within 24 hours.”
Quick depopulation of affected flocks is important, Gregory said, because the sooner a flock is depopulated, the risk of the virus going into fans and out into the atmosphere becomes smaller. Gregory said ventilation shutdown – if approved – would probably only be used in a worst-case scenario or when all other euthanasia options have been exhausted. Gregory did not elaborate on how to adequately prevent outbreaks and how to promote more animal-friendly methods.
In order to become one step ahead of an outbreak of high pathogen diseases like the current H5N2, the veterinary authorities need to stop the outbreak immediately after the first signals occur. Strict and thorough biosecurity measures are the most fundamental feature to protect poultry flocks on farms.
Without functional culling techniques, the options to effectively and efficiently cull in average more than 925,000 chickens per farm (in Iowa, USA) are limited: either by macerating the chickens alive – or by ventilation shut-down (closing down all ventilation, placing heaters inside the house, and heat the entire house to a temperature higher than 600 C).
Although both methods cause death of the birds, it has not been proven to be effective nor efficient. The primary goal to slowdown outbreaks and bring it to a complete stop but macerating live birds and killing them by heat stress and lack of oxygen would be against all International Animal Welfare standards.
Animal welfare specialists in disease control strongly oppose against the introduction of these most cruel methods of killing poultry and argue that the ban on these methods should be maintained and alternative methods need to be considered.
Avian Influenza in the Netherlands 2003: comparing culling methodsHarm Kiezebrink
During the outbreak of H7N7 in Holland, 29,500.000 birds were killed at the farm. This presentation compares different culling techniques, such as stable gas, container gassing and electrocution.
Reseach on H9N2: evidence that link outbreaks in Eurasia, China, South Korea,...Harm Kiezebrink
In this study, scientists from the U.S. Geological Survey and U.S. Fish and Wildlife Service harnessed a new type of DNA technology to investigate avian influenza viruses in Alaska. Using a “next generation” sequencing approach, which identifies gene sequences of interest more rapidly and more completely than by traditional techniques, scientists identified low pathogenic avian influenza viruses in Alaska that are nearly identical to viruses found in China and South Korea.
The viruses were found in an area of western Alaska that is known to be a hot spot for both American and Eurasian forms of avian influenza.
“Our past research in western Alaska has shown that 70 percent of avian influenza viruses isolated in this area were found to contain genetic material from Eurasia, providing evidence for high levels of intercontinental viral exchange,” said Andy Ramey, a scientist with the USGS Alaska Science Center and lead author of the study. “This is because Asian and North American migratory flyways overlap in western Alaska.”
The new study, led by the USGS, found low pathogenic H9N2 viruses in an Emperor Goose and a Northern Pintail. Both of the H9N2 viruses were nearly identical genetically to viruses found in wild bird samples from Lake Dongting, China and Cheon-su Bay, South Korea.
“These H9N2 viruses are low pathogenic and not known to infect humans, but similar viruses have been implicated in disease outbreaks in domestic poultry in Asia,” said Ramey.
There is no commercial poultry production in western Alaska and highly similar H9N2 virus strains have not been reported in poultry in East Asia or North America, so it is unlikely that agricultural imports influenced this result.
The finding provides evidence for intercontinental movement of intact avian influenza viruses by migratory birds. The USGS recently released a publication about the detection of a novel highly pathogenic H5N8 virus in the U.S. that is highly similar to the Eurasian H5N8 viruses. This suggests that the novel re-assortment may be adapted to certain waterfowl species, enabling it to survive long migrations. That virus, and associated strains, have now spread from early detections in wild and domestic birds in Pacific states to poultry outbreaks in Minnesota, Missouri and Arkansas.
“The frequency of inter-hemispheric dispersal events of avian influenza viruses by migratory birds may be higher than previously recognized,” said Ramey.
While some of the samples for the project came from bird fecal samples collected from beaches at Izembek National Wildlife Refuge, most of the samples came from sport hunters.
“For the past several years, we’ve worked closely with sport hunters in the fall to obtain swab samples from birds and that has really informed our understanding of wildlife disease in this area,” said Bruce Casler, formerly a biologist with the USFWS Izembek National Wildlife Refuge and a co-author of the study. Non
Risk analysis on the role of wild ducks by the introduction of Avian Influenz...Harm Kiezebrink
Lelystad, April 2015: According to a recently published study (in Dutch) by the University of Wageningen, wild ducks are are identified as a high risk factor for the introduction of Low Pathogen Avian Influenza viruses in free-range laying hens.
Through a case-control study investigated presumed risk factors for introduction of low-pathogenic avian influenza (LPAI) virus in poultry laying farms free range. Under a LPAI virus was defined in this study: an avian influenza virus of each subtype (H1 H16 tm), with the exception of the highly pathogenic avian influenza (HPAI) viruses.
In order to determin the potential risk factors for infection with LPAI virus, forty Dutch free range poultry farms where the introduction of Low Pathogen Avian Ifluenza virus has been confirmed in the past (cases) were compared with 81 free range poultry farms where no introduction has taken place (controls). Questions about the presence of potential risk factors through surveys submitted to the poultry farmers.
The analysis of the various factors shows that the risk of introduction of LPAI virus on free range laying farms 3.3 (95% CI: 1.2-9.7) times higher as mallards has identified by the farmer entering the free range area at least once a week, in comparison to free-range laying farms where wild ducks have been identified by the farmer once a month or less.
It seems logical that the regular presence of wild ducks in the free-range increases the risk exposure of the chickens LPAI virus since wild waterfowl are the natural reservoir of avian influenza viruses.
The study also revealed that the risk factor for free range layer farms located on clay is 5.8 (95% CI: 2.2-15.1) times have higher risk of introduction of LPAI virus then free range layer farms on sandy soil or a soil other than clay. The soil on which the free range farm is situated is probably an indirect risk factor (association and not causation): especially in case the farm is located near the coast or close to rivers.
Anoxia presentation during the AI symposium in Taiwan, March 2015Harm Kiezebrink
During the Symposium on managing outbreaks of Avian Influenza in Taiwan, the main subject was managing the outbreaks without breaching animal welfare during the culling operations. Although it seams impossible, this can be done using the Anoxia method (see also www.N2GF.com for more information), under the condition that the entire process is been taking into account: killing of animals, carcass disposal, transport & logistic, Occupational Health & Safety, environmental issues, pest control, contact between animals and humans: all these factors contribute to the risks of spreading. If one factor fails, the virus can escape and infect the next flock, making it needed to kill more birds. For that reason, all factors are equally important to maintain animal welfare during outbreak situations.
In a number of recently published studies, Professor Stegeman (University of Utrecht, Holland) explains that serologic spreading of viruses is related to human contacts with contaminated infected animals, carcasses, manure and materials infected/suspected animals; movements of farm labourers, products, equipment etc. Most of these contacts (and movements) take place prior, during, and after the culling procedure, whereas the quantity and the intensity of the contacts - thus this human contact/materials are decisive factors for the serologic spreading of viruses to enter farms and most likely play an important role in spreading between farms. Suspicion/infection of farm animals inevitably leads to preventive culling of all farm animals within the direct proximity. For that reason, the serologic spread of viruses has become a major animal welfare indicator that has to be taken into consideration as such.
Each culling procedure features its own unique contact pattern between animals and humans and is based on applied culling, disposal and transport technique. These contact patterns related to the specific combination of applied methods, defines the major contribution factors for spreading of infections. Therefore should the potential risks of these procedures be evaluated and rated on the art and the intensity of the potential contact between animals and humans/materials, prior, during and after the procedure.
Therefore, the entire procedure of killing, disposal and transportation is therefore considered as Major Interest, in terms of animal welfare.
Overview of recent outbreaks of H5N8-High Pathogen Avian Influenza in Europe...Harm Kiezebrink
Updated outbreak assessment on Highly Pathogenic Avian Influenza: Europe, America and the Middle East. By the DEFRA, Veterinary & Science Policy Advice Team - International Disease Monitoring.
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हम आग्रह करते हैं कि जो भी सत्ता में आए, वह संविधान का पालन करे, उसकी रक्षा करे और उसे बनाए रखे।" प्रस्ताव में कुल तीन प्रमुख हस्तक्षेप और उनके तंत्र भी प्रस्तुत किए गए। पहला हस्तक्षेप स्वतंत्र मीडिया को प्रोत्साहित करके, वास्तविकता पर आधारित काउंटर नैरेटिव का निर्माण करके और सत्तारूढ़ सरकार द्वारा नियोजित मनोवैज्ञानिक हेरफेर की रणनीति का मुकाबला करके लोगों द्वारा निर्धारित कथा को बनाए रखना और उस पर कार्यकरना था।
In a May 9, 2024 paper, Juri Opitz from the University of Zurich, along with Shira Wein and Nathan Schneider form Georgetown University, discussed the importance of linguistic expertise in natural language processing (NLP) in an era dominated by large language models (LLMs).
The authors explained that while machine translation (MT) previously relied heavily on linguists, the landscape has shifted. “Linguistics is no longer front and center in the way we build NLP systems,” they said. With the emergence of LLMs, which can generate fluent text without the need for specialized modules to handle grammar or semantic coherence, the need for linguistic expertise in NLP is being questioned.
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‘वोटर्स विल मस्ट प्रीवेल’ (मतदाताओं को जीतना होगा) अभियान द्वारा जारी हेल्पलाइन नंबर, 4 जून को सुबह 7 बजे से दोपहर 12 बजे तक मतगणना प्रक्रिया में कहीं भी किसी भी तरह के उल्लंघन की रिपोर्ट करने के लिए खुला रहेगा।
role of women and girls in various terror groupssadiakorobi2
Women have three distinct types of involvement: direct involvement in terrorist acts; enabling of others to commit such acts; and facilitating the disengagement of others from violent or extremist groups.
2. A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115 107
1. Introduction
The poultry industry makes a significant contribution
to the Dutch national economy. For example, in 2011, the
average broiler population was more than 45 million birds,
the laying hen population was close to 33 million birds and
close to 900,000 tonnes of poultry meat and close to 10
billion eggs and egg products were exported (PVE, 2012).
The profitability of this industry was severely affected by
the occurrence in 2003 of an H7N7 highly pathogenic avian
influenza (HPAI) virus epidemic. In addition, this epidemic
presented a risk to human health, both through trans-
mission of the circulating virus to humans and through
its assumed potential to seed the development of a new
pandemic influenza strain (Koopmans et al., 2004). The epi-
demic comprised 255 outbreak farms, 30 million birds were
culled (Stegeman et al., 2004) and 89 people were infected,
one of whom died (Koopmans et al., 2004). The direct costs
as a result of bird deaths and depopulation amounted to
D250 million, while indirect costs due to the epidemic were
much higher (Tacken et al., 2003; Meuwissen et al., 2006).
Although, after diagnosis of the first cases of the epi-
demic, movement bans and other control measures were
put in place, a continued spread of the virus was observed.
In spite of the culling of contiguous flocks, i.e., flocks that
were in the neighbourhood of the outbreaks or that had
had contact with an infected farm, this spread continued
for weeks in particular in the high poultry density areas
(Stegeman et al., 2004). The transmission pattern during
the epidemic indicates the presence of (untraced) indirect
transmission routes or mechanisms that are not controlled
by the European Commission’s strategies. Hence in order to
possibly improve control strategies, a better understanding
of indirect transmission mechanisms is needed.
AI viruses may be introduced into poultry from reser-
voirs such as aquatic wild birds (Webster et al., 1992;
Alexander, 2000, 2007; de Jong et al., 2009) but the mech-
anisms of their subsequent spread are partially unclear.
Transmission of the virus through movements of humans
(visitors, servicemen and farm personnel), vectors (wild
birds, rodents, insects), air- (and dust-) related routes and
other fomites (e.g., delivery trucks, visitors’ clothes and
farm equipment) have all been hypothesized (Halvorson
et al., 1980; Webster et al., 1992; Sawabe et al., 2006;
Sievert et al., 2006; Ssematimba et al., 2012a,b).
It is therefore hypothesized that the risk of introducing
the virus to a farm is determined by the farm’s neighbour-
hood characteristics, contact structure and its biosecurity
practices. On the one hand, neighbourhood characteris-
tics include factors such as the presence of water bodies
(accessed by wild birds), the density of poultry farms
(together with the number and type of birds on these farms)
and poultry-related businesses and the road network. The
use of manure in the farm’s vicinity is also deemed to be
risky (Alexander, 2000, 2007; Swayne and Suarez, 2000;
Thomas et al., 2005). On the other hand, contact struc-
ture risk factors include the nature and frequency of farm
visits. Therefore, a detailed analysis of the contact structure,
including neighbourhood risks, and biosecurity practices
across different types of poultry farms and poultry-related
businesses could help the improvement of intervention
strategies, biosecurity protocols and adherence to these,
as well as contact tracing protocols. Farmers’ perception of
visitor- and neighbourhood-associated risks of virus spread
is also important due to its relevance to adherence with
biosecurity protocols, to contact tracing and to communi-
cating advice to them.
The between-farm virus transmission risks may be
split into two categories namely, introduction and
onward-spread risks. The former entail the target farm’s
exposure through incoming contacts (human and fomite),
through inputs such as feed and egg trays and through
neighbourhood-related risks such as air-borne contami-
nation. The latter can be through farm outputs (waste
and non-waste), outgoing contacts (human and fomite)
and contamination of the neighbourhood (e.g., through
emissions from the farm). Therefore, we systematically
analysed all day-to-day farm activities involving people
and/or materials and/or equipment going in or out of the
farm.
Through questionnaire-guided in-depth interviews, we
sought information directly from the farmers and the
poultry-related businesses. These interviews were aimed
at gathering first-hand information about all the visits
and processes involved and the accompanying biosecurity
practices throughout the production round and across all
poultry husbandry types. Other aspects of interest were
the details about the farm’s neighbourhood which are
important in relation to indirect transmission risks. In the
interviews, we aimed to learn more about possible risks in
practice corresponding to the indirect contact types that
are commonly hypothesized and/or that can be found in
the tracing reports of the H7N7 epidemic in 2003 and any
further possible indirect contact types, in particular those
that could provide a pathway for the untraced outbreaks
(or ‘neighbourhood infections’).
Based on the gathered information, we generated a list
of contact types that could serve as avian influenza (AI)
transmission pathways. For these contact types, we then
performed a qualitative risk assessment based on contact
type, their corresponding biosecurity practices and con-
tact frequency to ascertain which mechanisms are the most
important to target during prevention and control.
2. Materials and methods
2.1. Study population
A cross-sectional study was performed with the aim of
obtaining information on the types and frequency of the
various day-to-day farm contacts and activities that can
guide the determination of potential pathways of AI spread
between poultry farms. The study involved 42 farmers and
18 poultry-related business representatives distributed all
over The Netherlands. The stratum-specific sample sizes
for the farms/firms to be interviewed were determined
based on the underlying goal of making sure that all rele-
vant types in the poultry chains were included. By sampling
more farms from those strata representing a higher popula-
tion proportion an attempt was being made to capture any
between-farm variation in biosecurity practices present.
3. 108 A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115
In 2009, there were approximately 687 broiler, 1097
layer, 248 breeder, 54 turkey and 66 duck farms and the
layer farms comprised of approximately 10% organic, 17%
free range, 53% deep litter and 20% cage farms (PVE, 2012).
From the national list available in the poultry produc-
tion chain information (KIP) database, a random selection
of 13 layer, nine broiler, four turkey, two duck, four
broiler-breeder, eight pullet, one vaccine-egg producing
and one organic/biological layer was made. For the poultry-
related businesses, four hatcheries, two slaughterhouses,
two egg grading companies, two feed mills, two manure
plants/traders, two catching companies, two repair com-
panies and two poultry veterinarians were included in the
study.
2.2. Questionnaire design and data collection
Two questionnaires (one posed to the poultry farm-
ers and the other to representatives of poultry-related
businesses, both available upon request) were developed
together with two (retired) experts who had worked in
the Dutch poultry industry. They contained 125 and 296
closed, semi-closed and open type questions for the first
and second round of interviews respectively. Participation
in the survey was voluntary and for those that agreed to
take part, appointments for the interviews to be held on
the firm premises were made. All the selected farms and
poultry-related businesses were visited and personal inter-
views conducted (in Dutch) between May and December
2009. In the first round of interviews, the questionnaire for
the poultry farms was pre-tested on two farms, adjusted,
and administered to the 42 farms. In the second round,
the second questionnaire specifically designed for poultry-
related businesses was administered to the 18 company
representatives and professionals.
In addition to this data, we also needed a detailed list of
locations of the various poultry-related businesses in The
Netherlands for the assessment of the interviewed farms’
neighbourhoods. Such a list could not be obtained from
a single source; we generated it by extracting company
information using ‘Google’ and combining the results with
information available on a Dutch website, the ‘Pluimvee
Gids’ (Poultry Directory). Numbers of farms in the neigh-
bourhoods were obtained from poultry farm location data.
2.3. Data management and descriptive analysis
Data gathered from the interviews were entered into
a database file. Both data (from the interviews and the
‘Google’ extracted) were descriptively analysed to check
the presence or absence of and/or determine the frequency
of occurrence of events and practices that can promote
virus transmission. In order to eliminate biased conclu-
sions resulting from inaccurate reporting, farmer responses
were compared with those of the poultry-related business
representatives or were cross-checked with the poultry
production chain information (KIP) database, maintained
by the Product board for Poultry and Eggs (PPE), which
contains the location of all commercial poultry farms in The
Netherlands. Estimates of the number of farms and poultry-
related businesses within a 5 km radius around each of the
interviewed farms as provided by the farmer were com-
pared to actual numbers obtained using farm location data
and Geographic Information System (GIS). These findings
were necessary for assessing neighbourhood-related con-
tamination risks whereby we used the extracted numbers
to infer qualitatively about the risk of farm contamination.
It is also important in assessing the farmers’ knowledge
of their neighbourhood in terms of poultry density and its
potentially associated risks.
2.4. Categorizing contacts and generating transmission
pathways
The outcomes of the descriptive analysis were used
to inform the generation of transmission pathways. We
hypothesized potential pathways of virus transmission
comprising of one or combinations of several of the
reported activities. A pathway is here defined as a combi-
nation of activities and behaviours that can promote virus
dissemination. Examples of pathways are: a person moving
between farms without adhering to the farms’ biosecu-
rity protocols or a scenario in which poultry manure is
used in the neighbourhood of a non-protected poultry
farm.
We grouped the pathways into the following five
categories: (1) between-farm movement of poultry, (2)
between-farm movement of persons and equipment that
access poultry houses, (3) between-farm movement of
persons and equipment that access storage rooms only,
(4) between-farm movement of persons and equipment
that were only on the premises and, (5) neighbourhood-
related contamination risks. The distinction of the four
different between-farm movement categories was based
on decreasing proximity of approach to the poultry
by the persons or equipment when on the farm.
Table 1
Proposed exposure risk classification scheme based on contact frequency, biosecurity practices and risk category.
Average number of contacts per year
≥10 <10 and ≥3 <3 and ≥1 <1 and >0 ≈0
Category I: movement of poultry between farms n.o.b
Very high n.o.b
Medium Negligible
Category II: contacts accessing poultry houses Very high Very high High Medium Negligible
Category III: contacts accessing storage rooms Very high High Medium Low Negligible
Category IV: premises-only contacts Very high High Medium Low n.o.b
Category V: neighbourhood risksa
Very high n.o.b
Medium n.o.b
n.o.b
a
no contacts per year estimated, the risk is derived based on the number of farms or poultry-related businesses in the 5 km × 5 km neighbourhood.
b
n.o. stands for ‘not observed’.
4. A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115 109
2.5. Qualitative risk assessment
This analysis used a risk ranking scheme based on the
five pathways (Section 2.4) and the annual frequencies of
contacts. Here (in contrast to other analyses), we concen-
trated on the end-of-chain broiler (hereafter referred to as
broiler) and layer husbandry types since these two together
present the majority of farms in the Dutch poultry indus-
try. Our risk ranking scheme (Table 1) ranks the identified
contacts in terms of the overall risk they pose, based on
the combination of the per-contact risk and the annual
contact frequency. The highest per-contact risk level was
assigned to category I pathways with the other categories
being assigned systematically decreasing levels, based on
decreasing proximity of approach to the poultry by the
persons or equipment when on the farm. The frequency-
related risk levels were assigned on an interval basis with
more than ten contacts per year having the highest risk and
the lowest risk interval being that of no contacts at all. The
framework was applied to all the different contact types
identified in layer and broiler farms to rank these contact
types according to the risks posed, with the risk level in
principle being dependent on the husbandry type.
3. Results
3.1. General interview findings
Only about 10% of the contacted farmers and firm repre-
sentatives declined to take part and were replaced by other
farmers or firm representatives within the same stratum.
Both the study population and the geographical cover-
age of the selected enterprises were representative of the
majority of the poultry husbandry types and the regions in
The Netherlands. From the farm neighbourhood analysis,
most farmers somewhat underestimated numbers of poul-
try farms present within a 5 km radius around their farm.
The average percentage by which their estimate under-
scored the GIS-extracted number was 51%.
Hired labourers are known to play a big role in inter-
connecting farms. Here we found that 32 farms hired
external labour of which seven accessed other poultry on
the same day. However, they were not the only ‘connec-
tors’ as some (twelve) farmers also reported themselves
helping on other poultry farms. Furthermore, 27 farms had
family members visiting poultry or poultry-related busi-
nesses of which nine entered poultry houses during those
visits. The other enhancing factor of farm interconnections
was the reported ownership of multiple locations for ten
of the interviewed farms and the reported on-premises
sale of farm products on one pullet and eight layer farms.
Also worth mentioning is the practice of a multiple age
system reported on eight of the interviewed farms as this
may increase the risk of infecting remaining birds when
off-premises poultry movements occur.
On 32 of the interviewed farms, the presence of
other animal (non-poultry) species on the premises was
reported. Manure use on agricultural fields in the neigh-
bourhood of the farm was reported on ten of the
interviewed farms. In terms of risk perception in rela-
tion to AI introduction, only 17 of the interviewed farmers
Table2
Summaryofselectedgeneralinformationobtainedfromthequestionnairesurvey.
LayerBroilerDuckTurkeyPulletBroilerbreederOrganic
Averagenumberofbirdsoneachfarm
(min,max)
41,975(3350,130,000)52,791(180,160,000)27,500(15,000,40,000)14,724(9000,19,000)62,844(10,000,252,900)16,250(6000,28,000)12,000(n=1)
Numberoffarmswith>1locations5103100
Numberoffarmswithoutdoorrun4000101
Numberoffarmswithmultipleage
system
4013000
Numberoffarmswherethefarmer
visitsotherpoultryfarms
7301010
Numberoffarmswherefamily
membershaveaccesstoother
poultry
11313621
Averagenumberoffarmsin
5km×5km:reported(extracted
usingGIS)
11(37)6(20)41(113)39(64)7(30)18(19)22(33)
Numberoffarmswherethefarmer
perceivestherisk(inrelationtoAI
introduction)posedbywaterbodies
inthefarmneighbourhoodashigh
5511230
5. 110 A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115
Fig. 1. Number of farmers with a similar perception of the risk of Avian Influenza virus transmission associated with individual farm visitors.
perceived the presence of water bodies in their neighbour-
hood as posing a high risk and the farmers had divergent
opinions about visitor-related risks (Fig. 1). Farm visits
were frequent – for example, feed mill technicians and
veterinarians each accessed poultry houses and storage
rooms on broiler farms for an average of 24.1 and 27 times
per year respectively. More general results are presented
in Table 2.
3.2. Category I pathways: movements of poultry between
farms
The already known movements in this category are dur-
ing restocking and spiking (i.e., adding males in a flock)
a destination farm. We also found that, on some of the
farms, thinning by moving birds to other farms, to slaugh-
terhouses, and to other poultry houses (on the same farm)
are practiced. Thus this is an additional scenario of birds
being moved from one farm to another.
The scenario of movement of infected day-old chicks
means that these chicks are infected either at the hatch-
ery or during transport. The risks for hatcheries to become
contaminated with the virus are associated with a num-
ber of practices reported. These include the inconsistently
applied biosecurity and/or the non-existent biosecurity
facilities at some of the hatcheries as well as their non-
adherence to farm biosecurity protocols.
Bringing personal items into hatchery production
rooms may also be risky, as is the reported interchange
of chick and hatch-egg delivery trucks coupled with the
reported non-thorough cleaning and disinfection between
trips. Re-use of setter trays on three of the interviewed
hatcheries poses a threat of infection propagation inside
the hatchery in case of non-thorough cleaning and disinfec-
tion. Also, between-hatchery business connections may be
important determinants of the contamination risk. These
connections occur through the sale of hatching eggs and
chicks, and the associated contamination risk may also be
enhanced by the reported sourcing of eggs from mixed
sources.
3.3. Category II pathways: movements of persons and/or
equipment between farms that access poultry houses
The already known (and confirmed by this study) con-
tacts accessing poultry houses include professionals (and
professional equipment, for example bird-catching and
vaccination equipment) and non-professional visits (and
equipment) by farm staff (temporal and permanent) or
non-staff visitors. Some farmers themselves, their fam-
ily members and the hired personnel accessed poultry on
other farms and, on pullet farms, future flock-owner (pur-
chaser) visits were also mentioned.
Among the reported, we identified biosecurity prac-
tices that contribute to these risks. These include the
non-adherence to protocols and absence of farm biose-
curity facilities and incomplete protocols (Table 3). There
was inconsistent adherence to farm biosecurity protocols
during restocking with six of the interviewed farms men-
tioning violations. In addition, most farms had showers that
were never used and visitors did not always go through
biosecurity transit rooms. Also, most of the interviewed
farms lacked designated clean/dirty routes and only one
interviewed farm had a marked walking route. Further-
more, all farms allowed personal belongings such as cell
phones and jewellery into poultry houses and some farms
shared equipment that was not always cleaned.
Violation of on-farm biosecurity protocols by the
poultry-related company personnel renders their visits
risky. There are several other visitor-type specific risky fac-
tors. These include veterinarians visiting up to 100 farms of
different types per year and owning all the equipment they
use. As reported, this equipment is not always thoroughly
cleaned and disinfected. For their repairmen, visiting
6. A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115 111
Table 3
Summary on selected farm biosecurity measures and visitor adherence to the available protocols for the different husbandry types.
Layers Broilers Duck Turkey Pullet Broiler breeder Organic
Number of farms (divided by total number reporting a particular visit) on which they do not use biosecurity transit rooms
Veterinarians 0/11 0/9 2/2 0/4 0/8 1/3 0/1
Feed mill technicians 1/12 1/8 2/2 0/2 0/2 1/2 0/1
Hatchery technicians 1/11 0/4 1/1 0/1 1/7 1/1 0/1
Repair technicians 1/10 0/5 2/2 0/4 0/3 0/3 0/1
Inspectors 3/13 3/9 2/2 0/4 4/8 3/3 0/1
Catchers 2/13 1/9 1/1 0/4 2/8 1/3 0/1
Vermin control 1/5 0/1 n.o.a
n.o.a
1/3 n.o.a
0/1
Number of farms (divided by total number reporting a particular visit) on which they deviate from protocols
Veterinarians 1/11 0/9 0/2 0/4 0/8 0/3 1/1
Feed mill technicians 1/12 0/8 0/2 0/2 0/2 0/2 1/1
Hatchery technicians 0/11 0/4 0/1 0/1 0/7 0/1 0/1
Repair technicians 3/10 0/5 0/2 0/4 1/3 1/3 0/1
Inspectors 2/13 0/9 0/2 0/4 0/8 0/3 1/1
Catchers 2/13 0/9 0/1 0/4 0/8 2/3 1/1
Vermin control 0/5 0/1 n.o.a
n.o.a
0/3 n.o.a
0/1
Number of farms (divided by total number reporting a particular visit) on which they enter poultry houses with personal items
Veterinarians 10/11 6/9 0/2 4/4 5/8 2/3 1/1
Feed mill technicians 10/12 5/8 0/2 2/2 2/2 0/2 1/1
Hatchery technicians 9/11 1/4 0/1 1/1 4/7 0/1 1/1
Repair technicians 10/10 3/5 0/2 3/4 2/3 3/3 1/1
Inspectors 4/13 1/9 0/2 1/4 1/8 0/3 1/1
Catchers 12/13 5/9 0/1 3/4 5/8 3/3 1/1
Vermin control 4/5 1/1 n.o.* n.o.* 1/3 n.o.* 1/1
Number of farms with/where
Designated clean and dirty routes 1 0 0 1 1 0 0
Hygiene protocols are violated during restocking 2 1 1 0 0 0 1
Manure container and/or truck not always cleaned 2 3 0 0 3 1 0
Measures to prevent contamination by manure 1 1 1 0 1 0 0
a
n.o. stands for ‘not observed’.
families with poultry on non-official duties and working on
farms with all types of poultry may increase their chances
of contaminating the farms they visit.
The catching companies catch on all types of farms
including day-old chicks at the hatcheries and hence pose a
risk to the farms they visit. The crews of both catching com-
panies used their own clothing and boots and the crew from
one of them took catching cages, compressor, fork truck and
dust covers on their work visits. Catching company repre-
sentatives concurred with the farmers on the poor hygiene
level of these items; both catching companies mentioned
the visually unclean bird crates that they used on different
farms.
3.4. Category III pathways: movements of persons and/or
equipment between farms that only access storage rooms
The already known human and fomite contacts (and
confirmed by this study) include feed mill and egg company
staff contacts as well as repairmen and the equipment they
use. Also, the between-farm use of trays, pallets, interfaces,
and bird crates increases the risk of farm contamination.
Most of the biosecurity practices that may contribute to
these risks are the same as those of the category II pathways
listed under Section 3.3.
The other notable factors found include the lack of
or non-adherence to biosecurity protocols at egg pack-
ing stations and feed mills, the non-thorough cleaning and
disinfection of the equipment, and multiple farm contacts
through the multiple deliveries per day and/or trip. These
companies expand the farm’s network, i.e., the number
of farms that are connected or linked to each other. An
example (from this study) of such a network expansion
is the scenario in which egg packing companies obtained
eggs from 100 and 150 farms with trays being exchanged
between these farms and their clients getting eggs from
other companies on the same day.
3.5. Category IV pathways: movements of persons and
equipment that only access the premises
These contacts include human contacts through input
and output deliveries (e.g., feed and bedding) as well as
manure pick-ups and having social gatherings of farm-
ers on farm premises. The premises-only human contacts
may also occur through the mentioned sale of eggs on the
premises (or even in the poultry houses) and/or through
delivery services of dead birds to the Central Veterinary
Institute (CVI) for further investigation. We also found that
only a few of the farms had biosecurity protocols for truck
drivers with many arguing that there was no need since the
drivers remained in the truck during most visits.
Premises-only contacts also include fomite contacts
through shared farm equipment. These fomites may
include the filling tube and the dust bags used during feed
delivery, egg trays, pallets and manure containers. Also,
the practice of allowing visitors to park on the premises
without separate parking increases the chances of premises
contamination as does the reported presence of other non-
poultry species on the premises.
The poultry-related company practices that render
these contacts risky are the delivery trucks lacking or not
7. 112 A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115
using the wheel disinfection systems that make multiple
deliveries. Another risky practice is the random distri-
butions of empty manure containers and egg trays. In
addition, the practice of allowing trucks from different
farms on the same company parking area at a given time
may increase the risk of truck contamination before their
subsequent visits. The already mentioned risk of expand-
ing the farm’s network (Section 3.4) also occurs through
the extended sourcing of manure from up to 850 farms by
the manure companies.
3.6. Category V pathways: neighbourhood risks
This category entails risks of indirect transmission
attributable to the nature and frequency of poultry-related
activities in the farm’s neighbourhood. Factors such as the
farm’s proximity to other poultry farms and water bodies
accessed by wild birds have been suggested to facilitate
virus transmission. We add to this list the farm’s proxim-
ity to poultry-related businesses and roads leading to these
businesses due to exposure through windborne dispersal.
More to that, the presence of uncovered manure stor-
ages and the use of manure on agricultural fields in the
neighbourhood of some of the interviewed farms further
increase their contamination chances. These factors are
facilitated by the lack of protection against contamination
by manure on all except four farms, one of which used a
6-m wide strip with trees around the premises as a barrier.
The resulting ‘neighbourhood risks’ may be facilitated by
movements between the field and the farm by other ani-
mals, rodents, insects, wild birds, humans (in cases where
contaminated dust colloids on their clothing and/or equip-
ment), vehicular traffic as well as wind dispersal.
We identified on-farm biosecurity and other practices
that may enhance these risks. These include poor farm
waste management (for example, disposing of untreated
waste water on the farm grassland or into the sewer sys-
tem). This together with the reported use of community
and well water (especially for cleaning the empty poultry
houses and equipment) may constitute a risk. Neighbour-
hood contamination risks may also arise from the practices
of the poultry-related businesses. For example, we found
that, at manure companies, manure was dried naturally and
stayed unprocessed on the premises for up to four weeks.
Furthermore, the waste management of some businesses
also contributes to neighbourhood risks. Transmission risks
may also arise from transport of materials and products
to and from the poultry-related businesses in the farm’s
neighbourhood. For example, the slaughterhouses that
took waste to a rendering plant up to 80 km away and
picked birds from as far as 300 km. Neighbourhood-related
risks may also be facilitated by the reported pet access to
poultry houses and storage rooms on some farms.
3.7. On the qualitative risk assessment
In Table 4 we present the outcomes of applying the
ranking scheme (Table 1) to the different contact types
identified in broiler and layer farms. We found that the
contact types deemed most risky comprise the thinning
and restocking contacts under category I, almost all human
contacts under category II, and the proximity to other
poultry farms under category V. Thinning and restocking
contacts ranked highly for two reasons namely, their prox-
imity to the birds being close and their frequencies being
quite high. On the other hand, the high rank for the human
contacts in category II was largely a consequence of their
enormous frequency. Generally, categories III and IV con-
tacts, due to their combination of category and frequency,
are hypothesized to pose a relatively medium overall risk
with no clear difference in exposure-risk between layer and
broiler farms.
4. Discussion
We conducted an in-depth interview study on the day-
to-day activities in the Dutch poultry industry with the aim
of identifying all exposure-risks resulting from between-
farm contacts (whether proximity related or due to visitors)
that are of potentially relevant to AI virus transmission
in the industry. Although some detailed results may be
specific to the Dutch situation, we expect that many of
our findings may be applicable to other countries with
a similarly structured poultry industry. On the one hand,
the interviewees were selected across all different poultry
husbandry types as well as poultry related businesses, in
order to collect responses about the full range of day-to-
day activities throughout the Dutch poultry industry. On
the other hand, the practices identified on the basis of a set
of sixty interviewed enterprises might obviously still not
be exhaustive.
A similar approach (of interviewing farmers about their
farm contacts and the accompanying biosecurity) has been
adopted in other recent studies. Examples include Dent
et al. (2008), Fiebig et al. (2009), Vieira et al. (2009), Dorea
et al. (2010), Leibler et al. (2010), Burns et al. (2011) and van
Steenwinkel et al. (2011) among others. Our approach of
conducting questionnaire-guided personal interviews had
the advantages of obtaining a 100% response rate as well
as providing the opportunity for a dialogue between the
interviewer and the respondent through which additional
information was obtained.
Perhaps surprisingly, the farmers perceived the risk of
AI virus introduction by the wild birds accessing water bod-
ies in farm neighbourhoods as being low. Furthermore, they
(farmers) had divergent visitor-risk opinions for all visitors
(Fig. 1). In particular, the result that many farmers attach a
low risk to the veterinarians may reflect a relationship of
trust. In line with this, most farmers do not force veterin-
arians to comply with biosecurity protocols (Table 3). One
observation relating to the possible actual risk posed by
veterinarians is that they were found to make more fre-
quent visits that involved accessing poultry houses and
storage rooms than, for example, the catchers (Table 4). A
high discrepancy between the reported and GIS extracted
numbers of poultry was also found. This information is vital
since the attitudes and knowledge expressed may influ-
ence the pattern of adherence to biosecurity protocols on
the farm.
We identified and categorized several human and non-
human between-farm contacts that can promote AI spread.
Given that biosecurity is among the main preventive
8. A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115 113
Table 4
Proposed exposure-risk classification for the different contact types for broiler and layer farms based on contact frequency, biosecurity practices and risk
category.
Risk category Contact type Broiler: average
number of contacts
per year
Layer: average
number of
contacts per
year
Proposed overall exposure-risk
classification based on contact
category and frequency:
broiler (layers)
Category I: movement of poultry between
farms
Restockinga
8 0.61 High (High)a
Thinning 4.8 0 High (Negligible)
Category II: contacts accessing poultry houses Veterinarian 24.1 1.2 High (High)
Feed mill
technician
24.1 7.8 High (High)
Hatchery/breeder
company
technician
2.9 4.1 High (High)
Repair technician 9.6 1 High (High)
Inspectors 1.9 1 High (High)
Vaccination crewsa
0 0.1 Not applicable (High)a
Catchersa
7.7 0.7 High (High)
Category III: contacts accessing storage rooms Veterinarian 27 1.3 Medium (Medium)
Feed mill
technician
27.0 8.9 Medium (Medium)
Hatchery/breeder
company
technician
7.7 4.2 Medium (Medium)
Repair technician 11.6 1 High (Medium)
Category IV: premises-only contacts Feed delivery 108.9 64.1 Medium (Medium)
Fuel delivery 3.2 1 Medium (Medium)
Bedding supply 4.4 1.7 Medium (Medium)
Farmer meeting 33.7 0.9 Medium (Low)
Presence of other
animalsb
6 farmsb
10 farmsb
Medium (Medium)
Category V: neighbourhood risks Proximity to
poultry farmsc
20c
37c
High (High)
Proximity to
poultry-related
businessesc
1c
2c
Medium (Medium)
a
The risk was adjusted to also cater for the number of people involved during the process, for example, a broiler farm is restocked by only the truck
driver and farmer whereas on layer farms, up to 25 people are involved in catching the pullets and delivering them.
b
Number of contacts per year estimated, the risk is derived based on the number of farms reporting the contact.
c
Number of contacts per year estimated, the risk is derived based on the number of farms or poultry-related businesses in the 5 km × 5 km neighbourhood.
measures against farm contamination through these con-
tacts, it is striking that our findings reveal inconsistency in
adhering to biosecurity protocols even against the already
‘known’ risks (Table 3). The identified obstacles to proper
biosecurity practices include absence of facilities, the non-
exhaustive protocols and non-adherence or inconsistent
application. On adherence, a similar inconsistency was
found in other recent studies on biosecurity implemen-
tation, for example Racicot et al. (2011) and Burns et al.
(2011).
The different transmission pathways we hypothesized
are deemed relevant for various reasons. Category I path-
ways (movement of poultry between farms) are important
due to the possibility of introducing infected birds on
the receiving farms. The infection in transported birds
(day-old chicks, pullets or older birds) may go unnoticed
for less virulent HPAI strains – for example the H7N7
A/Chicken/Netherlands/2003 (van der Goot et al., 2005)
that is less virulent compared to, for example, the H5N1
A/Chicken/Legok/2003 (Bouma et al., 2009) – or in case of
an LPAI strain. In pullets, LPAI infections can be present
without any clinical signs and virus transfer to another farm
or geographical area is possible during that time. We note
that, although vertical transmission has been reported for
turkeys (Jacob et al., 2011), the risk that infected hatch-
ing eggs may produce infected day old chicks is considered
low because the infected embryo is not likely to survive the
incubation process.
The other categories are deemed risky due to the pos-
sible direct introduction of infectious material into the
poultry house for category II, into the storage rooms for
category III and onto the premises for category IV related
contacts. The category III related contacts (both human and
fomite) may contaminate farm inputs (e.g., feed) if they
accessed contaminated material prior to the visit whereas
the category IV related contacts may require secondary
mechanisms to aid the transfer of infectious material from
the compound into the poultry houses. Pets, humans and
equipment may provide this link.
The frequency of all the contacts that constitute the
categories II and III pathways reported is enhanced by
the reported multi-site ownership which often comes
with increased sharing of labour and equipment as well
as the reported exchanges of personnel between farms
through visits by the farmers themselves, their family
members and the hired personnel. We also note that the
9. 114 A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115
reported practice (on some farms) of not having biosecurity
protocols for the delivery-truck drivers and only rely on the
fact that they always remain inside their trucks may expose
these farms to contamination on (emergency) occasions
that may require the driver to get out of the truck while
on the premises.
The presence of other animal species (both commercial
and pets) might also be relevant to AI introduction. This
is because of its associated activities such as the increased
number of farm visits through for example, feed delivery
and on-site veterinary care. Other than that, there is also
the possibility of these animals acting as vectors by trans-
porting contaminated material between locations as well
as the possibility of cross-species transmission. AI viruses
are known to affect hobby birds and other animal species
such as pigs, horses and cats (Röhm et al., 1995; Loeffen
et al., 2004; Belser et al., 2008) and are often less virulent
in other species of birds for example Pekin ducks (van der
Goot et al., 2008). If infected, some of these species (e.g.,
pets) have a chance of directly infecting poultry or con-
taminate feed since they were reported to access poultry
houses and storage rooms on some farms.
The several identified neighbourhood-transport related
risks may be additionally relevant when long distances
are covered thereby extending the geographical range
of neighbourhood contamination risks. Examples of long
distance transports reported include transports to slaugh-
terhouses and rendering plant. We note that such distances
are to be expected for the transports to the rendering plant
as there is only one rendering company in The Netherlands
that has only two destinations for carcasses.
The risk posed by neighbourhood-related contacts may
be controlled by, for example, reducing scavengers through
covering the manure storages that were reportedly left
open on some of the interviewed farms and/or ensuring
that manure does not stay long on the premises as well as
ensuring that dead birds are disposed of safely. In addition,
since dust acts as a vector on which the infectious material
colloids for dispersal, airborne contamination risks could
be reduced through installation of dust extraction systems
like air scrubbers. Such systems would help in reducing
contaminated dust emissions from poultry houses. More-
over, sprinkling oil in the poultry house may reduce the
amount of dust emitted, although this method is not very
user friendly. Additionally, measures to reduce the dis-
persal range of the emitted dust such as lowering the vent
height as well as measures that reduce the risk of a farm
letting in contaminated dust may lower the risks.
In the qualitative risk assessment, we focused on path-
ways identified in broiler and layer farms. Since the other
husbandry types had almost similar contact frequencies,
the risk ranking found (for layers and broilers) might not
differ significantly in the other types. Layer and broiler hus-
bandry types are the dominant poultry husbandry types in
The Netherlands and consequently were the most repre-
sented in the interviews. Due to data limitations, we cannot
draw firm quantitative conclusions about the actual risks;
the rankings made in this study have an indicative, quali-
tative character. We used the five categories of pathways
as a basis for this assessment. Note that, whereas the cate-
gorization helps to distinguish different levels of risk that a
single contact may pose, the overall risk for a given contact
type is a combination of the per-contact risk and the con-
tact frequency. Thinning and restocking both pose a high
risk although, unlike thinning, restocking on a broiler farm
is done by a small team (mostly the truck driver and the
farmer), requires less time and equipment and does not
involve intensive handling of animals.
Even though our results reveal that most exposure-risks
are almost similar for broiler and layer farms, during epi-
demics, for example the 2003 H7N7 HPAI epidemic in The
Netherlands (Stegeman et al., 2005) and the 2005 H5N2
LPAI in Japan (Nishiguchi et al., 2007), layer farms were
more likely to be affected. For the Dutch epidemic, the dif-
ference in risk may be explained by the relatively higher
density of layer farms compared to broiler farms in the
affected regions. We also emphasize that some of the rank-
ings may be altered during epidemics due to movement
restrictions.
Since poultry movement between farms poses the high-
est risk, we sought information about other relevant known
contacts to supplement the reported ones. We found that,
other than the reported movements during thinning and
restocking, poultry movements also occur a few days after
restocking when replacing the dead (early mortality) or the
small-size birds. They also occur when farms are getting rid
of the spent or old hens and/or when there are not enough
pullets on the farm. Some farmers also buy spent hens from
traders on rare occasions to increase their flock size.
All in all, our in-depth interviews facilitated the iden-
tification of several hitherto under-appreciated avenues
for AI virus transmission between farms that need to be
considered when designing or implementing prevention
strategies. The results of this study provide clues on the
possible mechanisms of virus transmission relating to the
various farm activities and neighbourhood characteristics.
The additional mechanisms hypothesized here can be put
into consideration when updating the manuals that guide
contact tracing during future epidemics.
We have found that there is currently widespread
non-adherence to existing biosecurity protocols. Our qual-
itative risk assessment results should help to prioritize
improvements in biosecurity. Our results, including those
on farmer opinions, are also relevant for the communi-
cation with farmers and poultry-related businesses about
practices and risks. We recommend that authorities and
sector organizations review the biosecurity protocols and
develop (intensified) communication strategies to encour-
age adherence to these. On-farm facilities designed to help
everyday adherence, such as walkways, barriers/fences and
warning signs, are currently often missing. Finally, the fre-
quency of risky visitor types should be reduced where
possible.
Acknowledgements
We are indebted to the farmers, company managers
and professionals who participated in this study, Phill te
Winkel, Albert Truin and Gerrie Hardeman for conduct-
ing the interviews and their contribution in developing
the questionnaires. We also thank Henriette Brouwer-
Middelesch (AHS) for entering the data in the database,
10. A. Ssematimba et al. / Preventive Veterinary Medicine 109 (2013) 106–115 115
Jan Workamp (AHS) and other AHS officials who provided
details on farm locations, Annemarie Bouma (ELI) and Peter
van der Velden (IvP) for their comments on the interview
questions, Gert Jan Boender (CVI) for the help with the
generation of maps, Linda McPhee for her comments on
the manuscript. This work was supported by the Foun-
dation for Economic Structure Strengthening (FES) in The
Netherlands: FES Program on Avian Influenza.
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