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.
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).
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.
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.
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.
AI transmission risks: Analysis of biosecurity measures and contact structureHarm Kiezebrink
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.
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.
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
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).
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.
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.
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.
AI transmission risks: Analysis of biosecurity measures and contact structureHarm Kiezebrink
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
5. swine flu influenza viruses a (h1 n1)Suresh Rewar
Flu viruses have mainly affected humans, birds and pigs worldwide. Influenza A viruses is highly infectious respiratory pathogens that can infect many species. The swine flu H1N1 reassorted subtype caused the first global pandemic in last 40 years, resulting in substantial illness, hospitalizations of millions of peoples and thousands of deaths throughout the world. There is no direct evidence that the reassortment events culminating in the 1918, 1957 or 1968 pandemic influenza viruses originated from pigs. Genetic reassortment among avian, human and/or swine influenza virus gene segments has occurred in pigs and some novel reassortant swine viruses have been transmitted to humans. The WHO declared the H1N1 pandemic on June 11, 2009, after more than 70 countries reported 30000 cases of H1N1 infection. Pandemic (H1N1) influenza most commonly causes a self-limited illness; however, significant morbidity and mortality were reported in the young, the obese and in pregnant women. The CDC recommends real time PCR as the method of choice for diagnosing H1N1. The U.S. Centers for Disease Control and Prevention recommends the use of Oseltamivir
(Tamiflu) or Zanamivir (Relenza) for the treatment. The drugs of choice for treatment and prophylaxis of pandemic (H1N1) influenza are the neuraminidase inhibitors, Oseltamivir and Zanamivir. In this review, a brief overview on swine flu is presented highlighting the characteristics of the causative virus, the disease and its public health consequences, advances made in its diagnosis, vaccine and control to be adapted in the wake of an outbreak.
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 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.
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.
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.
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.
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.
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.
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.
5. swine flu influenza viruses a (h1 n1)Suresh Rewar
Flu viruses have mainly affected humans, birds and pigs worldwide. Influenza A viruses is highly infectious respiratory pathogens that can infect many species. The swine flu H1N1 reassorted subtype caused the first global pandemic in last 40 years, resulting in substantial illness, hospitalizations of millions of peoples and thousands of deaths throughout the world. There is no direct evidence that the reassortment events culminating in the 1918, 1957 or 1968 pandemic influenza viruses originated from pigs. Genetic reassortment among avian, human and/or swine influenza virus gene segments has occurred in pigs and some novel reassortant swine viruses have been transmitted to humans. The WHO declared the H1N1 pandemic on June 11, 2009, after more than 70 countries reported 30000 cases of H1N1 infection. Pandemic (H1N1) influenza most commonly causes a self-limited illness; however, significant morbidity and mortality were reported in the young, the obese and in pregnant women. The CDC recommends real time PCR as the method of choice for diagnosing H1N1. The U.S. Centers for Disease Control and Prevention recommends the use of Oseltamivir
(Tamiflu) or Zanamivir (Relenza) for the treatment. The drugs of choice for treatment and prophylaxis of pandemic (H1N1) influenza are the neuraminidase inhibitors, Oseltamivir and Zanamivir. In this review, a brief overview on swine flu is presented highlighting the characteristics of the causative virus, the disease and its public health consequences, advances made in its diagnosis, vaccine and control to be adapted in the wake of an outbreak.
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
Influenza a emergency prepardness for healthcare facilitiesMoustapha Ramadan
The data presented are per 4th of March 2017 and subject to changes.
The presentation aims to provide the basic infection control requirement for healthcare facilities during large influenza epidemic or pandemic
Histopathology of Multiple viral infections in lung of camel (Camelus Dromeda...iosrjce
IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) is a double blind peer reviewed International Journal edited by the International Organization of Scientific Research (IOSR). The journal provides a common forum where all aspects of Agricultural and Veterinary Sciences are presented. The journal invites original papers, review articles, technical reports and short communications containing new insight into any aspect Agricultural and Veterinary Sciences that are not published or not being considered for publication elsewhere.
Avian influenza in herd health and production economicsShareef Ngunguni
Avian influenza is a zoonotic and notifiable disease which occurs world wide. Different risk factors are associated with transmission of the disease to humans. It has two forms HPAI and LPAI. The disease has an impact on public health and economics of the country. In Malawi,it seems the disease appeared in 2005 where it attacked migratory birds
Avian Influenza H7N9
Winnifred Brefo-kesse
Hlth 626
March 31, 2019
Professor Hughes
Part I: THE SITUATION ASSESSMENT
In February and March 2013, a novel influenza A (H7N9) virus emerged in China, causing an acute respiratory distress syndrome and occasionally multiple organ failure with high fatality rates in humans (Li et al., 2014). A total of 681 laboratory-confirmed cases and 275 deaths have been reported as of November 13th, 2015, with a fatality rate of 40% (http://www.who.int/influenza/human_animal_interface/HAI_Risk_Assessment/en/). H7N9 has been evolving and established amongst chickens in China over the past two years with occasional human infections (Lam et al., 2015; Su et al., 2015), thus posing a threat to public health. In the absence of an annually-updated effective vaccine, antiviral drugs constitute the first line of defense against H7N9 infections. H7N9 viruses already possess natural resistance to M2-ion channel blockers (amantadine and rimantadine) when it first emerged in 2013 (Gao et al., 2013). Therefore, neuraminidase inhibitors (NAIs), which include oseltamivir (TamifluH), zanamivir (RelenzaH) and peramivir constitute the main antiviral drugs against H7N9 infections (Hu et al., 2013; Wu et al., 2013). However, treatment with NAIs against H7N9 infections has resulted in the emergence of drug-resistant mutant viruses, as soon as 1~9 days after administration (Gao et al., 2013; Hu et al., 2013). Moreover, the first H7N9 isolate (A/Shanghai/1/2013(H7N9), SH-H7N9) was resistant to oseltamivir (Gao et al., 2013). Avian influenza A H7 viruses are a group of viruses that is mostly found amongst birds. The H7N9 virus is a subgroup of the H7 viruses and was recently discovered in China. There were three cases discovered in March of 2013 which ultimately increased in May by 132 cases. Of those cases, the 39 infected, died because of the virus (Peipei Song1, 2013). The clinical features described in the three patients with H7N9 virus infection, included fulminant pneumonia, respiratory failure, acute respiratory distress syndrome (ARDS), septic shock, multi-organ failure, rhabdomyolysis, and encephalopathy, are very troubling (Timothy M. Uyeki, 2013). As of now, this virus has reached stage two of three which is poultry passing the virus to humans. There is one more stage left which is human to human transmission which the Chinese health officials have confirmed it is not yet occurring. Creating an anti-virus takes a lot of time and until then public health officials should create new tactics in battling this epidemic.
Since there isn’t an anti-virus for the H7N9 virus, different health policies must be put in place to control the outbreak as well as preventative strategies from escalating. This vir.
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.
OIE terrestrial code killing of animals for disease preventionHarm Kiezebrink
The guidelines are intended to help countries identify priorities, objectives and the desired goal of disease control programmes.
Disease control programmes are often established with the aim of eventual eradication of agents at a country, zone or compartment level. While this approach is desirable, the needs of stakeholders may require a broader range of outcomes.
For some diseases, eradication may not be economically or practically feasible and options for sustained mitigation of disease impacts may be needed.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
2. Introduction
Avian influenza A viruses are highly heterogeneous, with varying pathogenicity across different
species. They are classified into subtypes based on the surface glycoproteins haemagglutinin
(HA) and neuraminidase (NA). Pathogenicity of the virus in chickens is related to the patho-
type: low-pathogenic avian influenza (LPAI) viruses can contain any type of HA, while highly
pathogenic avian influenza (HPAI) viruses invariably contain H5 or H7 [1]. Mortality is a
prominent sign of HPAI-infected flocks, whereas LPAI-infected flocks show milder or even
subclinical signs that can wax and wane, making LPAI more difficult to detect.
In wild birds, avian influenza virus is primarily transmitted through fecally contaminated
surface water in shared aquatic habitats. In these habitats, the viruses can persist for extended
periods, depending on water temperature and physico-chemical characteristics [2]. In domesti-
cated birds, or poultry, HPAI viruses are typically found in both feces and respiratory secre-
tions, while LPAI viruses are mainly shed through the enteric route [3]. Virus-contaminated
droppings serve as source of infection for susceptible birds, and influenza viruses can remain
infectious for many days in poultry litter [4, 5]. Dispersal of infectious material into the envi-
ronment may occur through ventilation of virus-contaminated dust. In commercial poultry
operations, concentrations of airborne dust are high and include a large component of fecal
material along with food, dander (skin material), feather material, and micro-organisms [6].
Detection of influenza A virus in air measurements collected within farms suggest that particu-
late matter from infected poultry may play a role in avian influenza virus transmission to hu-
mans and birds, and other animals [7, 8].
One of the routes for pathogen transmission is through dispersal into outdoor air. Viruses
may be dispersed as single particles or by using other particles (particulate matter) as a vehicle
[9–11]. Recently, Ypma et al. estimated that wind direction could explain about 18% of the
total transmission of avian influenza between farms during an outbreak of influenza A(H7N7)
virus in 2003 [12]. However, wind direction alone does not quantify the amount of pathogen
transmitted to a certain distance, as wind speed is another important factor [13]. Atmospheric
dispersion models (ADMs) take these and other factors into account and have been applied to
analyse the correlation between airborne pathogen transmission and the incidence of disease in
the nearby surroundings for Legionella pneumophila [14], foot-and-mouth disease [15], Cox-
iella burnetii [16], and avian influenza virus [17]. Although the ADM data are suggestive of air-
borne pathogen dispersion, laboratory data have not yet confirmed that airborne avian
influenza viruses are indeed detectable in the air downwind of a source.
Previously, we demonstrated that farm-to-farm spread of avian influenza viruses was associ-
ated with accumulated mutations that increase the public health risk of HPAI A(H7N7) viruses
[18]. In addition, LPAI virus replication in poultry may trigger the emergence of an HPAI vari-
ant by alteration of the HA cleavage site, facilitating systemic infections. The consequent im-
portance of early control of outbreaks became very clear with the 2013 emergence of avian
influenza A(H7N9) viruses in China. Despite causing severe illness in humans, these viruses
have the LPAI phenotype, making it hard to identify the avian sources and rendering humans
as sentinels [19–21]. Gaining more insight into the transmission routes of avian influenza will
help provide a more solid basis for current outbreak response strategies, and thereby could
eventually reduce the public health risk associated with outbreaks.
In this study, we collected samples of suspended particulate matter, or inhalable dust frac-
tion, inside, upwind and at several distances downwind of buildings holding poultry infected
with LPAI. The samples were tested for the presence of influenza virus and for endotoxins, a
marker for microbial exposure of poultry and livestock, since they have a high presence in com-
mercial farms and can be quantified in the adjacent outdoor air [22]. We hypothesized that
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 2 / 15
3. particulate matter may be used as a substitute for dispersion monitoring of avian influenza
transmitted into the environment during outbreaks [10]. Consequently, airborne microbial ex-
posure was determined by measuring endotoxin concentrations at different distances from
farms and compared with an ADM to test the applicability of this model for the rapid charac-
terization of a geographical region exposed during future outbreaks of avian influenza.
Materials and Methods
Farm description
At the following five LPAI-infected farms and one control farm, air samples were taken at mul-
tiple distances from the farms.
Farm 1 was a naturally ventilated organic chicken farm composed of an indoor-housed
flock and a free-range flock. An LPAI A(H7N7) virus infection was detected by targeted inves-
tigation following signs of reduced food consumption, diarrhea, and limited growth of 8900
22-week old chickens. All chickens were culled on the day of confirmation of virus presence, in
accordance with European guidelines for avian influenza virus subtypes H5 and H7 in com-
mercial poultry (EU directive 92/40/EEC). Outdoor air sampling was initiated approximately
six hours after the culling, at locations upwind and downwind of the farm.
Farm 2 was a mechanically ventilated turkey farm with 20,600 one-month old turkey chicks.
It was tested for the presence of influenza virus because of negative health reports, showing in-
fection with LPAI A(H9N2) virus. Nine days after sampling of the birds, air sampling was per-
formed at locations upwind and downwind of the farm. No control measures were applied
following outbreak confirmation, in accordance with EU guidelines.
Farm 3 was a bird-breeding farm that also housed various mammals and reptiles. Air was
sampled upwind and downwind of 83 healthy-appearing wild swans that had been captured
and were destined for export to a foreign zoo. The swans were quarantined following a positive
screen for LPAI A(H5N2) virus performed as part of export guidelines. The air sampling was
performed eleven days after A(H5N2) virus-positive cloaca swabs were collected. Twenty-
four days after the initial A(H5N2) virus was detected, cloaca swabs indicated a continuing
infection.
Farm 4 was a mechanically ventilated turkey farm housing three flocks: two with a total of
4000 21-week-old hens and one with 18,000 one-week-old chicks. In the hens, an LPAI A
(H10N9) virus infection was detected following reports of reduced food consumption, respira-
tory signs including coughing, and malaise. Air sampling was performed at downwind loca-
tions nine days after the A(H10N9) virus-positive cloaca and trachea swabs were collected. No
control measures were applied following outbreak confirmation.
Farm 5 was a mechanically ventilated mixed farm composed of two turkey flocks and a
number of pigs. One turkey flock included 4000 20-week-old turkey cocks; the other included
an unknown number of chicks. An LPAI A(H10N9) virus infection was detected following re-
ports of increased mortality, nasal discharge, and respiratory signs in the 20-week-old turkeys.
Air sampling inside and at downwind locations of the barn was performed three days after the
A(H10N9) virus-positive cloaca and trachea swabs were collected. No control measures were
applied following outbreak confirmation.
Farm 6, included as a control, was a naturally ventilated turkey farm that housed 16,500
one-month-old chicks. It was chosen because it was relatively isolated, with no commercial tur-
key farms (closest at ± 10 km) or chicken farms (closest at ± 4 km) in the immediate surround-
ings. In addition, the distance to nearest other livestock farms was >1 km. Air sampling was
performed at downwind locations.
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 3 / 15
4. Environmental samples
Environmental sampling was performed either on private land with permission of the owner
or on public roads requiring no permissions. The experiment did not involve endangered or
protected species.
Airborne inhalable dust samples were initially captured on a 37-mm diameter Teflon filter
with a pore-size of 2.0 μm (SKC, PA, USA) using the GSP personal sampler (JS Holdings, Ste-
venage, UK) equipped with a conical inlet with an 8-mm diameter orifice at the front. The sam-
pler meets the CEN/ISO/ACGIH criterion for inhalable dust when operated at 3.5 L per
minute, which was achieved with a constant-flow pump (Gill air 5, Gillian, UK). Using a tri-
pod, sampling was performed 1.5 m above ground for a six-hour period, resulting in a filtered-
air volume of 1.3 m3
. Multiple GSP samplers were used for simultaneous collection of inhalable
dust samples at several distances from a farm. Immediately after sampling, the GSP sampling
heads were wrapped in plastic before transport from field to laboratory, where they were stored
at −20°C until further use.
In addition to the six-hour GSP air-sampling strategy, a short-term strategy using a portable
air sampler was incorporated halfway into this study. The short-term air samples were ob-
tained with an MD8-AirPort Air Sampler (Sartorius, Göttingen, Germany) equipped with cel-
lulose nitrate filters having a pore size of 8 μm. This sampler was operated at 50 L per minute,
with a sampling time of 20 minutes, resulting in a filtered-air volume of 1.0 m3
. One MD8-Air-
Port sampler was used for consecutive collection of air samples at several distances from a
farm. Immediately after sampling, each cellulose nitrate filter was transferred to a sterile Petri
dish before transport from field to laboratory and storage at −20°C [23, 24].
Influenza virus recovery
Our procedure for the detection of airborne influenza viruses was adopted from knowledge
gained during a Q fever outbreak. We therefore evaluated whether the method for detecting
Coxiella burnetii DNA in inhalable airborne dust collected on Teflon filters could be used for
recovery of influenza virus by reverse transcriptase PCR (RT-PCR), using cell-culture grown
influenza virus as a control [25]. We used three additional filter extraction procedures to deter-
mine which allowed the most sensitive RT-PCR detection of influenza viruses on filters.
To each filter we applied 20 individual 5-μL drops of heat-inactivated LPAI virus A/Mal-
lard/NL/12/2000 (H7N3) in Dulbecco's modified Eagle medium (Gibco, NY, USA), corre-
sponding with 1.3 x 105
influenza genome copies [26]. The filters were air-dried and shaken for
one hour in 4 mL pyrogen-free water with 0.05% Tween 20 (Calbiochem, CA, USA), with
(method A) or without (method B) subsequent enzyme treatment intended to free bacterial
DNA. Enzyme treatment consisted of adding 100 μL of 1 mg/mL lysostaphin (Sigma, MO,
USA) and 20 μL of 20 mg/mL lysozyme (Sigma) followed by incubation for 35 minutes at
37°C, after which 400 μL of 20 mg/mL proteinase K (Roche diagnostics, Rotkreuz, Switzerland)
was added and incubated for 10 minutes at 55°C. Enzymes were then heat-inactivated at 95°C
for 10 minutes. This step was followed by DNA/RNA extraction using the NucliSens Magnetic
Extraction Kit (bioMérieux, Marcy-l'Etoile, France) according to the manufacturer’s instruc-
tions [25].
Alternatively, spiked filters transferred to 2mL Eppendorf tubes containing 1 mL PBS and
1% Triton X-100 (BDH Chemicals, Poole, UK) were vortexed 3x10 seconds (method C), were
mixed using a bench rocker for 30 minutes (method D) or sonicated for 30 minutes (method
E), followed by RNA extraction as described below. For use as reference material, 100 μL influ-
enza A/Mallard/NL/12/2000 (H7N3) virus was directly resuspended in 900 μL PBS and 1%
Triton X-100. All procedures were performed in triplicate.
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 4 / 15
5. The presence of influenza virus was measured by a real-time influenza virus-specific
RT-PCR as described below [26]. All obtained cycle-threshold (Ct) values were within the line-
ar part (R2
= 0.9995) of the RT-PCR amplification. Influenza virus recovery was calculated by
comparing the averaged Ct values per extraction procedure with the averaged Ct values of the
reference material. The method with highest recovery was used in subsequent experiments.
Environmental air sample processing
The Teflon filters (37mm diameter) collected from the GSP after air sampling were cut in half
and transferred to 2 mL Eppendorf tubes prefilled with either 1 mL PBS containing 1% Triton
X-100 or 1.5 mL infection medium consisting of Modified Eagle Medium with Hanks' BSS
(BioWhittaker, Verviers, Belgium) supplemented with 10% PGR-albumin, penicillin, strepto-
mycin, nystatin, L-glutamine, HEPES, and trypsin. The larger cellulose nitrate filters (80mm
diameter) were likewise cut in half and transferred to 15-mL Greiner tubes prefilled with either
1.5 mL PBS containing 1% Triton X-100 for molecular testing, or 5 mL infection medium. Fil-
ters in infection medium were vortexed for 10 seconds followed by 0.22 μm filtration, and
300 μL (Teflon) or 2 mL (cellulose nitrate) of the flow-through was subsequently used for
virus isolation.
Detection of influenza virus
RNA was extracted from 600 μL of the recovered fluids from Triton X-100-treated Teflon and
cellulose nitrate filters using the High Pure RNA isolation Kit (Roche), and influenza virus
real- time RT-PCR was used to detect the matrix gene of the influenza virus [26, 27]. The influ-
enza virus RT-PCR had a linear amplification range up to Ct value 31.15, corresponding with a
limit of quantification of 1.1 x 104
genome copies per ml or 3.0 x 102
50% egg infectious dose
(EID50) per ml. The detection limit of the influenza virus RT-PCR was 320 genome copies per
ml or 8.9 EID50 per ml.
Influenza virus isolation
Filter-rinse fluids in infection medium were cultured on tertiary cynomolgus monkey kidney
cells [28] and maintained in culture for a maximum of 2 weeks, or until cytopathic effect was
observed. Presence of influenza virus in the culture supernatants was verified by RT-PCR as de-
scribed above. The foregoing is standard procedure for human influenza virus isolation in our
laboratory, which was proven effective for the isolation of avian influenza viruses during the in-
fluenza A(H7N7) virus outbreak in the Netherlands in 2003 [29]. Consequently, we hypothe-
sized that it could be used to isolate avian influenza virus from filter fluids.
Endotoxin measurement
In addition to influenza virus RNA, air samples obtained from farms 4, 5 and 6 were assayed
for endotoxins, which can serve as a generic proxy for airborne poultry and livestock associated
microbial exposure [22]. Endotoxin content of fluids from Triton X-100-rinsed filters was ana-
lyzed by the quantitative kinetic chromogenic Limulus amebocyte lysate (LAL) assay, described
previously [30]. Inhibition or enhancement of the LAL-assay by application of 1% Triton X-
100 was verified in dilution series, but was not observed when samples were diluted at least
1:50 in the assay. Consequently, fluids from Triton X-100-rinsed filters were tested in a dilution
of 1:50 or higher. Results were expressed as endotoxin units (EU) per m3
(18EU = 1ng). The
limit of detection was 1 and 2 EU per m3
of filtered air for the GSP and MD8-AirPort
measurements, respectively.
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 5 / 15
6. Detection of turkey cells
In addition to the quantification of endotoxins as a generic proxy for airborne microbial expo-
sure, PCR detection of the Meleagris gallopavo (turkey) gene for mitochondria cytochrome oxi-
dase 1 (CO1) was performed as a turkey farm-specific proxy for airborne exposure. Of fluids
from Triton X-100-rinsed filters, 200 μL was used for automated total nucleic acid isolation on
a MagNA Pure 96 extraction robot (Roche) with the MagNA Pure 96 DNA and Viral NA
Small Volume Kit. Next, a real-time PCR assay was performed, targeting a 90-nucleotide frag-
ment of the CO1 gene, using LightCycler 480 DNA SYBR Green I Master and the primers
TurkeyCOI-F (5’-ACAACCATATTCTTATCATTAACC-3’) and TurkeyCOI-R (5’-GTTGCA
TTAAGTATAGGTGTTT-3’).
Atmospheric dispersion model (ADM)
We compared the endotoxin measurements to relative spatial particulate matter concentra-
tions calculated by the atmospheric dispersion model OPS-ST (Operational Priority Sub-
stances, Short Term) model, version 4. This ADM was developed by the Dutch National
Institute for Public Health and the Environment (RIVM) for the dispersion modeling of chem-
ical pollutants, i.e. particulate matter and ammonia/nitrogen oxides generated by traffic, indus-
tries, agriculture, and natural sources [31–33]. The OPS-ST model downloaded hourly-
averaged meteorological data from the Royal Netherlands Meteorological Institute webserver,
including wind speed, wind direction, solar radiation, temperature, precipitation amounts, and
precipitation duration [33, 34]. We used coarse particulate matter as a proxy for endotoxin and
assumed an environmental roughness length of 20 cm.
We defined the farms under investigation as point sources in the OPS-ST model, with arbi-
trary PM10 emission amounts per hour per source from 10:00AM to 16:00PM on sampling
days. We calculated the concentrations at an above-ground height of 1.5 m on a grid of 2 x
2 km, with a grid-cell size of 10 m. Since we converted the modeled concentration levels relative
to the concentration near the source, we were able to compare these modeled data to measured
endotoxin concentrations by performing a linear regression analysis.
Results
Influenza virus recovery
Influenza virus recovery measured by RT-PCR was 10% when Teflon filters were processed by
using method A, but recovery increased to 43% in the absence of enzyme treatment (method
B). Rinsing of filters with PBS containing 1% Triton X-100 using the alternatives of vortexing
(method C), a bench rocker (method D), or sonication (method E) resulted in influenza virus
recovery of 60%, 26% and 57%, respectively. Based on these results, all filters were processed
using method C prior to RNA extraction and influenza virus detection by RT-PCR.
Influenza virus detection
As the applied influenza A virus RT-PCR demonstrated a limit of detection of approximately 6
genome copies per reaction, the processing of filter-rinse fluids combined with the available
virus recovery data led to a theoretical limit of detection of approximately 300 and 500 influen-
za genome copies per m3
of filtered air for the GSP and MD8-AirPort measurements, respec-
tively. Influenza A viruses could be detected by RT-PCR in outdoor-air samples obtained up to
60 meters downwind of commercial turkey farms 2, 4 and 5, which had ongoing LPAI infection
(Table 1). However, the corresponding Ct values were high and beyond the linear RT-PCR am-
plification range (Ct value > 31.15), hampering virus quantification except for an indoor-air
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 6 / 15
8. sample from farm 5 that had an influenza virus concentration of 8.48 x 104
genome copies
per m3
. The air measurements initiated approximately six hours after the culling of farm 1
yielded no influenza virus. In addition, none were detected in the filter fluids from the air mea-
surements obtained near the LPAI-positive swans at farm 3 or near control farm 6. Despite the
fact that some of the air filters tested positive for influenza virus RNA, the GSP and MD8-Air-
Port filters yielded no virus isolates.
Endotoxin measurement
For farms 4, 5 and 6, fluids from Triton X-100-rinsed filters were likewise tested for the amount
of air-suspended endotoxins (Table 1; Fig 1). As expected, endotoxin concentrations decreased
as function of distance from the source, suggesting a reduction in microbial exposure with in-
creasing distance. Air samples taken outside poultry barns had endotoxin concentrations of
~50 EU/m3
at distances up to 50 meters from the farm. At 100 meters and further from the
farm, endotoxin concentrations decreased to <10 EU/m3
. The highest endotoxin concentra-
tions detected in outdoor-air samples corresponded with two MD8-AirPort measurements at
poultry farm 5, probably influenced by emissions from a nearby upwind-located pig shed with
an indoor endotoxin level of 99.000 EU/m3
.
Table 1. (Continued)
Farm
No.
species virus
subtype
air sample
type
distance
from barn
bearing
from barn
type of
measurement
influenza
virus (Ct
value)
turkey
COI (Ct
value)
Endotoxin
EU/m3
OPS
conc.
(log)
MD8:
Cellulose
nitrate
44m 42° downwind neg neg 15.21 -1.00
MD8:
Cellulose
nitrate
100m 47° downwind neg neg 7.47 -1.89
MD8:
Cellulose
nitrate
110m 59° downwind; rain neg neg 2.60 -1.59
MD8:
Cellulose
nitrate
110m 50° downwind neg neg 7.07 -1.81
MD8:
Cellulose
nitrate
160m 85° downwind neg neg 5.00 -1.45
MD8:
Cellulose
nitrate
190m 40° downwind neg neg * -2.35
MD8:
Cellulose
nitrate
200m 55° downwind neg neg * -2.18
MD8:
Cellulose
nitrate
410m 71° downwind neg neg 3.82 -2.37
nd) not determined
*) Below detection limit
#) outside plume
doi:10.1371/journal.pone.0125401.t001
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 8 / 15
9. Detection of turkey cells
The presence of air-suspended turkey cells was confirmed in samples obtained from farms 4
and 5 (Table 1). The three downwind dust samples collected closest to the farm tested positive
for the turkey cells. However, at distances 10 m, turkey cell concentrations reached the limit
of CO1 detection.
Atmospheric dispersion modeling of particulate matter
Fig 2A shows the modeled relative concentrations of particulate matter at farms 4, 5 and 6. We
next determined the modeled concentrations at the locations of air sampling (Table 1) and
plotted them against the corresponding endotoxin concentration of each air filter location (Fig
2B). Air filters exposed to rain, located outside the dust plume, or showing an endotoxin con-
centration below the limit of detection were excluded. In general, endotoxin measurements
and modeled relative concentrations of particulate matter showed a good correlation: linear re-
gression analysis for farms 4 and 5 resulted in slopes of 0.72 (95% CI: 0.09 – 1.55) and 0.78
(95% CI: 0.08 – 1.64), respectively, and an R2
of 0.88 and 0.61, respectively. Analysis of farm 6
resulted in a slope of 0.45 (95% CI: 0.02 – 0.88) and an R2
of 0.59. Combining the data of farms
4, 5 and 6 resulted in an overall slope of 0.69 (95% CI: 0.42 – 0.97) and an R2
of 0.65.
Discussion
We demonstrate the wind-mediated spread of influenza virus-contaminated poultry dust into
the environment during influenza outbreaks in commercial poultry farms based on detection
of the air-suspended virus downwind of farms. The observed influenza virus concentration of
8.5 x 104
genome copies per m3
air inside turkey farm 5 is in agreement with previous reports
of 6.9 x 104
influenza virus particles per m3
detected in chicken houses and 3.7 ×104
particles
per m3
in a chicken pen, respectively [7, 8]. As the mechanical ventilation rates of commercial
poultry housing range from a minimum of 0.5 m3
/kg/hr up to 4.0 m3
/kg/hr, the amount of air
that is forced into the environment was at least 40.000 m3
per hour for farm 5, corresponding
Fig 1. Endotoxin concentrations in air samples outside poultry barns are depicted in relation to the
distance from the poultry barn, illustrating a reduction of airborne endotoxin with increasing distance
from the source.
doi:10.1371/journal.pone.0125401.g001
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 9 / 15
10. Fig 2. Dispersion of particulate matter around poultry farms, based on field measurements of endotoxin concentrations in air samples and
OPS-ST particulate matter modeling. A) Maps illustrating the air sampling locations together with the atmospheric dispersion of particulate matter (relative
to the source) that was modeled using meteorological data corresponding with the day and timeframe (10:00AM—16:00PM) of air sampling. B) Scatterplot of
modeled dispersion and measured endotoxin concentration. Qualitative results of influenza virus RNA and turkey cell DNA detection are depicted as well.
doi:10.1371/journal.pone.0125401.g002
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 10 / 15
11. with the emission of over 3 x 109
influenza virus genome copies per hour. A very large volume
of virus particles could be shed into the environment during an outbreak, particularly with a
source of prolonged emission like farm 4, where the infection started two weeks before the pos-
itive air samples were obtained. Such geographic dispersal of airborne virus may explain the de-
tection of influenza virus RNA in, for example, dust swabs and samples of soil and mud
puddles taken in areas surrounding farms positive for influenza A(H5N1) virus [35].
A crucial question when using this data for risk assessment is whether the viruses remain in-
fectious during dust-mediated dispersal. We did not detect any infectious virus in our study,
perhaps due to the sampling procedure. Mandal and Brandl (2011) have shown that dehydra-
tion stress caused by filtration reduces survival rates of bacteria [36]. Likewise for influenza vi-
ruses, filtration was found to reduce viability [37, 38]. Even when air is not passed through a
filter, infectious influenza virus can decay with a 1–2 log reduction after drying at room tem-
perature [39, 40]. Filtration and the subsequent processing of samples is therefore not optimal
for the detection of live microorganisms, although Spekreijse et al. demonstrated that using a
less dehydrating filter medium like gelatin allows detection of infectious influenza viruses in
air-filter samples [41]. In our study, environmental conditions could also have led to influenza
virus inactivation. Finally, virus recovery may have been reduced by 0.22 μm syringe filtration
of the inoculum prior to cell culture inoculation, to minimize bacterial contamination. Our re-
sults are in agreement with the RT-PCR detection of swine influenza at locations downwind
from swine farms using liquid cyclonic collectors, for which virus infectivity could not be con-
firmed, possibly due to low virus loads combined with physical disruption of viruses during air
sampling [42].
In addition to virus detection by RT-PCR, the presence of turkey-specific CO1 gene was
confirmed by PCR. Although this proxy for airborne microbial exposure is specific for turkey
(farms), it appeared to be less sensitive than the generic endotoxin proxy. Nevertheless, the as-
sociation between detectable virus and host nucleic acids illustrated the potential application of
CO1 gene sequencing to assess sources of zoonotic agents in environmental samples.
Data from the six-hour measurements with GSP personal samplers confirmed the presence
of influenza virus in the inhalable dust fraction of outdoor air near infected poultry farms. In
addition to the approximately 106
microbial cells present in 10 m3
air that humans inhale dur-
ing the course of a day [36], our data suggests that humans living downwind of influenza virus-
positive farms are possibly exposed to these virus particles. Unfortunately, our use of low-vol-
ume air samplers resulted in the detection of unquantifiable influenza virus RNA in the out-
door air. The use of high-volume air samples will presumably provide data that are more
robust and allow outdoor air characterization at larger distances from an infected barn. In ad-
dition to the characterization of wind-borne influenza virus exposure, determining the infectiv-
ity of wind-borne influenza virus is challenging. Due to the loss of virus viability by air
sampling methods, placement of naïve sentinel animals at a grid downwind of infected poultry
farms is the method of choice to obtain relevant and conclusive data on the public health im-
pact of wind-borne influenza virus spread. Such data can also be gained by sero-surveillance
studies of humans and animals previously exposed to the virus.
As the average size of single influenza virus particles is 80 – 120 nm, our capture of viruses
with 2.0 μm and 8.0 μm pore-sized filters suggests that these virus particles are indeed dis-
persed using other particles (particulate matter) as a vehicle [9–11, 43]. However, the mesh of
fibers in aerosol filters (including Teflon and cellulose nitrate filters) enable efficient collection
of much smaller particles than their pore-size would indicate [44]. Consequently, more re-
search is needed to characterize the particle size distribution in relation to the detection of in-
fluenza virus RNA. Although the amount of influenza virus RNA in outdoor air near barns was
unquantifiable, airborne poultry and livestock associated microbial exposure was determined
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 11 / 15
12. by measuring concentrations of endotoxin. Endotoxin concentrations measured at different
distances from farms were compared with modeled concentrations of particulate matter. De-
spite the many variables that potentially influenced the relationship between emission of parti-
cles and concentration, a good correlation between field measurements and modeled
particulate concentrations was observed (Fig 2B). Although the 95% confidence intervals of the
slopes corresponding with individual farms were large, combining all farms reduced the confi-
dence interval, possibly by averaging out errors.
Our results suggest that an ADM like the OPS-ST model could be used to model the disper-
sion of outdoor airborne pathogens prospectively. However, the quantitative model outcomes
should be regarded as indicative, given the number of unknown uncertainty factors. For exam-
ple, the model predicts dispersion of PM10 while it is yet unknown what proportion of influen-
za viruses are associated with the PM10 fraction of airborne particulate matter. Nor is it known
how the pathogens are distributed over the different size fractions within PM10. Although an
association was found between modeled and measured concentrations, the slopes in Fig 2B did
deviate from 1, suggesting that dispersion is slightly different for endotoxins than for modeled
dust. The difference should be clarified in future studies. Moreover, it should be noted that
virus inactivation (e.g., as a result of UV-radiation or dehydration) is not included in the
model. Since our measurements were performed at relatively short distances from the infected
farms, absence of an inactivation rate will not lead to high biases. At larger distances, however,
the inactivation rate will be more important and must be included when this type of informa-
tion becomes available.
In accordance with EU directive 92/40/EEC, controlling outbreaks of HPAI viruses relies on
movement restrictions for farms within a radius of at least 10 km of an infected farm, along
with culling of infected poultry. Depending on the outbreak severity, additional control mea-
sures can be taken including preventive ring-culling of farms within a (1–5 km) radius of an in-
fected farm and extended (nationwide) standstill for the transport of live poultry. Despite such
measures, avian influenza virus outbreaks in areas with high concentrations of poultry have
been difficult to control, resulting in large-scale culling in the Netherlands, Canada and Mexico
[45–47]. More directed interventions can potentially limit the duration of the outbreak and the
number of culled farms [48]. Gaining insight on farm-specific virus spread allows directed in-
terventions following targeted surveillance.
In this study, we demonstrated the presence of airborne influenza virus RNA downwind
from buildings holding LPAI-infected birds, and 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 expo-
sure 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 in-
fluenza 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 re-
duced both by minimizing the initial generation of airborne particles and implementing meth-
ods for abatement of particles once generated [6, 49]. 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 [50, 51].
Wind-Mediated Spread of Avian Influenza Viruses
PLOS ONE | DOI:10.1371/journal.pone.0125401 May 6, 2015 12 / 15
13. Author Contributions
Conceived and designed the experiments: MJ JvL IW AM MK. Performed the experiments: MJ
JvL. Analyzed the data: MJ JvL. Contributed reagents/materials/analysis tools: MJ JvL GK.
Wrote the paper: MJ JvL IW GK AM MK.
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