This document summarizes a quantitative microbial risk assessment (QMRA) that investigated the potential public health risk of transmission of ESBL-producing Escherichia coli and Campylobacter bacteria from poultry farms to humans through flies. The study modeled human exposure based on the fraction of contaminated flies leaving infected poultry farms, the number of bacteria per fly, and the number of positive poultry houses in the Netherlands. It compared the risk estimates to consumption of chicken fillet and found that transmission of both pathogens through flies may be an important transmission route worthy of further modeling and investigation given the potential public health implications.
Avian flu Type A-H5N1 epidemiological model: Puerto Rico as a case studyMariangeles Rivera
This document outlines research on modeling the potential spread of avian influenza A-H5N1 between two cities in Puerto Rico. The objectives are to determine potential outbreaks using a metapopulation network approach in a SIR model for Cayey and Aibonito. The methodology implements a mobility model coupling differential equations for the human populations. Parameters include infection and recovery rates. Future work involves simulations under different scenarios and expanding the model to include more towns. Acknowledgments recognize the University of Puerto Rico at Cayey and mentor for the opportunity.
Livestock disease drivers, ecology and pathogen evolutionEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
This document presents a mathematical model to eliminate malaria transmission by breaking the life cycle of Anopheles mosquitoes. The model introduces two natural enemies - copepods to prey on mosquito larvae and tadpoles to prey on pupae. Differential equations were derived to model the growth of each mosquito life stage from egg to adult when under attack by these predators. Stability analysis of the disease-free equilibrium was conducted using equilibrium points, Beltrami's conditions, and Diekmann's conditions. The results indicate that introducing copepods and tadpoles makes the disease-free equilibrium stable, meaning the mosquito life cycle would be broken and no adult mosquitoes emerge to transmit malaria.
Relations between pathogens, hosts and environmentEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
Malaria is caused by parasites transmitted through mosquito bites. It affects over 200 million people annually and causes over 1 million deaths. Biotechnology research is working to develop new treatments, such as vaccines and drugs targeting different stages of the parasite's lifecycle. Detection of malaria has also advanced through new diagnostic tests identifying parasite biomarkers using techniques like monoclonal antibodies and real-time PCR. While progress has been made, drug resistance remains a major challenge, and continued biotechnology research is needed to control and eliminate malaria worldwide.
This document describes a study examining options to control Lyme disease in Doctor's Park in Milwaukee County, Wisconsin. A simulation model was used to estimate tick populations based on mammal populations that ticks feed on. Simulations reduced populations of individual species and combinations of species. Results showed that reducing small rodent populations like mice and chipmunks by 50% combined with increasing red fox populations reduced infected ticks per hectare the most, to less than 1% of the baseline. Reducing nuisance species like raccoons increased infected ticks.
The Evolution of Viral Pathogens in Veterinary Medicine: Canine Parvovirus an...Kara Moloney
Viral pathogens like canine parvovirus (CPV) and canine influenza virus pose challenges for veterinary medicine due to their ability to rapidly evolve. CPV emerged in 1978 and has since evolved into multiple variants, including CPV-2a, CPV-2b, and CPV-2c. These variants differ in their viral capsid protein VP2, which affects host specificity. Canine influenza is an influenza A virus that crossed over from equines to canines in 2004. While not causing major outbreaks like CPV, it still poses a threat through potential evolution. Both viruses continue adapting transmissibility and host range through genetic mutations under selection pressure.
The study investigated the transmission of Salmonella enterica, Cronobacter sakazakii, Escherichia coli O157:H7, and Listeria monocytogenes from adult house flies to their eggs and first filial (F1) generation adults. The researchers fed adult house flies food contaminated with low, medium, and high levels of each pathogen. They found that all pathogens were present in samples of pooled house fly eggs. Transmission was highest when adults consumed medium bacterial loads. Cronobacter sakazakii was most likely to be transmitted to eggs. S. enterica and C. sakazakii were transmitted to F1 adults and more likely to be found on their surfaces than in their guts
Avian flu Type A-H5N1 epidemiological model: Puerto Rico as a case studyMariangeles Rivera
This document outlines research on modeling the potential spread of avian influenza A-H5N1 between two cities in Puerto Rico. The objectives are to determine potential outbreaks using a metapopulation network approach in a SIR model for Cayey and Aibonito. The methodology implements a mobility model coupling differential equations for the human populations. Parameters include infection and recovery rates. Future work involves simulations under different scenarios and expanding the model to include more towns. Acknowledgments recognize the University of Puerto Rico at Cayey and mentor for the opportunity.
Livestock disease drivers, ecology and pathogen evolutionEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
This document presents a mathematical model to eliminate malaria transmission by breaking the life cycle of Anopheles mosquitoes. The model introduces two natural enemies - copepods to prey on mosquito larvae and tadpoles to prey on pupae. Differential equations were derived to model the growth of each mosquito life stage from egg to adult when under attack by these predators. Stability analysis of the disease-free equilibrium was conducted using equilibrium points, Beltrami's conditions, and Diekmann's conditions. The results indicate that introducing copepods and tadpoles makes the disease-free equilibrium stable, meaning the mosquito life cycle would be broken and no adult mosquitoes emerge to transmit malaria.
Relations between pathogens, hosts and environmentEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
Malaria is caused by parasites transmitted through mosquito bites. It affects over 200 million people annually and causes over 1 million deaths. Biotechnology research is working to develop new treatments, such as vaccines and drugs targeting different stages of the parasite's lifecycle. Detection of malaria has also advanced through new diagnostic tests identifying parasite biomarkers using techniques like monoclonal antibodies and real-time PCR. While progress has been made, drug resistance remains a major challenge, and continued biotechnology research is needed to control and eliminate malaria worldwide.
This document describes a study examining options to control Lyme disease in Doctor's Park in Milwaukee County, Wisconsin. A simulation model was used to estimate tick populations based on mammal populations that ticks feed on. Simulations reduced populations of individual species and combinations of species. Results showed that reducing small rodent populations like mice and chipmunks by 50% combined with increasing red fox populations reduced infected ticks per hectare the most, to less than 1% of the baseline. Reducing nuisance species like raccoons increased infected ticks.
The Evolution of Viral Pathogens in Veterinary Medicine: Canine Parvovirus an...Kara Moloney
Viral pathogens like canine parvovirus (CPV) and canine influenza virus pose challenges for veterinary medicine due to their ability to rapidly evolve. CPV emerged in 1978 and has since evolved into multiple variants, including CPV-2a, CPV-2b, and CPV-2c. These variants differ in their viral capsid protein VP2, which affects host specificity. Canine influenza is an influenza A virus that crossed over from equines to canines in 2004. While not causing major outbreaks like CPV, it still poses a threat through potential evolution. Both viruses continue adapting transmissibility and host range through genetic mutations under selection pressure.
The study investigated the transmission of Salmonella enterica, Cronobacter sakazakii, Escherichia coli O157:H7, and Listeria monocytogenes from adult house flies to their eggs and first filial (F1) generation adults. The researchers fed adult house flies food contaminated with low, medium, and high levels of each pathogen. They found that all pathogens were present in samples of pooled house fly eggs. Transmission was highest when adults consumed medium bacterial loads. Cronobacter sakazakii was most likely to be transmitted to eggs. S. enterica and C. sakazakii were transmitted to F1 adults and more likely to be found on their surfaces than in their guts
2 ijreh mar-2018-1-evaluation of some insecticidesAI Publications
The present study was planned to test on certain chemical insecticides from different groups such as organophosphates, pyrethroids and Bioinsecticide. Among these compounds two were chemical insecticides (Propetamphos and Cypermethrin), while the third one is Bioinsecticide (Baciloid 5000: Bacillus thuringiensis) against Culex pipiens, the dominant mosquito species in Abha city. Taking LC50 values (concentration which to kill 50% of mosquito larvae) into consideration, mosquito larvae of CX. Pipes against Propetamphos was effective (LC50 0.0162 ppm) against the 3rd instar of the laboratory strain comparing with a field strain which was 0.0442 ppm. At LC90 level, data indicated that Propetamphos (LC90 0.8109 ppm) was effective insecticide against the 3rd instar larvae of laboratory strain, while against field strain gave (LC90 3.31 ppm). Similarly, the results clearly showed that Cypermethrin was also very effective insecticide (LC50 0.0132 ppm) against the adult females against laboratory strain, while against field strain Cypermethrin gave (LC50 0.1192 ppm). On the other hand, the residual activity of Bacillus thuringiensis var. israelensis reached from 4 to 20 days of concentrations ranged between 0.001 to 100 p.m. in case laboratory strain, while reaching between 6-23 days of concentrations ranged between 0.001 to 100 p.m. in case field strain. Mortality percent was also found between 11.7 to 96.8% of concentrations ranged between 0.001 to 100 p.m. against laboratory strain in the 1st week, whereas ranged between 0.0 to 70.8% in the 2nd week against the same concentrations finally ranged between 0.0 to 12.7% in the 3rd week. Hence, the field collected larvae of Culex pipens were more susceptible and have prolonged residual effect as compared to laboratory reared.
This study found ESBL-producing E. coli bacteria on house flies and blow flies caught at two poultry farms in the Netherlands. At a broiler farm, ESBL-producing E. coli was detected in a pool of blow flies and in fly isolates that matched types found in manure and rinse water at the farm. At a laying hen farm, all fly and manure isolates carried the same ESBL genotype. The results suggest that flies acquire ESBL-producing E. coli at poultry farms and could contribute to the dissemination of these bacteria into the community.
The Effect of Animal Agriculture Housing Conditions on the Emergence of the A...Carrie Ducote
This document discusses the housing conditions of commercial poultry and their role in the recent avian influenza outbreak. It argues that keeping large numbers of birds in crowded, stressful conditions allows viruses to easily spread and mutate, making them highly contagious and deadly. The document provides background on avian influenza, outlines the life of commercial poultry, and gives a timeline of the 2014-2015 outbreak in the US that impacted poultry in several states. It ultimately concludes that animal agriculture practices contribute to the emergence and spread of infectious diseases.
Prevalence and resistance of bacterial strains isolated from chicken beddings...IOSRJAVS
The main interest of researchers is focused on the microbiology of the industrial poultry beddings. In this study the microbiology and the microbial resistance of strains isolated from composite samples of poultry (gallus gallus domesticus) beddings originating from rural households has been investigated. In the area of Arta (Epirus, Greece) samples were collected from 300 rural households. These samples were classified regarding the following 4 criteria: (a) the size of the chicken flock, (b) the presence of different poultry species in the same household, (c) the presence of small ruminants in the same household and (d) differences in feeding practices. Results reveal that the microbiology of the beddings was mostly affected by the presence of small ruminants in the same household and the administration of concentrated feeds. Microbial resistance followed the same distribution pattern. The most resistant strains were isolated from samples originating from households breeding both poultry and small ruminants. Feeding with concentrated feeds was a determinant factor and probably the link between resistance and prevalence.
Antiviral Effects of Beta Lactoglobulin against Avian Influenza Virusijtsrd
Introduction The avian virus is an Influenza A virus that spread widely among human through direct or indirect contact with infected birds or poultry. But a totally new pandemic of avian virus those are becoming resistant to drugs by changing their genomes may be prevented by antiviral medicines and vaccines. Objective For this purpose ß lactoglobulin is esterified with various alcohols over different circumstances like acidity, protein intentness, water substance, time, temperature, etc. Methodology Methylated ß lactoglobulin provides antiviral activities against human flu infection subtype H3N2, subtype H1N1, and subtype H5N1. The impact of this study is viral HA Hemagglutinin action is repressed by the imposition of different convergences of MET BLG depending upon their distinctive concentration. Result A large number of positive charges on the MET BLG can disrupt the electrostatic intuitive inside hem agglutinin subunits that influences its soundness and movement, lessens its capacity to intertwine and restraints its contamination power. But HA is not the unique factor that decides the viral virulence and infectivity of the virus. Conclusion A different result shows that a higher incubation time increases the antiviral activity of MET BLG. Sadia Afrin | Rezwan Ahmed Mahedi | Mimona Akter "Antiviral Effects of Beta-Lactoglobulin against Avian Influenza Virus" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-1 , December 2020, URL: https://www.ijtsrd.com/papers/ijtsrd38098.pdf Paper URL : https://www.ijtsrd.com/biological-science/microbiology/38098/antiviral-effects-of-betalactoglobulin-against-avian-influenza-virus/sadia-afrin
Interval observer for uncertain time-varying SIR-SI model of vector-borne dis...FGV Brazil
The issue of state estimation is considered for an SIR-SI model describing a vector-borne disease such as dengue fever, with seasonal variations and uncertainties in the transmission rates. Assuming continuous measurement of the number of new infectives in the host population per unit time, a class of interval observers with estimate-dependent gain is constructed, and asymptotic error bounds are provided. The synthesis method is based on the search for a common linear Lyapunov function for monotone systems representing the evolution of the estimation errors.
Date: 2017
Authors:
Soledad Aronna, Maria
Bliman, Pierre-Alexandre
Ensuring successful introduction of Wolbachia in natural populations of Aedes...FGV Brazil
The control of the spread of dengue fever by introduction of the intracellular parasitic bacterium Wolbachia in populations of the vector Aedes aegypti, is presently one of the most promising tools for eliminating dengue, in the absence of an efficient vaccine. The success of this operation requires locally careful planning to determine the adequate number of individuals carrying the wolbachia parasite that need to be introduced into the natural population. The introduced mosquitoes are expected to eventually replace the Wolbachia-free population and guarantee permanent protection against the transmission of dengue to human. In this study, we propose and analyze a model describing the fundamental aspects of the competition between mosquitoes carrying Wolbachia and mosquitoes free of the parasite. We then use feedback control techniques to devise an introduction protocol which is proved to guarantee that the population converges to a stable equilibrium where the totality of mosquitoes carry Wolbachia.
Date: 2015-03-19
Authors:
Bliman, Pierre-Alexandre
Soledad Aronna, Maria
Coelho, Flávio Codeço
Silva, Moacyr da
Discovering novel pathways of cross-species pathogen transmissionEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
Culling of livestock has traditionally been used to control disease outbreaks but has several disadvantages. It negatively impacts biodiversity, genetic diversity of breeds, and small scale farmers. It is also emotionally difficult and expensive. Computer models could simulate alternative husbandry practices like organic agriculture and local food systems to examine their impact on disease spread and economic costs compared to current industrialized practices. This may help identify more sustainable approaches to disease control.
Il ruolo dell'infezione da VRS nell’origine e nella progressione dell’asma: r...MerqurioEditore_redazione
This document summarizes findings from a mouse model study on the role of respiratory syncytial virus (RSV) infection in asthma initiation and progression. The summary is:
1) Mouse models have provided insight into the pathophysiology of RSV-induced disease and the link between early RSV infection and later asthma.
2) Studies show that prior exposure to allergens increases RSV-induced airway hyperresponsiveness and inflammation in mice.
3) The timing of RSV infection relative to allergen exposure is important, with RSV enhancing allergic responses more when infection follows allergen exposure.
Capstone Paper- Stacy and Vitalia FINALStacy Jacobs
The document summarizes research on Aedes aegypti and Aedes albopictus mosquitoes as vectors of dengue transmission and prevention. It discusses the life cycle and morphological identification features of these mosquitoes. It also examines how Wolbachia bacteria can be used to inhibit dengue spread by inducing cytoplasmic incompatibility in mosquito eggs, reducing female lifespan, and causing proboscis deformities.
Simulation of an Intracellular Differential Equation Model of the Dynamics of...ijtsrd
We designed a simulation of an intracellular differential equation model of the dynamics of malaria with immune control and treatment which considered malaria parasites in the liver and blood. We considered transmission dynamics of malaria and the interaction between the infection in the liver and blood. The disease free equilibrium of our model was asymptotically stable when the basic reproduction number is less than one and unstable when it is greater than one. Numerical simulations show that if the immune response is strong with effective treatment, malaria infection will be cleared from an infectious human host. A treatment strategy using highly effective drugs against malaria parasites with strong immune response can reduce malaria progression and control the disease. Titus Ifeanyi Chinebu | Edmund Onwubiko Ezennorom | John U Okwor "Simulation of an Intracellular Differential Equation Model of the Dynamics of Malaria with Immune Control and Treatment" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-6 , October 2018, URL: http://www.ijtsrd.com/papers/ijtsrd18476.pdf
Combating cummunicable diseases at the farm - wildlife interfaceH. (Harry) Rozendaal
This document discusses the risks of communicable diseases spreading between domesticated animals and wildlife. It provides examples of diseases that have spread in this way, such as avian influenza between poultry and wild birds, bovine tuberculosis between cattle and wildlife like possums and deer, and African swine fever between domestic pigs and wild boar. The author argues that minimizing contact between domestic and wild animals, quickly controlling outbreaks in domestic populations, and avoiding disturbing, gathering or feeding wild animals can help curb the cycle of infection at the wildlife-domestic animal interface.
This document summarizes a doctoral thesis on the pharmaceutical and immunological challenges of fungal pathogens. The thesis explored the interactions between the pathogenic fungus Candida albicans and human immune cells like neutrophils and mast cells. It developed a high-throughput screening assay to identify small molecules that block the yeast-to-hypha transition in C. albicans, which is important for its virulence. The screening revealed several FDA-approved drugs with previously unknown antifungal activity. The thesis provides new insights into antifungal defenses and tools to discover more effective antifungal therapies.
This document discusses how human activity like deforestation, wildlife trafficking, and habitat destruction are increasing contact between humans and animal species, allowing viruses to jump between species and potentially cause pandemics. Experts warn that if this destruction of nature continues, even deadlier pandemics will emerge more frequently in the future. Implementing measures to reduce human interaction with wildlife through investments in monitoring wildlife trade and preventing deforestation could help avoid future pandemics at a relatively low cost compared to the massive economic impacts of pandemics like COVID-19. Urgent changes are needed in human relationships with nature to protect humanity from pandemics threatening its existence.
Bluetongue virus is an arbovirus spread to cattle by Culicoides biting midges. It can cause hemorrhagic fever and abortion in cattle. While often asymptomatic, it impacts economics through reduced cattle productivity. There are 26 serotypes with different levels of pathogenicity. The virus is not contagious between cattle but is infectious when spread by midge vectors. Vaccines provide protection against homologous serotypes but multiple vaccines may be needed in endemic areas with several circulating strains. Control relies on limiting animal movement and effective vector control combined with vaccination.
This document summarizes several novel approaches to combat mosquito-borne diseases. It discusses 1) a project in Australia that introduces Wolbachia bacteria into mosquitoes to block dengue virus transmission, 2) a technique used in the Cayman Islands that releases genetically modified sterile male mosquitoes to suppress wild populations, and 3) an experiment creating malaria-resistant mosquitoes by shortening their lifespan and blocking Plasmodium falciparum infection. While these techniques show promise, challenges remain regarding public opposition, the risk of other diseases persisting, and determining the optimal methods.
Incidence of Methicillin-Resistant Staphylococcus aureus (MRSA) In a Small Po...IOSR Journals
Three key points:
1) Nasal swabs from 25 symptomatic poultry attendants and 95% of cloacal swabs from chickens with diarrhea yielded Methicillin-resistant Staphylococcus aureus (MRSA), indicating a high prevalence of MRSA in both the attendants and chickens.
2) Only 5 asymptomatic attendants carried Methicillin-sensitive Staphylococcus aureus (MSSA), suggesting MRSA was responsible for symptoms in attendants.
3) The high incidence of MRSA in chickens (95%) and attendants (83.3%) suggests cross-infection was occurring from chickens to attendants through physical contact and exposure to chicken feces.
The document describes the development of a reverse line blot (RLB) hybridization kit that can simultaneously detect four genera of common tick-borne pathogens - Anaplasma, Ehrlichia, Babesia and Theileria. This provides a sensitive and cost-effective diagnostic tool that facilitates the study of tick-borne diseases. The RLB technique involves PCR amplification of the pathogens, followed by hybridization of the products on a membrane containing genus-specific probes. This allows for simultaneous identification of any of the pathogens present in one sample. The kit will support improved diagnosis and epidemiological research on these important diseases affecting both animals and humans.
This study analyzed 846 E. coli isolates from 113 surface water samples and 313 E. coli isolates from 33 wastewater samples in the Netherlands. The researchers found that 26% of surface water E. coli isolates and much higher percentages of wastewater E. coli isolates (31-76%) were resistant to at least one of 8 classes of antimicrobials tested. Multidrug resistance was found in 11% of surface water isolates and significantly higher percentages (19-62%) of wastewater isolates. Median concentrations of multidrug resistant E. coli were highest in wastewater from health care institutions and lowest in surface water. The study indicates that municipal wastewater contributes significantly to the occurrence of antimicrobial resistant E
2 ijreh mar-2018-1-evaluation of some insecticidesAI Publications
The present study was planned to test on certain chemical insecticides from different groups such as organophosphates, pyrethroids and Bioinsecticide. Among these compounds two were chemical insecticides (Propetamphos and Cypermethrin), while the third one is Bioinsecticide (Baciloid 5000: Bacillus thuringiensis) against Culex pipiens, the dominant mosquito species in Abha city. Taking LC50 values (concentration which to kill 50% of mosquito larvae) into consideration, mosquito larvae of CX. Pipes against Propetamphos was effective (LC50 0.0162 ppm) against the 3rd instar of the laboratory strain comparing with a field strain which was 0.0442 ppm. At LC90 level, data indicated that Propetamphos (LC90 0.8109 ppm) was effective insecticide against the 3rd instar larvae of laboratory strain, while against field strain gave (LC90 3.31 ppm). Similarly, the results clearly showed that Cypermethrin was also very effective insecticide (LC50 0.0132 ppm) against the adult females against laboratory strain, while against field strain Cypermethrin gave (LC50 0.1192 ppm). On the other hand, the residual activity of Bacillus thuringiensis var. israelensis reached from 4 to 20 days of concentrations ranged between 0.001 to 100 p.m. in case laboratory strain, while reaching between 6-23 days of concentrations ranged between 0.001 to 100 p.m. in case field strain. Mortality percent was also found between 11.7 to 96.8% of concentrations ranged between 0.001 to 100 p.m. against laboratory strain in the 1st week, whereas ranged between 0.0 to 70.8% in the 2nd week against the same concentrations finally ranged between 0.0 to 12.7% in the 3rd week. Hence, the field collected larvae of Culex pipens were more susceptible and have prolonged residual effect as compared to laboratory reared.
This study found ESBL-producing E. coli bacteria on house flies and blow flies caught at two poultry farms in the Netherlands. At a broiler farm, ESBL-producing E. coli was detected in a pool of blow flies and in fly isolates that matched types found in manure and rinse water at the farm. At a laying hen farm, all fly and manure isolates carried the same ESBL genotype. The results suggest that flies acquire ESBL-producing E. coli at poultry farms and could contribute to the dissemination of these bacteria into the community.
The Effect of Animal Agriculture Housing Conditions on the Emergence of the A...Carrie Ducote
This document discusses the housing conditions of commercial poultry and their role in the recent avian influenza outbreak. It argues that keeping large numbers of birds in crowded, stressful conditions allows viruses to easily spread and mutate, making them highly contagious and deadly. The document provides background on avian influenza, outlines the life of commercial poultry, and gives a timeline of the 2014-2015 outbreak in the US that impacted poultry in several states. It ultimately concludes that animal agriculture practices contribute to the emergence and spread of infectious diseases.
Prevalence and resistance of bacterial strains isolated from chicken beddings...IOSRJAVS
The main interest of researchers is focused on the microbiology of the industrial poultry beddings. In this study the microbiology and the microbial resistance of strains isolated from composite samples of poultry (gallus gallus domesticus) beddings originating from rural households has been investigated. In the area of Arta (Epirus, Greece) samples were collected from 300 rural households. These samples were classified regarding the following 4 criteria: (a) the size of the chicken flock, (b) the presence of different poultry species in the same household, (c) the presence of small ruminants in the same household and (d) differences in feeding practices. Results reveal that the microbiology of the beddings was mostly affected by the presence of small ruminants in the same household and the administration of concentrated feeds. Microbial resistance followed the same distribution pattern. The most resistant strains were isolated from samples originating from households breeding both poultry and small ruminants. Feeding with concentrated feeds was a determinant factor and probably the link between resistance and prevalence.
Antiviral Effects of Beta Lactoglobulin against Avian Influenza Virusijtsrd
Introduction The avian virus is an Influenza A virus that spread widely among human through direct or indirect contact with infected birds or poultry. But a totally new pandemic of avian virus those are becoming resistant to drugs by changing their genomes may be prevented by antiviral medicines and vaccines. Objective For this purpose ß lactoglobulin is esterified with various alcohols over different circumstances like acidity, protein intentness, water substance, time, temperature, etc. Methodology Methylated ß lactoglobulin provides antiviral activities against human flu infection subtype H3N2, subtype H1N1, and subtype H5N1. The impact of this study is viral HA Hemagglutinin action is repressed by the imposition of different convergences of MET BLG depending upon their distinctive concentration. Result A large number of positive charges on the MET BLG can disrupt the electrostatic intuitive inside hem agglutinin subunits that influences its soundness and movement, lessens its capacity to intertwine and restraints its contamination power. But HA is not the unique factor that decides the viral virulence and infectivity of the virus. Conclusion A different result shows that a higher incubation time increases the antiviral activity of MET BLG. Sadia Afrin | Rezwan Ahmed Mahedi | Mimona Akter "Antiviral Effects of Beta-Lactoglobulin against Avian Influenza Virus" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-1 , December 2020, URL: https://www.ijtsrd.com/papers/ijtsrd38098.pdf Paper URL : https://www.ijtsrd.com/biological-science/microbiology/38098/antiviral-effects-of-betalactoglobulin-against-avian-influenza-virus/sadia-afrin
Interval observer for uncertain time-varying SIR-SI model of vector-borne dis...FGV Brazil
The issue of state estimation is considered for an SIR-SI model describing a vector-borne disease such as dengue fever, with seasonal variations and uncertainties in the transmission rates. Assuming continuous measurement of the number of new infectives in the host population per unit time, a class of interval observers with estimate-dependent gain is constructed, and asymptotic error bounds are provided. The synthesis method is based on the search for a common linear Lyapunov function for monotone systems representing the evolution of the estimation errors.
Date: 2017
Authors:
Soledad Aronna, Maria
Bliman, Pierre-Alexandre
Ensuring successful introduction of Wolbachia in natural populations of Aedes...FGV Brazil
The control of the spread of dengue fever by introduction of the intracellular parasitic bacterium Wolbachia in populations of the vector Aedes aegypti, is presently one of the most promising tools for eliminating dengue, in the absence of an efficient vaccine. The success of this operation requires locally careful planning to determine the adequate number of individuals carrying the wolbachia parasite that need to be introduced into the natural population. The introduced mosquitoes are expected to eventually replace the Wolbachia-free population and guarantee permanent protection against the transmission of dengue to human. In this study, we propose and analyze a model describing the fundamental aspects of the competition between mosquitoes carrying Wolbachia and mosquitoes free of the parasite. We then use feedback control techniques to devise an introduction protocol which is proved to guarantee that the population converges to a stable equilibrium where the totality of mosquitoes carry Wolbachia.
Date: 2015-03-19
Authors:
Bliman, Pierre-Alexandre
Soledad Aronna, Maria
Coelho, Flávio Codeço
Silva, Moacyr da
Discovering novel pathways of cross-species pathogen transmissionEFSA EU
Presentation of the EFSA's second scientific conference, held on 14-16 October 2015 in Milan, Italy.
DRIVERS FOR EMERGING ISSUES IN ANIMAL AND PLANT HEALTH
Culling of livestock has traditionally been used to control disease outbreaks but has several disadvantages. It negatively impacts biodiversity, genetic diversity of breeds, and small scale farmers. It is also emotionally difficult and expensive. Computer models could simulate alternative husbandry practices like organic agriculture and local food systems to examine their impact on disease spread and economic costs compared to current industrialized practices. This may help identify more sustainable approaches to disease control.
Il ruolo dell'infezione da VRS nell’origine e nella progressione dell’asma: r...MerqurioEditore_redazione
This document summarizes findings from a mouse model study on the role of respiratory syncytial virus (RSV) infection in asthma initiation and progression. The summary is:
1) Mouse models have provided insight into the pathophysiology of RSV-induced disease and the link between early RSV infection and later asthma.
2) Studies show that prior exposure to allergens increases RSV-induced airway hyperresponsiveness and inflammation in mice.
3) The timing of RSV infection relative to allergen exposure is important, with RSV enhancing allergic responses more when infection follows allergen exposure.
Capstone Paper- Stacy and Vitalia FINALStacy Jacobs
The document summarizes research on Aedes aegypti and Aedes albopictus mosquitoes as vectors of dengue transmission and prevention. It discusses the life cycle and morphological identification features of these mosquitoes. It also examines how Wolbachia bacteria can be used to inhibit dengue spread by inducing cytoplasmic incompatibility in mosquito eggs, reducing female lifespan, and causing proboscis deformities.
Simulation of an Intracellular Differential Equation Model of the Dynamics of...ijtsrd
We designed a simulation of an intracellular differential equation model of the dynamics of malaria with immune control and treatment which considered malaria parasites in the liver and blood. We considered transmission dynamics of malaria and the interaction between the infection in the liver and blood. The disease free equilibrium of our model was asymptotically stable when the basic reproduction number is less than one and unstable when it is greater than one. Numerical simulations show that if the immune response is strong with effective treatment, malaria infection will be cleared from an infectious human host. A treatment strategy using highly effective drugs against malaria parasites with strong immune response can reduce malaria progression and control the disease. Titus Ifeanyi Chinebu | Edmund Onwubiko Ezennorom | John U Okwor "Simulation of an Intracellular Differential Equation Model of the Dynamics of Malaria with Immune Control and Treatment" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-6 , October 2018, URL: http://www.ijtsrd.com/papers/ijtsrd18476.pdf
Combating cummunicable diseases at the farm - wildlife interfaceH. (Harry) Rozendaal
This document discusses the risks of communicable diseases spreading between domesticated animals and wildlife. It provides examples of diseases that have spread in this way, such as avian influenza between poultry and wild birds, bovine tuberculosis between cattle and wildlife like possums and deer, and African swine fever between domestic pigs and wild boar. The author argues that minimizing contact between domestic and wild animals, quickly controlling outbreaks in domestic populations, and avoiding disturbing, gathering or feeding wild animals can help curb the cycle of infection at the wildlife-domestic animal interface.
This document summarizes a doctoral thesis on the pharmaceutical and immunological challenges of fungal pathogens. The thesis explored the interactions between the pathogenic fungus Candida albicans and human immune cells like neutrophils and mast cells. It developed a high-throughput screening assay to identify small molecules that block the yeast-to-hypha transition in C. albicans, which is important for its virulence. The screening revealed several FDA-approved drugs with previously unknown antifungal activity. The thesis provides new insights into antifungal defenses and tools to discover more effective antifungal therapies.
This document discusses how human activity like deforestation, wildlife trafficking, and habitat destruction are increasing contact between humans and animal species, allowing viruses to jump between species and potentially cause pandemics. Experts warn that if this destruction of nature continues, even deadlier pandemics will emerge more frequently in the future. Implementing measures to reduce human interaction with wildlife through investments in monitoring wildlife trade and preventing deforestation could help avoid future pandemics at a relatively low cost compared to the massive economic impacts of pandemics like COVID-19. Urgent changes are needed in human relationships with nature to protect humanity from pandemics threatening its existence.
Bluetongue virus is an arbovirus spread to cattle by Culicoides biting midges. It can cause hemorrhagic fever and abortion in cattle. While often asymptomatic, it impacts economics through reduced cattle productivity. There are 26 serotypes with different levels of pathogenicity. The virus is not contagious between cattle but is infectious when spread by midge vectors. Vaccines provide protection against homologous serotypes but multiple vaccines may be needed in endemic areas with several circulating strains. Control relies on limiting animal movement and effective vector control combined with vaccination.
This document summarizes several novel approaches to combat mosquito-borne diseases. It discusses 1) a project in Australia that introduces Wolbachia bacteria into mosquitoes to block dengue virus transmission, 2) a technique used in the Cayman Islands that releases genetically modified sterile male mosquitoes to suppress wild populations, and 3) an experiment creating malaria-resistant mosquitoes by shortening their lifespan and blocking Plasmodium falciparum infection. While these techniques show promise, challenges remain regarding public opposition, the risk of other diseases persisting, and determining the optimal methods.
Incidence of Methicillin-Resistant Staphylococcus aureus (MRSA) In a Small Po...IOSR Journals
Three key points:
1) Nasal swabs from 25 symptomatic poultry attendants and 95% of cloacal swabs from chickens with diarrhea yielded Methicillin-resistant Staphylococcus aureus (MRSA), indicating a high prevalence of MRSA in both the attendants and chickens.
2) Only 5 asymptomatic attendants carried Methicillin-sensitive Staphylococcus aureus (MSSA), suggesting MRSA was responsible for symptoms in attendants.
3) The high incidence of MRSA in chickens (95%) and attendants (83.3%) suggests cross-infection was occurring from chickens to attendants through physical contact and exposure to chicken feces.
The document describes the development of a reverse line blot (RLB) hybridization kit that can simultaneously detect four genera of common tick-borne pathogens - Anaplasma, Ehrlichia, Babesia and Theileria. This provides a sensitive and cost-effective diagnostic tool that facilitates the study of tick-borne diseases. The RLB technique involves PCR amplification of the pathogens, followed by hybridization of the products on a membrane containing genus-specific probes. This allows for simultaneous identification of any of the pathogens present in one sample. The kit will support improved diagnosis and epidemiological research on these important diseases affecting both animals and humans.
This study analyzed 846 E. coli isolates from 113 surface water samples and 313 E. coli isolates from 33 wastewater samples in the Netherlands. The researchers found that 26% of surface water E. coli isolates and much higher percentages of wastewater E. coli isolates (31-76%) were resistant to at least one of 8 classes of antimicrobials tested. Multidrug resistance was found in 11% of surface water isolates and significantly higher percentages (19-62%) of wastewater isolates. Median concentrations of multidrug resistant E. coli were highest in wastewater from health care institutions and lowest in surface water. The study indicates that municipal wastewater contributes significantly to the occurrence of antimicrobial resistant E
A single-reaction quadruplex qPCR assay was developed that can rapidly detect and differentiate Burkholderia mallei and Burkholderia pseudomallei. The assay uses three signature sequences - a multicopy transposase sequence common to both species for sensitive detection, and two unique sequences for species differentiation. It also incorporates an internal control for DNA extraction and amplification using Bacillus thuringiensis. The assay enables detection of less than 1 genome equivalent and differentiation of B. mallei and B. pseudomallei with high sensitivity and reliability for diagnostic and surveillance purposes.
Nucleic acid hybridization can be used to identify particular DNA sequences using a nucleic acid probe. The technique takes advantage of DNA's property of complementary base pairing - if DNA is separated into single strands, the complementary strands will reform into double helices when conditions are right. A nucleic acid probe is a short, radioactively labelled single-stranded DNA or RNA molecule that binds to complementary nucleic acid sequences, allowing them to be identified. Genetic mapping uses genetic markers and recombination frequency during meiosis to locate genes on chromosomes and establish the relative distances between genes.
This document discusses various methods for labeling nucleic acid probes used in hybridization experiments. It describes five basic methods: nick translation, primer extension, methods using RNA polymerase, end labeling, and direct labeling. Nick translation involves making cuts in double-stranded DNA and using DNA polymerase to replace one strand with a radioactive or biotin-labeled strand. Primer extension involves extending a primer that is complementary to the probe sequence using DNA polymerase and labeled nucleotides. RNA polymerase methods use the enzyme to incorporate labeled nucleotides during transcription. End labeling adds a label to the 3' or 5' end of nucleic acids. The document also discusses factors to consider when choosing a label such as radioactive versus non-radioactive options.
Molecular probes are small DNA or RNA segments that are used to detect complementary nucleic acid sequences in samples. There are several types of probes including genomic DNA probes, cDNA probes, synthetic oligonucleotides, and RNA probes. Probes are typically labeled with radioactive isotopes or non-radioactive labels like fluorophores or biotin to allow for detection after hybridization with target sequences. Molecular probes have many applications including genetic mapping, DNA fingerprinting, and diagnosis of diseases.
This document discusses molecular hybridization of nucleic acids. It begins by defining molecular hybridization as the process where two complementary single-stranded nucleic acid molecules form a double-stranded structure. It then provides details on the principles of nucleic acid hybridization, including how probes are used to bind to target sequences. Application of these techniques are also summarized, including Southern blot hybridization where target DNA is detected after gel electrophoresis and transfer to a membrane.
This document discusses nucleotide probes, which are single-stranded DNA or RNA fragments that are labeled and complementary to a target DNA sequence. Probes can range in size from 15 base pairs to several hundred kilobases. They are used to identify a specific DNA fragment through base pairing. Probes must be labeled to be detected, typically through radioactive labeling or fluorescent tags. Labeling can occur on the end of the probe or through polymerase-based incorporation of multiple labeled nucleotides during DNA synthesis. Probes have various uses, including searching DNA libraries and diagnosing genetic disorders through techniques like Southern and Northern blotting.
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
Plague is caused by the bacterium Yersinia pestis and is primarily a disease of rodents and their fleas. It can occur in various forms including endemic, epidemic, sporadic, pneumonic and bubonic. While historically a major epidemic disease, plague still causes occasional outbreaks in parts of Africa, Asia and the Americas. Transmission is usually from infected rodents to humans via flea bites. Diagnosis involves lab tests of samples from patients. Treatment involves antibiotics like streptomycin. Control relies on early detection, vaccination, flea and rodent control through insecticides and improved sanitation.
According to a recent study conducted by the US Department of Agriculture's Animal and Plant Health Inspection Service, it has been discovered that the virus responsible for Covid-19 was transmitted to wild white-tailed deer in the United States more than 100 times during late 2021 and early 2022. This finding indicates that the infection spread extensively within the deer population, and there are even instances where researchers suspect that humans contracted the virus from deer.
Soil-transmitted helminth infections (STH) and schistosomiasis constitute major public health challenges among school‐age children in sub-Saharan Africa. Chemotherapy with the Benzimidazole chemical family is one of the most effective strategies to lower the rates of morbidity and mortality. But now a day anthelmintic resistance in the treatment and control of human helminthes has been reported in different areas in Ethiopia. The objective of this study, therefore, is to assess the efficacy of albendazole (400 mg, manufactured by Khandeiwal Laboratories Pvt. Ltd) currently in use against soil-transmitted helminth infections among school children in many areas of Ethiopia. A total of 180 elementary school children were chosen using random sampling technique. Each student was instructed to submit fresh stool specimen. Formal ether concentration technique and Kato-Katz method were done at the study sites and Aksum University, laboratory of Department of Biology and Biotechnology. Among the total study children, 170 submitted fresh stool samples giving a response rate of 96.77%. The overall prevalence of helminth infection was 66.7 % (Adiet), 67.9% (Adwa) and 51.7% (Aksum). In all the study sites albendazole was effective against most soil-transmitted helminthes, with cure rate > 85%, and egg reduction rate >90%. However, it was less effective against Trichuris trichiura with cure rate 58.5% and 57.9% at Adiet and Adwa, respectively. Therefore, due attention should be given with regard to treating helminth positive individuals together with intense environmental sanitation to curb the burden of helminth infection and alternative chemotherapy against Trichuris trichiura should be supplied to the study areas.
This document provides information about a proposed study on assessing the effectiveness of a structured teaching program on knowledge about prevention and control of bird flu among poultry farm workers. It includes background information on bird flu, the need for the study based on gaps in knowledge and outbreaks globally and in India, and a review of previous studies conducted on knowledge and practices of poultry workers regarding avian influenza. The study aims to educate poultry workers and help control and manage bird flu outbreaks.
this presentation put insights on the most important pivots of the Crimean-Cong Hemorrhagic Fever in Iraq and the World and was a part of institutional efforts represented by University of Misan/Iraq as step of many steps to educate community to this dangerous zoonotic disease.
Genomic epidemiology of Campylobacter jejuni associated with asymptomatic pae...Ben Pascoe
The document summarizes research on Campylobacter jejuni associated with asymptomatic paediatric infection in the Peruvian Amazon. It finds that isolates from Peruvian children have a local gene pool and genotypes rarely seen globally. Lineages associated with asymptomatic infection are proliferating in the region. Though globally circulating strains are present, the regional accessory genome content differs. Poultry is identified as the predominant infection source for children in the Peruvian Amazon. Further sampling is needed to better understand regional differences and reservoirs.
The document discusses chicken (poultry) as an animal model for studying human diseases like coronaviruses. It notes that the first coronavirus discovered was the avian infectious bronchitis virus (IBV) in chickens in the 1930s. Drawing from decades of experience with IBV, the poultry industry can provide insights into zoonotic coronaviruses like SARS-CoV-2 that cause COVID-19. The document outlines similarities between IBV and human coronaviruses in terms of structure, genome and replication mechanisms.
Prevalence of Coccidiosis in Back Yard Chicken in and Around DebereTabere Tow...CrimsonpublishersCJMI
Prevalence of Coccidiosis in Back Yard Chicken in and Around DebereTabere Town, South Gondar Zone, Amhara Regional State, Ethiopia by Temesigen W Molla in Cohesive Journal of Microbiology & Infectious Disease
The document discusses Brucellosis, also known as Mediterranean fever. It is caused by Brucella bacteria, which are small, aerobic, Gram-negative coccobacilli. Brucellosis is transmitted primarily through contact with infected animals or consumption of unpasteurized dairy. It affects people occupationally exposed to livestock. Prevalence is highest in Mediterranean countries and the Middle East. In Egypt, a study found prevalence rates in cattle, buffalo, sheep and goats were highest in Benisuef governorate. All isolates in Egypt were identified as B. melitensis, which is the main cause of brucellosis in animals and humans in many countries.
Zoonotic infections are diseases that can spread from animals to humans. Over 60% of infectious diseases in humans are zoonotic. Transmission can occur through direct contact with infected animals, indirect contact, vectors like ticks and mosquitoes, or contaminated food. Common zoonotic diseases include anthrax, bovine tuberculosis, salmonellosis, E. coli, rabies, avian influenza, and prion diseases. Bacteria, viruses, parasites, fungi, and prions can all cause zoonotic diseases. Proper hygiene and food handling can help prevent transmission of zoonotic infections.
This presentation provides an overview of brucellosis, a bacterial disease caused by brucella organisms. It affects livestock such as cattle, goats, and sheep, and can be transmitted to humans. Symptoms in humans include fever, fatigue, joint pain, and abortion in pregnant women. While symptoms in animals include fever and abortion late in pregnancy. The disease is transmitted through contact with infected tissues/fluids from animals. Diagnosis involves culture and serological tests, while treatment consists of a combination of doxycycline and rifampin antibiotics for 6-8 weeks. Control relies on vaccination of animals and testing/culling of infected livestock.
The Role of Live Animal Markets in the US and Abroad in the Spread of Zoonoti...JosephGiambrone5
Live animal markets have contributed to the spread of zoonotic diseases like avian influenza and coronaviruses. In Southeast Asia, these markets often mix domestic and wild species in unsanitary conditions, allowing viruses to jump between animal hosts and potentially to humans. The first cases of SARS, MERS, and COVID-19 have all been linked to exposure at live animal markets in China, where bats and other wild animals infected domestic livestock. By contrast, live animal markets in the US have strict controls to prevent the introduction of exotic species and do not associate with disease emergence, as animals come from registered sources and are of single species. Uncontrolled live animal markets will continue enabling zoonotic viruses to spillover to humans
Alexander Gold - CAEV Literature Review for IndustryAlexander Gold
Caprine Arthritis Encephalitis Virus (CAEV) is a lentivirus that infects goats and causes arthritis, mastitis, and encephalitis. It is transmitted from mother goats to kids through colostrum and milk. While infection can also occur in utero or through contact, milk-borne transmission is the primary route. The virus infects white blood cells and travels to joints, mammary glands, and brain tissue, causing inflammation and disease. Diagnosis is through ELISA antibody tests and PCR DNA detection. There is no treatment, so control relies on identification and separation of infected animals.
This study investigated outbreaks of bovine viral diarrhea virus (BVDV), bovine herpesvirus 1 (BHV-1), and parainfluenza 3 virus (PI-3V) in three cattle herds in Egypt in 2000. In the first herd, BVDV alone caused calf disease and death. In the second herd, BVDV and PI-3V were found to jointly cause calf illness. In the third herd, BVDV, BHV-1, and PI-3V were all present and jointly caused calf disease characterized by enteritis and respiratory signs. Post-mortem examination revealed lesions in the gastrointestinal tract and lymphoreticular organs. Virological analysis identified the causal agents
This study investigated outbreaks of bovine viral diarrhea virus (BVDV), bovine herpesvirus 1 (BHV-1), and parainfluenza 3 virus (PI-3V) in three cattle herds in Egypt in 2000. In the first herd, BVDV alone caused calf disease and death. In the second herd, BVDV and PI-3V were found to jointly cause calf illness. In the third herd, BVDV, BHV-1, and PI-3V were all present and jointly caused calf disease characterized by enteritis and respiratory signs. Post-mortem examination revealed lesions in the gastrointestinal tract and lymphoreticular tissues. Immunohistochemistry identified the viral antigens in
Bacterial Orchitis and Epididymo-orchitis in Broiler BreedersRafael Monleon
A unilateral case of orchitis in a male broiler breeder was caused by Staphylococcus aureus, while a bilateral case of epididymo-orchitis in another male broiler breeder was caused by Escherichia coli. Microscopic examination found heterophilic interstitial-intratubular orchitis and epididymitis in both cases, with intralesional bacterial colonies. The infections were believed to have occurred via the ascending route in both cases. This report describes two cases of bacterial orchitis/epididymo-orchitis in broiler breeders and identifies novel causes.
Congo fever is a viral disease transmitted by ticks that infects both wild and domestic animals. Humans can contract the disease through tick bites or contact with infected animal blood and tissues. The virus is found worldwide but is most common in Africa, Asia, and Europe. It has an incubation period of 5-6 days and symptoms are often severe, resulting in death in 10-40% of cases. There is no vaccine currently available for humans. Treatment aims to manage symptoms, and the antiviral drug ribavirin may provide some benefit. Prevention involves avoiding tick bites and contact with infected animal blood and bodily fluids.
Analysis of ectoparasites and gastrointestinal parasites of chickens in moder...Innspub Net
A study was carried out in the commune of Korhogo to assess gastrointestinal parasites and ectoparasites in modern poultry farms. To achieve this, 214 droppings samples, including 129 broilers and 85 laying hens from 40 broiler farms and 12 laying chicken farms were collected and analyzed using the flotation method. The results highlighted two (2) species of mallophagous lice namely Menopon gallinae (50%) and Menacanthus stramineus (33%) and a species of bug namely Cimex lectularius (17%) for ectoparasites. As for the gastro-parasites, two (2) species and four (4) genera namely Trichostrongylus tenuis (17%), Syngamus trachea (19%); Heterakis sp (10%), Ascaridia sp (17%), Raillietina sp (8%) and Eimeria sp (29%) have been identified. Coccidiosis (Eimeria) was the most important pathology in broiler farms with 67% and less important in laying hens (33%). Helminth eggs have been observed more in laying hens. Ultimately laying hens are more infested than broilers.
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.
This document summarizes a study investigating the prevalence of ESBL-producing E. coli bacteria in four Dutch recreational waters and the potential role of nearby wastewater treatment plants (WWTPs) as contamination sources. Samples were taken from recreational waters, WWTP effluents, surface waters upstream and downstream of WWTP discharge points, and additional surface waters not influenced by the WWTPs. ESBL-producing E. coli were detected in all recreational waters and 62% of samples, with concentrations averaging 1.3 CFU/100ml. Isolates with identical genetic characteristics were found in WWTP effluents and surface waters, including occasionally in recreational waters, indicating WWTPs contribute to their presence. However,
This document discusses PCR-based assays for detecting Bacillus anthracis. It begins with an introduction to B. anthracis and the challenges in detecting it due to its similarity to other Bacillus species. It then describes a literature review and in silico analysis of over 300 published PCR primer/probe sequences targeting B. anthracis. Only 4 sequences were found to be 100% specific for B. anthracis based on comparisons to 134 Bacillus genome sequences. An inter-laboratory trial was then conducted among 5 European laboratories to evaluate 6 assays using 90 Bacillus strains. Three assays targeting the lambdaBa03 prophage region performed well without false positives or negatives.
This document summarizes work conducted in Task 5.1 of the EU AniBioThreat project to develop a minimum detection standard for Bacillus anthracis, the bacterium that causes anthrax. Methods for sampling, sample preparation, PCR detection, isolate characterization including whole genome sequencing and a metagenomics approach were evaluated. An inter-laboratory trial of 6 PCR assays showed some published assays had poor selectivity. Collaboration between partners improved diagnostic capabilities and knowledge sharing. The work contributes toward internationally recognized and validated standards for fast and accurate B. anthracis diagnosis in disease investigations and surveillance.
This document describes the development of a multiplex bead-based suspension array assay using Luminex technology to simultaneously genotype 13 phylogenetically informative single nucleotide polymorphisms (SNPs) in Bacillus anthracis. The assay is based on a modified Multiplex Oligonucleotide Ligation-PCR (MOL-PCR) method using dual-priming oligonucleotides for allele-specific probes to reduce cross-reactivity. The 13-plex assay was validated on 73 B. anthracis strains, demonstrating unambiguous SNP calls and lineage identification. An assay limit of detection of 2 ng genomic DNA was determined. The reproducibility and robustness of the method was confirmed in a small-scale proficiency test between four laboratories
This document describes a multicenter collaborative trial that validated two real-time PCR assays (GeneDisc arrays GD1 and GD2) for detecting Clostridium botulinum types C, D, C-D and D-C. The trial involved eight European laboratories testing the GeneDisc arrays on DNA from 33 C. botulinum isolates and 48 clinical samples. Results showed 99.4-100% concordance between laboratories. The assays demonstrated high reproducibility with low variability (1.1-7.1%). Given the high level of agreement, the GeneDisc PCR arrays were determined to be robust and suitable tools for rapid detection of C. botulinum types C, D and their mosaic variants. This was the first
This study found that rat tissues from farms in the Netherlands tested positive for the pla gene, which is a marker for Yersinia pestis. The pla gene sequences from rats were nearly identical to Y. pestis pla but further analysis identified adjacent sequences similar to bacterial replication genes. Attempts to culture or detect other Y. pestis markers from rat tissues were unsuccessful. The findings suggest there are unknown bacteria in rats that contain a pla homolog, which could produce false positive results in Y. pestis detection assays that only target the pla gene. Methods to confirm the presence of Y. pestis should include additional gene targets.
The document describes the development of two suspension microarray assays using different chemistries to detect four biothreat pathogens - Bacillus anthracis, Yersinia pestis, Francisella tularensis, and Coxiella burnetii. Sixteen DNA signatures from the pathogens were amplified using multiplex asymmetric PCR and detected using either direct hybridization (DH) or target-specific primer extension followed by universal hybridization (TSPE-UH). The specificity and sensitivity of both assays were evaluated and compared. The TSPE-UH assay showed lower background signals and was more specific while the DH assay had simpler procedures but lower signal-to-noise ratios. Both assays could detect pathogen DNA from mixed samples and
This document describes a European ring trial study to evaluate a real-time PCR assay for detection and typing of botulinum neurotoxin-producing Clostridia types A, B, E and F in food, feed and environmental samples. A primary evaluation of the real-time PCR method showed 100% accuracy, sensitivity, specificity and selectivity compared to the reference cultural method and mouse bioassay. A ring trial conducted at four European laboratories using 47 strains and 30 clinical and food samples linked to botulism cases showed 95.7% concordance among laboratories. The reproducibility generated a relative standard deviation of 2.18-13.61%. Given the high level of agreement between laboratories, this real-time PCR method is suitable
This document describes the development of a multiplex real-time PCR assay that can identify and differentiate B. anthracis from closely related Bacillus species as well as differentiate virulence types of B. anthracis. The assay was designed to target specific markers on the B. anthracis chromosome and plasmids pXO1 and pXO2. It also includes an internal control targeting the B. thuringiensis chromosome. The primers and probes were tested on a panel of B. anthracis strains and shown to correctly identify strains. The assay was also tested in laboratories in three different countries using different real-time PCR instruments. The assay provides a method to simultaneously identify B. anthracis,
The document describes the development of multiplex qPCR assays that can rapidly and reliably detect Bacillus anthracis, Francisella tularensis, and Yersinia pestis. The assays target pathogen-specific DNA sequences and include an internal control (B. thuringiensis cry1 gene) to control for DNA extraction and amplification. Validation showed the assays can simultaneously detect 3 pathogen targets with high sensitivity and specificity, and that inclusion of the internal control reduces the risk of false negatives. The assays provide a useful tool for the detection of these high-risk pathogens.
1) Researchers developed a multiplex real-time PCR protocol to specifically detect Bacillus anthracis and differentiate it from closely related Bacillus cereus strains.
2) The protocol simultaneously detects B. anthracis' chromosome and two plasmids (pXO1 and pXO2) as well as an internal control.
3) Evaluation across multiple institutes and PCR platforms showed the protocol generated consistent results, providing a reliable screening method for B. anthracis.
This document describes the development and application of a reverse transcription PCR (RT-PCR) assay for genotyping noroviruses (NoV) based on the major capsid protein VP1. The authors analyzed 100 NoV VP1 sequences to identify a conserved region, called region D, that differentiates between genotypes. They designed two primer sets targeting region D that are broadly reactive for genogroups I and II. Testing on a panel of 81 NoV strains showed the region D primers detected 95% of samples. Phylogenetic analysis of region D and full VP1 sequences grouped strains identically, confirming three newly identified clusters. The region D RT-PCR provides a reliable method for NoV genotyping.
1) The study analyzed HIV-1 sequences from 37 patients with high numbers (34 or more) of degenerate base codes in their protease/reverse transcriptase sequences, which can indicate either extensive viral evolution or dual infection. 2) Phylogenetic analysis of envelope and gag sequences from these patients found that 16 (43%) had dual HIV-1 infections, representing 1% of all sequences analyzed. 3) Patients with the highest numbers of degenerate base codes were more likely to have dual infections with different HIV-1 subtypes. The study demonstrates that routine HIV genotyping can help detect undiagnosed dual infections.
1. Risk Analysis DOI: 10.1111/risa.12433
A QMRA for the Transmission of ESBL-Producing
Escherichia coli and Campylobacter from Poultry Farms
to Humans Through Flies
Eric G. Evers,∗
Hetty Blaak, Raditijo A. Hamidjaja, Rob de Jonge, and Franciska M. Schets
The public health significance of transmission of ESBL-producing Escherichia coli and
Campylobacter from poultry farms to humans through flies was investigated using a worst-
case risk model. Human exposure was modeled by the fraction of contaminated flies, the
number of specific bacteria per fly, the number of flies leaving the poultry farm, and the num-
ber of positive poultry houses in the Netherlands. Simplified risk calculations for transmission
through consumption of chicken fillet were used for comparison, in terms of the number of
human exposures, the total human exposure, and, for Campylobacter only, the number of hu-
man cases of illness. Comparing estimates of the worst-case risk of transmission through flies
with estimates of the real risk of chicken fillet consumption, the number of human exposures
to ESBL-producing E. coli was higher for chicken fillet as compared with flies, but the total
level of exposure was higher for flies. For Campylobacter, risk values were nearly consistently
higher for transmission through flies than for chicken fillet consumption. This indicates that
the public health risk of transmission of both ESBL-producing E. coli and Campylobacter
to humans through flies might be of importance. It justifies further modeling of transmission
through flies for which additional data (fly emigration, human exposure) are required. Simi-
lar analyses of other environmental transmission routes from poultry farms are suggested to
precede further investigations into flies.
KEY WORDS: Campylobacter; ESBL-producing Escherichia coli; flies; poultry; risk
1. INTRODUCTION
Pathogenic microorganisms causing human dis-
ease can be transmitted to humans through food,
animals, the environment, and other humans. It is
important to quantify the attribution of this transmis-
sion between and within these sources to support a
government considering interventions to reduce pub-
lic health risk. Havelaar et al.(1)
described that for 14
pathogens that can be transmitted by food, 38% of all
Centre for Zoonoses and Environmental Microbiology, National
Institute for Public Health and the Environment, Bilthoven, The
Netherlands.
∗Address correspondence to Eric G. Evers, cZ&O, RIVM, P.O.
Box 1, 3720 BA Bilthoven, The Netherlands; tel: +31 30 2744149;
fax: +31 30 2744434; eric.evers@rivm.nl.
Dutch human disease cases is caused by foodborne
transmission.
Within foodborne transmission, chicken con-
sumption is a major contributor as it is esti-
mated to cause 20–40% of all campylobacterio-
sis cases.(2)
The relevance of transmission from
poultry to humans through the food chain was
also suggested by Leverstein-van Hall et al.(3)
in
relation to antimicrobial resistance. They demon-
strated among a set of representative clinical
extended-spectrum β-lactamase (ESBL)-producing
Escherichia coli isolates from the Netherlands,
variants that were indistinguishable from isolates
from Dutch poultry and chicken meat, with re-
spect to ESBL-gene, plasmid type, and strain
genotype.
1 0272-4332/15/0100-0001$22.00/1 C 2015 Society for Risk Analysis
2. 2 Evers et al.
Besides foodborne transmission, transmission
through the environment might also be relevant
for spread of poultry-associated zoonoses. Friesema
et al.(4)
found indirect support for significant envi-
ronmental transmission of Campylobacter to humans
when analyzing an outbreak of avian influenza in
poultry, which resulted in extensive culling, espe-
cially of laying hens, and closing of slaughterhouses.
These interventions led to a large reduction in human
campylobacteriosis cases that could not be explained
by the simultaneously occurring minor reduction in
chicken meat consumption.
A number of studies suggest that environmen-
tal transmission of pathogens to humans through
flies may be relevant. Ekdahl et al.(5)
listed six ar-
guments supporting the hypothesis of transmission
of Campylobacter through flies to humans: the low
infective dose, the ability of flies to function as a
vector, the ubiquitous presence in the environment,
the seasonality of campylobacteriosis, the age pattern
for campylobacteriosis in Western travelers to the
tropics, and the dominance of solitary human cases.
Based on this hypothesis, Nichols(6)
showed that the
seasonal character of campylobacteriosis was related
to the larval development time of the house fly Musca
domestica. Other studies focused on transmission of
pathogens to and between poultry farms as a result of
fly movements. Bahrndorff et al.(7)
found that placing
fly screens at broiler houses resulted in a reduction of
the percentage Campylobacter positive flocks from
41% to 10%. Hansson et al.,(8)
however, could not
find a relationship between the Campylobacter inci-
dence in broiler flocks and the presence of Campy-
lobacter in the environment (ground, insects, water,
feed, and ventilations shafts). Still, transmission of
Campylobacter from chicken to flies and vice versa
was indeed proven experimentally by Shane et al.(9)
The aim of this study was to investigate quan-
titatively whether transmission of ESBL-producing
E. coli and/or Campylobacter from poultry farms
through flies to humans could be a relevant transmis-
sion route in terms of public health risk.
2. MATERIALS AND METHODS
2.1. General
We used a quantitative microbial risk assessment
(QMRA) approach based on field and literature data
to estimate the public health risk of ESBL-producing
E. coli and Campylobacter on flies in the poultry
farm environment. The fly model considers events
up to and including emigration rate of the flies when
leaving the farm followed by a worst-case approach,
assuming all bacteria (ESBL-producing E. coli or
Campylobacter) on/in the flies are transmitted to hu-
mans in the vicinity of the farm. The relevance of
transmission through flies was assessed through com-
parison with QMRA estimates of exposure to and
risk of transmission through consumption of chicken
fillet, based on the idea that if worst-case fly risk is
lower than real chicken fillet risk, then fly risk is neg-
ligible in terms of public health. For ESBL-producing
E. coli only exposure was considered as there is as yet
no theoretical framework available to estimate the
type and number of human adverse health outcomes.
We chose chicken fillet for comparison as it is con-
sidered to be a food product with significant public
health risk(2,3)
for which sufficient data are available
and to a lesser extent as it also concerns chickens.
We compared the QMRA for flies with a QMRA for
chicken fillet and not with epidemiological estimates
in order to have a consistent methodology that allows
for a comparison of ESBL-producing E. coli expo-
sure estimates through both transmission routes. Re-
sulting much lower worst-case QMRA estimates for
flies compared to the QMRA estimates for chicken
fillet would make transmission through flies a neg-
ligible route; otherwise, further research would be
deemed sensible.
2.2. The Fly Model
In the model, we describe a worst-case sce-
nario for flies transmitting ESBL-producing E. coli
or Campylobacter from poultry farms (laying hens,
broilers) to humans who are present in the vicinity
of the farms (close enough to be reached by flies).
A conceptual model of the processes playing a role
in this transmission is shown in Fig. 1. In short, flies
enter the poultry farm from outside the farm area
(immigration) or develop into adults at the poultry
farm, become contaminated with ESBL-producing
E. coli and/or Campylobacter by ingestion of or con-
tact with contaminated chicken feces, leave the poul-
try farm (emigration), reach humans in the vicinity,
and transmit the bacteria to humans. This transmis-
sion can occur by mechanical dislodgement from the
flies’ exoskeleton, fecal deposition, and regurgitation
of food.(10)
At a poultry farm, one or more poultry
houses may be present, and the flies can become con-
taminated in the vicinity of the poultry house, for
example, through foraging at dung heaps or contact
3. QMRA for Transmission from Poultry Farms Through Flies 3
Fly population on farm
+: Reproduction
‐ : Death (e.g., old age, predation)
Contamination of flies with E/C
(given a contaminated farm)
Fraction of contaminated flies
No. of cfu per contaminated fly
Immigration
Emigration
Inactivation E/C
Death (old age, predation)
Fly lands on food, part of E/C
transmitted to food, food ingested
(For Campylobacter)
Dose response to illness
Cases of ilness
Farm
Environment
Human exposure
Other transmission routes
Fly is ingested
Fly lands on hand, part of E/C
transmitted to hand, touch mouth
with hand
Probability of
transmission routes
Human risk
•
•
•
•
•
•
•
•
Fig. 1. Conceptual model of transmission of bacteria from poultry farms through flies to humans. The model only considers processes up to
and including emigration, and uses a worst-case approach for the remainder of the transmission routes, assuming all bacteria in emigrating
flies to be ingested by humans. E/C = ESBL-producing E. coli / Campylobacter.
with stored manure. Flies can also enter the poultry
house itself and become contaminated, but this will
probably be less relevant for transmission to humans,
as only a small part of these flies will leave the poul-
try house. There will be a difference between laying
hen and broiler houses, these being different types of
buildings, but this is not taken into account.
We only model the process up to and including
emigration rate of the flies when leaving the farm,
followed by a worst-case approach for simplicity and
due to lack of data on emigration. We use the follow-
ing assumptions:
(i) Flies (whether or not originating from outside
the farm) can become contaminated with bac-
teria (ESBL-producing E. coli or Campylobac-
ter) on contaminated farms.
(ii) Flies may leave poultry farms.
(iii) Bacteria in/on flies are not inactivated during
emigration from poultry farms to humans.
(iv) All poultry houses at a farm are contaminated
with ESBL-producing E. coli.
(v) All laying hen houses at a farm are contami-
nated with Campylobacter.
(vi) Every separate dose of bacteria on/in a con-
taminated fly that leaves the poultry farm is in-
gested by humans.
The model output is the frequency of hu-
man exposure, the total human exposure, and (for
Campylobacter) the number of human cases of
illness.
For the model description we first consider a
farm with one poultry house, which is contaminated
with bacteria. The number of flies leaving the farm
per day during the fly season is termed fday. The num-
ber of flies leaving the farm in a year fyear equals:
fyear = fdaytfly,
where tfly is the time length of the fly season in days.
The fly season is defined by a much higher number
of flies on the farm compared to the rest of the year.
The number of contaminated flies leaving the farm in
a year f cont
year (= the number of exposures) equals:
f cont
year = fyear pfly,
where pfly is the fraction of contaminated flies given
a farm with a contaminated poultry house. The to-
tal number of bacteria (ESBL-producing E. coli or
Campylobacter) that is transmitted to humans in the
vicinity (within reach of flies) of the farm in a year
dyear (= the total exposure) equals:
dyear = f cont
year dfly,
where dfly is the number of bacteria in/on a contami-
nated fly.
The number of human cases of illness (campy-
lobacteriosis) in the vicinity of the farm in a year cill
equals:
cill = pill f cont
year ,
4. 4 Evers et al.
where pill is the probability of illness after ingesting
the dose of bacteria in/on a contaminated fly, which
equals:
pill = pill|inf pinf ,
where pill|inf is the probability of illness given in-
fection and pinf is the probability of infection after
ingesting the mean dose of bacteria in/on a contam-
inated fly, which is described by the Beta Poisson
dose-response model:(11)
pinf = 1 − 1 +
dfly
β
−α
,
with α and β parameters.
All model outputs above are outputs per poultry
house, as more than one poultry house may be lo-
cated on a farm. Note that this does not mean that
flies originating from inside the poultry houses are
the main risk. On the contrary, we think that the
main contribution to transmission will be due to flies
that become contaminated on the farm, but in the
environment of the poultry house. To obtain results
for the Netherlands as a whole, we multiplied with
the number of contaminated poultry houses in the
Netherlands. So the number of contaminated flies
leaving contaminated poultry farms in a year in the
Netherlands Fcont
year , the total number of bacteria that
is transmitted to humans in the vicinity of a contami-
nated poultry farm in a year in the Netherlands Dyear,
and the number of human cases of illness in the vicin-
ity of a contaminated poultry farm in a year in the
Netherlands Cill equal:
Fcont
year = f cont
year Nph pph,
Dyear = dyear Nph pph,
Cill = cill Nph pph,
where Nph is the number of poultry houses in the
Netherlands and pph is the fraction of contaminated
poultry houses in the Netherlands.
2.3. The sQMRA Chicken Fillet Model
The swift quantitative microbiological risk as-
sessment (sQMRA) model is a simplified QMRA
approach using a food chain model with measure-
ments of a food product in retail as the starting
point and human cases as the end point. The first de-
terministic version(12)
focused on heating and cross-
contamination during food preparation by the con-
sumer. Chardon and Evers(13)
presented a second
(extended) probabilistic version, which in addition
includes variability of food treatment by the con-
sumer, growth or inactivation during food storage at
the consumers’ home, and the D/z-heating model (14)
for food preparation. In that paper, an example
calculation for Campylobacter on chicken fillet was
given, the results of which are used here. For ESBL-
producing E. coli on chicken fillet, analogous calcula-
tions are done with the bacterium-specific parameter
values adjusted.
2.4. The Poultry Farm Field Study
2.4.1. Measurements
Data for pfly (the fraction of contaminated flies
given a farm with a contaminated poultry house)
and dfly (the number of bacteria in/on a contami-
nated fly) originate from a study on the prevalence
and number of ESBL-producing E.coli and Campy-
lobacter on flies on Dutch poultry farms.(15,16)
Dur-
ing 2011 and 2012, three broiler farms and five laying
hen farms were visited and sampled. At one of the
broiler farms, flies were collected during four differ-
ent visits (two times during the presence of broilers
and two times during/after cleaning in the absence
of broilers), at the remainder of the farms, flies
were collected during one visit during which chickens
were present. In total, 326 flies (of which 212 Musca
domestica) were caught at the farms, in or near
poultry houses (e.g., manure storage, canteen, egg
sorting area). Flies were collected, transported, and
processed as described by Blaak et al.(15)
Flies were analyzed in pools, each consisting of
one to eight flies of the same species and collected at
the same location. All 326 flies were analyzed for the
presence of ESBL-producing E. coli (73 pools), 297
(of which 202 Musca domestica) were analyzed for
Campylobacter (65 pools). Flies were homogenized
in PBS/0.5% Tween20. For the isolation of ESBL-
producing E. coli, fly homogenates were plated on
ChromID ESBL medium (Biomerieux, Boxtel, The
Netherlands) and 10 mL of the fly homogenates was
additionally enriched in BPW/1 μg/mL cefotaxime
followed by plating on ChromID ESBL medium. In-
cubations were performed for 4 to 5 hours at 36 ±
2 °C, followed by 21 ± 3 hours at 44 ± 0.5 °C. Sus-
pected ESBL-producing isolates were confirmed as
ESBL-producers using disk-diffusion and sequencing
of ESBL-genes.(15)
For the isolation of Campylobac-
ter 10 mL portions of fly homogenates were enriched
in Preston broth, followed by plating on CCDA agar
(Oxoid, Landsmeer, The Netherlands). Incubations
5. QMRA for Transmission from Poultry Farms Through Flies 5
of enrichments in Preston broth as well as CCDA
agar plates were performed microaerobically using
CampyGen sachets (Oxoid B.V., Landsmeer, The
Netherlands), for 44 ± 4 hours at 41.5 ± 1 °C.
On fly collection days, manure and/or wastewa-
ter from the farm was also collected to test for ESBL-
producing E. coli and Campylobacter.
2.4.2. Calculations
We estimate the value of pfly (the fraction of
contaminated flies given a farm with a contaminated
poultry house) through maximizing the likelihood
equation L, where, assuming that pfly is a constant
for positive farms:
L =
i
ni
ki
pki
fly(1 − pfly)ni −ki
,
which is simply the product of binomial distributions
per pooled sample, with ni and ki the total number
and the number of positive flies in pool i, respec-
tively. This can be simplified to:
L = (1 − pfly)n0
i
(1 − (1 − pfly)ni,pos
)
or
ln L = n0 ln(1 − pfly) +
i
ln(1 − (1 − pfly)ni,pos
),
where the part of the equation left of the +sign repre-
sents negative pools with n0 the total number of flies
in negative pools and the part of the equation right
of the +sign represents the positive pools with ni,pos
the number of flies in positive pool i.
The number of bacteria (ESBL-producing E. coli
or Campylobacter) in a positive fly in pool i, dfly,i, is
calculated with:
dfly,i =
ni,pos
j=1 Bin j|ni,pos, pfly
dpool,i
j
1 − Bin(0|ni,pos, pfly)
,
where dpool,i is the total number of bacteria in pool
i. The formula calculates the average number of bac-
teria in a positive fly, weighted with the probability
of j positive flies in the pool. The number of bacteria
in a positive fly, dfly, is then calculated by taking the
average of the dfly,i values.
All calculations were done with Microsoft Excel,
using the Solver function to estimate pfly.
2.5. Parameter Values
For all fly model parameter values other than
ESBL-producing E. coli pfly and dfly, and for the
chicken fillet model parameter values, data or ad-
ditional data were mainly obtained from literature,
but also from unpublished own research, and through
personal communication. The estimated parameter
values are given in Tables I–V. The data used to ob-
tain these values are described in Sections 3.1–3.4.
3. RESULTS
3.1. Fly Migration Behavior Parameters
fday (the number of flies leaving the farm per day)
The influx of flies (Diptera: Brachycera) into
broiler houses was estimated by Hald et al.(17)
at 6,524
± 638 (standard error) flies per broiler rotation, or
186 flies per day, setting 35 days per rotation. Hald
et al.(18)
found 917 flies per day during the last week
of rotation, which was explained by the increased vol-
ume (m3
/hours) of ventilation air inflow. We used
the value of Hald et al.(17)
as an estimate of the flux
of flies towards the poultry house and its possibly
contaminated vicinity (e.g., dung and manure heaps),
the flies originating from the wider farm terrain or
abroad (e.g., other farms). This value was used as the
basis to estimate fday, the number of flies per day leav-
ing the farm and possibly contaminating humans.
For this, release-recapture experiments of flies
on farms were used as these give an estimate of the
fraction of released flies that remain on and that
leave the farm. Lysyk and Axtell(19)
released marked
house flies in the poultry house on two livestock farm
locations containing a dairy, poultry houses, build-
ings, pastures, and ungrazed fields. Of the flies re-
captured after five days, a fraction of 0.17 came from
field and pasture. Recaptured fly numbers were low
farther than 50 m away from the release point, so the
value of 0.17 constitutes a maximum estimate, also as
flies that are eaten will not be recaptured.
Using the data above, the number of flies leaving
the farm per day fday was estimated at 0.17 × 186 =
32.
tfly (duration of the fly season in days)
We will work from the starting point of a
season-dependent fly population size, although on
a cattle/pig farm in Denmark, Kristiansen and
Skovmand(20)
found a relation of fly population size
with manure presence rather than with the month
of the year. Hald et al.(18)
stated that the fly season
6. 6 Evers et al.
Table I. Parameter Values of the Fly Model
Parameter ESBL-Producing E. coli Campylobacter
Symbol Definition Broiler Laying Hen Broiler Laying Hen
fday Number of flies leaving the farm per day 32 32 32 32
tfly Duration of the fly season in days 91 91 91 91
pfly Fraction of contaminated flies given a
farm with a contaminated poultry
house
0.048 0.031 0.137 0.137
dfly Number of bacteria in/on a contaminated
fly
1.96E4 1.28E3 2.5E2 2.5E2
pill|inf
The probability of illness given infection – – 0.33 0.33
α Parameter of the Beta Poisson
dose-response model
– – 0.145 0.145
β Parameter of the Beta Poisson
dose-response model
– – 7.589 7.589
Nph Number of poultry houses in the
Netherlands
2212 1974 2212 1974
pph Fraction of contaminated poultry houses
in the Netherlands
1 1 0.45 1
around broiler houses stretches from April to Octo-
ber, with a peak in abundance and activity in July
and August. Meerburg et al.(10)
stated that house
flies (Musca domestica) can be found near pig farms
from spring to October, with 10–12 generations of
15–25 days. Skovgard and Nachman(21)
found a large
population of stable flies (Stomoxys calcitrans) on a
dairy farm from June/July to September. So flies will
be present for about seven months per year, but in
higher numbers for some three months (= 91 days),
which we will use as a value for tfly.
3.2. Contamination of Flies and Human
Dose-Response Parameters
3.2.1. Poultry Farm Field Study
All farms were (manure/wastewater)-positive for
ESBL-producing E. coli at fly sampling days. The
data on absence/presence and numbers of ESBL-
producing E.coli in flies are shown in Tables II and
III together with the estimated pfly (the fraction of
contaminated flies given a farm with a contaminated
poultry house) and dfly (the number of bacteria in/on
a contaminated fly).
The higher mean number of ESBL-producing
E. coli in flies from broiler farms compared to lay-
ing hen farms is in agreement with measurements in
fresh chicken feces sampled at the same time as the
flies. Geometric mean concentrations were 2.3 × 104
CFU/g in broiler faeces (39 samples, three farms) and
5.0 × 102
CFU/g in laying hen feces (27 samples, five
farms).(16)
All laying hen farms and two out of three broiler
farms were Campylobacter-positive; at the farm that
was sampled multiple times, Campylobacter was de-
tected at one of the four visits. For 13 of 22 fly pools
from broiler farms, the farms were Campylobacter-
negative at time of sampling. All flies were negative
for Campylobacter (Table IV).
3.2.2. Literature Data
In the literature we found no data on ESBL-
producing E.coli in flies, but in a number of stud-
ies Campylobacter in or on flies was investigated,
showing a very large range of the percentage of
Campylobacter positive flies pfly (Table IV). We did
not include fly prevalence data from other farms
than laying hens and broilers. In the investigation
of Rosef and Kapperud,(22)
the pathogen was identi-
fied as Campylobacter fetus subsp. jejuni from house
flies, which is interpreted as Campylobacter spp. (per-
sonal communication, Jacobs-Reitsma, RIVM, The
Netherlands). Berndtson et al.(23)
did not specify the
exact pool sizes; pooled samples contained one to six
flies. The results were analyzed with the same maxi-
mum likelihood approach as described in Section 2.4,
taking the mean of scenarios of pools of size one
to six to obtain the estimates in Table IV. Hansson
et al.(8)
did investigate the broiler farms for Campy-
lobacter spp. but the accumulated data do not allow
7. QMRA for Transmission from Poultry Farms Through Flies 7
Table II. Data on Number of Collected Flies, Their ESBL-Producing E. coli Status and the Estimated pfly
Variable Description Broiler Farm Laying Hen Farm
Total no. of pools 29 44
No. of negative pools 24 38
No. of positive pools 5 6
Total no. of flies 117 209
No. of negative flies 88 178
Pool size of positive pools 3, 8, 8, 2, 8 8, 8, 8, 2, 4, 1
estimated pfly 0.048 0.031
Table III. Data on Detected Numbers of ESBL-Producing E. coli in Fly Pools, and Estimated dfly,i and dfly
Poultry Pool Size ESBL-Producing Estimated Estimated
Farm (No. of E. coli Number in Pool dfly,i dfly
Type Flies) (CFU/Pool) (CFU/Positive Fly) (CFU/Positive Fly)
Broiler 3 2.54E+04 2.48E+04 1.96E+04
8 4.95E+02 4.53E+02
8 1.65E+02 1.51E+02
2 1.98E+03 1.96E+03
8 7.69E+04 7.04E+04
Laying hen 8 1.16E+03 1.09E+03 1.28E+03
8 4.95E+02 4.68E+02
8 8.41E+01 7.95E+01
2 4.13E+03 4.09E+03
4 8.25E+02 8.06E+02
1 1.16E+03 1.16E+03
to relate the Campylobacter status of the flies to
the Campylobacter status of the farms. However, the
farms could be distinguished into often, intermedi-
ate, or rarely positive in the past three years and we
excluded the last category for the calculation of the
mean Campylobacter prevalence of flies. Again, for
the individual fly prevalence estimates we took the
mean of maximum likelihood estimates for pools of
size 1–25, as pool size was not exactly specified.
Few or none of the data in Table IV would be
useful to estimate pfly, the fraction of contaminated
flies given a farm with a contaminated poultry house,
when strict criteria would be applied. These criteria
are: (i) the poultry farms are to be Campylobacter
positive and (ii) no other Campylobacter positive an-
imals are to be present in the vicinity (as these could
also contaminate the flies). We decided to use the
majority of the data in Table IV, accepting the short-
comings, in order to obtain a rough estimate of pfly,
excluding Campylobacter- negative farms where pos-
sible, and the “farm near pigs” from Hald et al.(17)
as the pigs were probably Campylobacter- positive.
Also, we excluded the PCR data (as only viable
campylobacters are relevant) and did not distinguish
between Campylobacter species. The considerations
above resulted in an estimated mean value of 0.137
for pfly.
There are no data on numbers of Campylobac-
ter on or in flies (dfly). Therefore, we estimated these
numbers from data on food consumption rate and
activity time span of flies, and the concentration of
Campylobacter in chicken feces. It is thus assumed
that the amount of Campylobacter on the surface of
a fly is of less importance than the campylobacters in
its inside, based on Shane et al.(9)
They exposed flies
(Musca domestica) to a Campylobacter solution and
isolated Campylobacter from the feet and ventral sur-
face of 14% of the flies, and from the viscera of 81%
of the flies.
Kobayashi et al.(24)
measured an ingested
amount of trypticase soy broth by houseflies (Musca
domestica vicina) of 3.35 μL ࣈ 3.35 mg after 30 min.
Shepard et al.(25)
measured a maximum of 6 hours of
activity of flies (Musca domestica) in 8 hours. This
equals 9 hours of activity for a daylight length of
12 hours. Considering one day and assuming all ac-
tivity is feeding, the ingested volume is 9 × 2 ×
3.35 = 60 mg. Hutchison et al.(26)
found the mean
9. QMRA for Transmission from Poultry Farms Through Flies 9
Campylobacter concentration in positive fresh poul-
try feces in the United Kingdom to be 4.2E3 CFU/g.
So then dfly, the number of Campylobacter in a con-
taminated fly, can be estimated to be 60E−3 g ×
4.2E3 CFU/g = 2.5E2 CFU. This is a maximum es-
timate in the sense that this number will in reality be
lower due to regurgitation, defecation, and inactiva-
tion in the alimentary tract.(27)
The effect of ingested campylobacters on hu-
mans is described in terms of the probability of in-
fection pinf and illness pill. The equations are given in
Section 2.2. The parameter values used are α = 0.145,
β = 7.589,(11)
and pill|inf = 0.33,(28)
based on human
volunteer studies.
3.3. Poultry Farm Parameters
The number of active broiler and laying hen
farms in the Netherlands in 2013 was 774 and 896, re-
spectively. The average number of broiler and laying
hen houses per farm was 2.86 and 2.20, respectively.
So the number of broiler and laying hen houses in the
Netherlands Nph was estimated at 2,212 and 1,974,
respectively (personal communication, Erik Bout,
Dutch Product Boards for livestock, meat, and eggs).
Dierikx et al.(29)
measured ESBL-producing
E.coli in 26 broiler farms in the Netherlands in the
period March–June 2009. Based on 25–41 cloaca
swabs per farm, all farms were found positive for
ESBL-producing E. coli. Huijbers et al.(30)
found all
50 broiler farms investigated in the Netherlands in
July 2010–April 2011 positive for ESBL-producing E.
coli. This was based on cloaca swabs from 20 broilers
taken from all houses from a farm, with a minimum
of one positive pool sample of two swabs as a cri-
terion. In our field study we found ESBL-producing
E. coli in feces in all investigated broiler and laying
hen farms. Based on all the above observations, pph
(the fraction of contaminated poultry houses in the
Netherlands) was set to 1 for broiler and laying hen
farms.
Jore et al.(31)
gave monthly surveillance data for
Campylobacter in Dutch broiler flocks for the period
2001–2007. The highest mean prevalence for a three-
month period was reported for June–August or July–
September and equaled 0.45. This value was chosen
for pph. It agrees with the six of 12 (50%) positive
sampling events at three broiler farms in 2011–2012
in the poultry house field study.
The Campylobacter prevalence for laying hen
flocks is unknown. Given that laying hens get rel-
atively old (about 80 weeks, whereas broilers are
culled after six weeks), the assumption that these an-
imals are Campylobacter positive for the main part
of their life seems realistic (personal communication,
Jacobs-Reitsma, RIVM, The Netherlands). This is in
agreement with our field study where we found 10 of
10 (100%) positive sampling events at five laying hen
farms in 2011–2012. Therefore, pph is set to 1.
3.4. Chicken Fillet Parameters
The ESBL-producing E. coli data used for the
sQMRA calculations are given in Table V. Data
for percentage contamination and concentration
of ESBL-producing E. coli on conventional retail
chicken fillets were obtained from two Dutch stud-
ies. A lognormal distribution was fitted to the con-
centration data of each study. For 60 chicken fillets
sampled in 2010(32)
this resulted in 100% contami-
nated chicken fillets with mean and standard devia-
tion for the ESBL-producing E. coli concentration of
11.4 and 48.0 CFU/g, respectively. Of 140 chicken fil-
lets sampled in 2011, 99.3% were contaminated with
ESBL-producing E. coli and mean and standard de-
viation for the ESBL-producing E. coli concentration
were 5.8 and 31.9 CFU/g, respectively (unpublished
data, Dutch Consumers Association/RIVM). For the
sQMRA calculation we used the average values from
both studies for the three parameters: 99.7% contam-
inated chicken fillets and a mean and standard devi-
ation for the concentration of 8.57 and 39.92 CFU/g,
respectively.
3.5. Comparison of the Risk of Transmission
Through Flies and Chicken Fillet
The model outputs in terms of human expo-
sure for ESBL-producing E. coli and human expo-
sure and illness for Campylobacter through contact
with flies (broiler, laying hen) and consumption of
chicken fillet are shown in Table VI. Note that the
number of exposures is the number of contaminated
flies originating from a poultry farm, or the number
of consumed contaminated chicken fillets, in a year.
The total exposure is the number of ingested ESBL-
producing E. coli or Campylobacter in a year. Note
also that the fly estimates are worst-case estimates,
which is illustrated by the Campylobacter results at
poultry-house level: we estimate the very high value
of 52 campylobacteriosis cases per year per positive
broiler or laying hen house, 52 cases being caused by
394 exposures.
10. 10 Evers et al.
Table V. ESBL-Producing E. coli Parameter Values Used for the sQMRA Calculations
Parameter Subgroup Parameter Description Parameter Value Explanation
Contamination level at retail Percentage of contaminated
chicken fillets
99.7 % For explanation see text.
Mean concentration 8.57 CFU/g
Standard deviation of
concentration
39.92 CFU/g
Growth and inactivation
during storagea
Minimum generation time 0.30 hours Value for ground mutton from Table 1b
“Temperature and Growth.”
Optimum growth temperature 37.5 °C From Table D “Limits for growth.”
Minimum growth temperature 7.5 °C From Table D “Limits for growth.”
Probability of survival per
CFU and day at room
temperature
1 d−1 Assumption based on the fact that Table
1a “Temperature and survival” gives
no data at room temperature.
Probability of survival per
CFU and day in the
refrigerator
0.896 d−1 Based on the reported reduction of about
a factor 10 in about three weeks in the
section “Growth and survival
characteristics.”
Probability of survival per
CFU in the freezer
0.1 Based on the reported reduction of a
factor of 10 after 38 weeks at −25.5 °C
for nonpathogenic E. coli in the section
“Growth and survival characteristics.”
Inactivation due to heating
during food preparation
D value at the reference
temperature Dref
0.21 min Using the values for E. coli from van
Asselt and Zwietering.(14)
z value 10.6 °C
Reference temperature Tref 70 °C
aData were obtained from Chapter 7 “Intestinally pathogenic Escherichia coli” from ICMSF.(37)
Table VI. Comparison of Exposure and Illness Between Transmission Through Flies (Worst-Case Approach) and Chicken Fillet
No. of Total Exposure No. of Cases
Transmission Exposures (No. of Bacteria) (cill, Cill)
Bacterium Route Level Type ( f cont
year ,Fcont
year ) (dyear, Dyear)
ESBL-producing
E. coli
Fly Positive poultry
housea
Broiler 1.4E+02 2.7E+06
Laying hen 8.9E+01 1.1E+05
The Netherlands Broiler 3.1E+05 6.0E+09
Laying hen 1.8E+05 2.3E+08
Chicken fillet The Netherlands – 4.1E+06 1.5E+08
Campylobacter Fly Positive poultry
housea
Broiler 3.9E+02 9.9E+04 5.2E+01
Laying hen 3.9E+02 9.9E+04 5.2E+01
The Netherlands Broiler 3.9E+05 9.8E+07 5.2E+04
Laying hen 7.8E+05 1.9E+08 1.0E+05
Chicken fillet The Netherlands – 4.6E+05 1.8E+07 1.1E+04
aIncluding the vicinity of the poultry house.
Focusing on public health risk, thus on the level
of the whole of the Netherlands, for ESBL-producing
E. coli the number of exposures is higher for chicken
fillet than for flies, but the total exposure is higher
for flies than for chicken fillet (Table VI). For broiler
flies, total exposure is a factor 40 higher than for
chicken fillet; for laying hen flies a factor 1.5. The
higher values for broiler flies compared to laying hen
flies are mainly caused by the higher pfly (the fraction
of contaminated flies given a farm with a contami-
nated poultry house) and dfly (the number of bacteria
in/on a contaminated fly).
For Campylobacter, the number of exposures
through chicken fillet is in between that through flies
11. QMRA for Transmission from Poultry Farms Through Flies 11
from broilers and laying hens (Table VI). The total
exposure and the number of cases is higher for flies
than for chicken fillet, with a factor of about 5 for
broiler flies and about 10 for laying hen flies. The
higher values for laying hen flies compared to broiler
flies are caused by the higher laying hen value of pph
(the fraction of contaminated poultry houses in the
Netherlands).
4. DISCUSSION
Our results, which are based on the currently
available knowledge, imply that transmission of both
ESBL-producing E. coli and Campylobacter through
flies to humans cannot be considered a negligible
public health risk and further research is sensible.
The basis for this conclusion is a comparison of a
worst-case risk assessment for transmission of bac-
teria through flies with a simplified risk assessment
for transmission of bacteria through consumption
of chicken fillet. A worst-case approach implies of
course that the real value can be any value lower than
or equal to the estimated value. An obvious next step
would be the replacement of the worst-case estimates
for transmission through flies with realistic estimates,
while retaining the relative risk approach by compar-
ing with the risk of chicken fillet consumption. This
would comprise of an improvement of the emigration
value fday and extension of the model to incorporate
processes during and after emigration.
An alternative approach to estimate the emigra-
tion flux of flies would be to use the results of release-
recapture studies. In our opinion, these studies are,
however, suitable to estimate relative numbers rather
than absolute fluxes of flies. This relates to the com-
plexity of the dynamics of the fly population on a
farm, which includes population size, birth rate, pre-
dation, death rate, immigration, emigration, and ei-
ther or not a steady state situation together with the
unknown fraction of nonrecaptured flies. Therefore,
we preferred to use the number of 186 flies per day(17)
as a basis with the important advantage of being a
real measured number. We are aware of course this
is a poultry house influx number, but we see it as a
number that gives an idea of the size of immigration
and emigration fluxes that is usable for a worst-case
QMRA approach. Next, we assumed that this num-
ber of 186 flies can be seen as analogous to released
flies in a release-recapture study. We used the result
of the Lysyk and Axtell study,(19)
which can be in-
terpreted as that a maximum of 17% of the flies will
leave the farm.
Processes during and after emigration include
(Fig. 1): inactivation of ESBL-producing E. coli and
Campylobacter on/in flies during their flight to hu-
mans; death of the flies before reaching humans; the
probability of actually reaching humans; the proba-
bility of each possible transmission route to occur;
and properties of specific transmission routes (e.g.,
fraction of bacteria transmitted from flies to human
food). These are all aspects with no or scarce data
availability, which was an important reason to follow
the worst-case approach applied here.
Skovgard et al.(27)
did study the inactivation
of Campylobacter in artificially inoculated flies, but
their results do not allow for a quantitative estimate
of Campylobacter inactivation rate as only absence or
presence was measured, which in addition is related
to the detection limit. An example result is that at low
and high dose and 15 °C 1% of the flies are still car-
riers ca. 48 hours and 60–70 hours after inoculation,
respectively.
The probability of flies actually reaching humans
will be related to human population density as a func-
tion of the distance from the poultry farms and the
fly range of the flies. Data on fly range of flies are,
however, limited. Based on laboratory experiments
of Shepard et al.,(25)
the flight range per day for five-
day-old flies can be estimated at 5.4 km. Recapture
field experiments at a poultry farm by Nazni et al.(33)
showed that a flight distance of 4 km or more seldom
occurs.
The uncertainty of pfly, the fraction of
Campylobacter- positive flies given a contami-
nated poultry house, obtained from the poultry
house field study and literature data, is large (Table
IV). It was noted that the percentage of positive
flies decreased with the publication year of the
study, being higher in older studies and lowest in
more recent studies. The Campylobacter detection
method was more or less similar in all studies;
however, high percentages of positive flies were
found in the older studies where laboratory analysis
started within four or six hours after fly capture,(22,23)
this period being 24 hours or longer in the more
recent studies. Live transportation of the flies to
the laboratory, as practiced and stated to be im-
portant for reliable Campylobacter detection,(17,18)
does not give high pfly values in combination with
these longer capture-analysis time periods. Possi-
bly, the Campylobacter die-off on/in flies is rapid,
which is supported by the much higher percentage
of positive flies detected by PCR as compared to
conventional culture.(18)
In our opinion, the data did
12. 12 Evers et al.
not sufficiently support the use of the higher values
only(22,23)
(which besides are unlikely to be false pos-
itives). Therefore, we chose to use the mean value
of the percentages Campylobacter obtained in the
various studies. Alternatively, this can be regarded
as implicitly including Campylobacter inactivation
during the flight of the flies from the poultry farm to
humans.
A possibly relevant extension of the model could
be to distinguish between free-range poultry farms
and farms where chickens stay inside. When chickens
are outside, their (fresh) feces are easier accessible
for flies. In addition, Campylobacter flock prevalence
in free-range chickens and chickens at conventional
farms may differ. Hoogenboom et al.(34)
reported
Campylobacter presence in feces at all nine sam-
pled organic free-range broiler farms (100%) in 2005,
whereas the Campylobacter prevalence was 22% in
289 conventional broiler flocks in 2001 to 2002.(35)
When transmission through flies would prove to
be of significant importance, the development of in-
tervention strategies becomes relevant. The use of
fly screens, which was shown to reduce Campylobac-
ter broiler flock prevalence from 41% to 10%,(7)
is a possibility (although not for free-range poultry
farms). This would extend the functionality of these
screens from prevention of transmission between
poultry farms to include prevention of transmission
from poultry farms to humans. Another possibility
would be to reduce the size of the fly popu-
lation on poultry farms by preventive measures,
such as rapid removal of waste and manure, stor-
ing waste in well closable containers and keeping
manure covered, and cleaning the poultry houses
regularly.
The study of Friesema et al.(4)
suggests a signif-
icant transmission of Campylobacter from poultry
farms to humans through the environment. Apart
from flies, air, soil, and water are also relevant for
environmental transmission of bacteria, with water
and air presumably being the most relevant. From
poultry farms, bacteria can enter the surface water
surrounding the farm by runoff to ditches. Humans
can be exposed to contaminated surface water
during swimming activities, or through consumption
of irrigated agricultural crops. An estimation of the
relative importance of the different environmental
transmission routes can be obtained by performing
worst-case or simplified QMRA calculations (e.g.,
Evers et al.(36)
). A subsequent extensive QMRA of
the apparent most important environmental trans-
mission route then is to result in recommendations
for risk management on interventions to reduce
public health risk of ESBL-producing E. coli and
Campylobacter.
ACKNOWLEDGMENTS
The authors thank Lianne Kerkhof - de Heer
and Angela van Hoek for their assistance in the field
and laboratory work, and Wilma Jacobs-Reitsma for
helpful discussions. This study was conducted on be-
half of the Netherlands Food and Consumer Product
Safety Authority.
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