title: Infection-interactions in Ethiopian village chickens.
abstract: Chickens raised under village production systems are exposed to a wide variety of pathogens, and current or previous infections may affect their susceptibility to further infections with another parasite, and/or can alter the manifestation of each infection. It is possible that co-infections may be as important as environmental risk factors. However, in cross-sectional studies, where the timing of infection is unknown, apparent associations between infections may be observed due to parasites sharing common risk factors. This study measured antibody titres to 3 viral (Newcastle disease, Marek's disease and infectious bursal disease) and 2 bacterial (Pasteurella multocida and Salmonella) diseases, and the infection prevalence of 3 families of endo- and ecto-parasites (Ascaridida, Eimeria and lice) in 1056 village chickens from two geographically distinct populations in Ethiopia. Samples were collected during 4 cross-sectional surveys, each approximately 6 months apart. Constrained ordination, a technique for analysis of ecological community data, was used to explore this complex dataset and enabled potential relationships to be uncovered and tested despite the different measurements used for the different parasites. It was found that only a small proportion of variation in the data could be explained by the risk factors measured. Very few birds (9/1280) were found to be seropositive to Newcastle disease. Positive relationships were identified between Pasteurella and Salmonella titres; and between Marek's disease and parasitic infections, and these two groups of diseases were correlated with females and males, respectively. This may suggest differences in the way that the immune systems of male and female chickens interact with these parasites. In conclusion, we find that a number of infectious pathogens and their interactions are likely to impact village chicken health and production. Control of these infections is likely to be of importance in future development planning.
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom; International Livestock Research Institute, Addis Ababa, Ethiopia. Electronic address: judybett@liv.ac.uk.
authors.forename: J M
authors.initials: JM
authors.lastname: Bettridge
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom; International Livestock Research Institute, Addis Ababa, Ethiopia.
authors.forename: S E
authors.initials: SE
authors.lastname: Lynch
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom.
authors.forename: M C
authors.initials: MC
authors.lastname: Brena
authors.affiliation: Debre Zeit Agricultural Research Centre, Ethiopian Institute for Agriculture Research, Debre Zeit, Ethiopia.
authors.forename: K
authors.initials: K
authors.lastname: Melese
authors.affiliation: International Livestock Research Institute, Addis Ababa, Ethiopia.
authors.forename: T
authors.initials: T
authors.lastname: Dessie
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom; International Livestock Research Institute, Addis Ababa, Ethiopia.
authors.forename: Z G
authors.initials: ZG
authors.lastname: Terfa
authors.affiliation: International Livestock Research Institute, Addis Ababa, Ethiopia; Centre for Genetics and Genomics, School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: T T
authors.initials: TT
authors.lastname: Desta
authors.affiliation: School of Biology, Newcastle University, Newcastle Upon Tyne, NE1 7RU, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Rushton
authors.affiliation: Centre for Genetics and Genomics, School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: O
authors.initials: O
authors.lastname: Hanotte
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Science, University of Edinburgh, Midlothian EH25 9RG, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Kaiser
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Wigley
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Leahurst Campus, Liverpool CH64 7TE, United Kingdom; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, L69 7BE, United Kingdom.
authors.forename: R M
authors.initials: RM
authors.lastname: Christley
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001424:Bacterial Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D002645:Chickens; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary* / Q000821:virology; D003430:Cross-Sectional Studies; D017753:Ecosystem; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D008297:Male; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000821:virology*; D025341:Principal Component Analysis; D012307:Risk Factors; D014777:Virus Diseases / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology
chemical_list: D000907:Antibodies, Bacterial; D000914:Antibodies, Viral
keywords: Co-infection; Constrained ordination; Ethiopia; Host-parasite interaction; Village chicken
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