title: Sero-epidemiology of Peste des petits ruminants virus infection in Turkana County, Kenya.
abstract: BACKGROUND
  Peste des petits ruminants (PPR) is a contagious viral disease of small ruminants. Serum samples from sheep (n = 431) and goats (n = 538) of all ages were collected in a cross-sectional study in Turkana County, Kenya. The objective was to estimate the sero-prevalence of PPR virus (PPRV) infection and associated risk factors in both species. PPRV competitive enzyme-linked immuno-sorbent assay (c-ELISA) analysed the presence of antibodies in the samples. All analyses were conducted for each species separately. Multivariable logistic regression models were fitted to the data to assess the relationship between the risk factors and PPRV sero-positivity. Mixed-effect models using an administrative sub-location as a random effect were also fitted to adjust for possible clustering of PPRV sero-positivity. Intra-cluster correlation coefficients (ρ) that described the degree of similarity among sero-positive responses for each species in each of the six administrative divisions were estimated.
  
  
  RESULTS
  Goats had a significantly higher sero-prevalence of 40% [95% confidence interval (CI): 36%, 44%] compared to sheep with 32% [95% CI: 27%, 36%] (P = 0.008). Combined sero-prevalence estimates were heterogeneous across administrative divisions (n = 6) (range 22% to 65%) and even more across sub-locations (n = 46) (range 0% to 78%). Assuming that PPRV antibodies are protective of infection, a large pool of PPRV susceptible middle age group (>6 months and < 24 months) in both species was estimated. This was based on the low sero-prevalence in this group in goats (14% [95% CI: 10%, 20%]) and in sheep (18% [95% CI: 13%, 25%]). Regression analysis returned significant risk factors across species: in sheep - vaccination status, age and administrative division; in goats - sex, age, administrative division and sex*age interaction. The intra-sub-location correlation coefficients varied widely across divisions (range <0.001 to 0.42) and across species within divisions.
  
  
  CONCLUSIONS
  Biological, spatial and socio-ecological factors are hypothesized as possible explanations for variation in PPRV sero-positivity in the Turkana pastoral ecosystem.
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. simon.kihu@vetworks-ea.org.|Vetworks Eastern Africa, PO Box 10431-00200, Nairobi, Kenya. simon.kihu@vetworks-ea.org.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Kihu
authors.affiliation: Kenya Agricultural Research Institute -Trypanosomiasis Research Institute, PO Box 362-00902, Kikuyu, Kenya. J.Gachohi@cgiar.org.|International Livestock Research Institute (ILRI), PO Box 30709-00100, Nairobi, Kenya. J.Gachohi@cgiar.org.
authors.forename: John M
authors.initials: JM
authors.lastname: Gachohi
authors.affiliation: Kenya Agricultural Research Institute -Veterinary Research Centre, PO Box 32-00902, Kikuyu, Kenya. eunicekndungu@yahoo.com.
authors.forename: Eunice K
authors.initials: EK
authors.lastname: Ndungu
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. cggitao@gmail.com.
authors.forename: George C
authors.initials: GC
authors.lastname: Gitao
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. lilybebora@yahoo.com.
authors.forename: Lily C
authors.initials: LC
authors.lastname: Bebora
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. njengamunene@yahoo.com.
authors.forename: Njenga M
authors.initials: NM
authors.lastname: John
authors.affiliation: Faculty of Arts, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya. wairireg@gmail.com.
authors.forename: Gidraph G
authors.initials: GG
authors.lastname: Wairire
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. ndichu@uonbi.ac.ke.
authors.forename: Ndichu
authors.initials: N
authors.lastname: Maingi
authors.affiliation: Faculty of Veterinary Medicine, University of Nairobi, PO Box 29053-00625, Uthiru, Kenya. rgwahome@gmail.com.
authors.forename: Raphael G
authors.initials: RG
authors.lastname: Wahome
authors.affiliation: Kenya Agricultural Research Institute -Veterinary Research Centre, PO Box 32-00902, Kikuyu, Kenya. ricky.ireri@gmail.com.
authors.forename: Ricky
authors.initials: R
authors.lastname: Ireri
mesh_terms: D000818:Animals; D005260:Female; D015511:Goat Diseases / Q000453:epidemiology / Q000821:virology*; D006041:Goats; D007630:Kenya / Q000453:epidemiology; D008297:Male; D029021:Peste-des-Petits-Ruminants / Q000097:blood / Q000453:epidemiology*; D015995:Prevalence; D016036:Seroepidemiologic Studies; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000821:virology*; D013045:Species Specificity