title: Cross-sectional serosurvey and associated factors of bluetongue virus antibodies presence in small ruminants of Nepal.
abstract: BACKGROUND
  Bluetongue (BT) is an infectious, insect-borne viral disease primarily affecting sheep and occasionally cattle and goats. In Nepal, BT is an emerging disease of economic importance. The objective of this study was to estimate the seroprevalence of BT virus (BTV) in small ruminants of two eco-zones of Nepal, Hills and Terai, and to identify the factors associated with virus exposure. We conducted a cross-sectional serosurvey from March 2012 through February 2013 by sampling 318 small ruminants (184 sheep and 134 goats) from seven clusters (villages) of selected vulnerable communities of Chitwan (Terai) and Lamjung (Hills) Districts of Nepal.
  
  
  RESULTS
  Of the 318 serum sample tested, 27.9% [95% confidence interval (CI): 23.1- 33.2] were positive for BTV antibodies (25.0% sheep and 31.3% goats). Bivariate analysis indicated a positive association between seroconversion to BTV and flock size, eco-zone, breed, and contact history with cattle. Additionally, in female sheep and goats, a history of abortion was positively associated with seropositivity to BTV. However, the final multivariable model, after controlling for clustering of animals within the villages, identified only history of abortion and breed as the factors significantly associated with BT seropositivity in female sheep and goats. Based on this model, female small ruminants having a history of abortion were more likely to be seropositive compared to those without such history [Odds Ratio (OR) = 46.14 (95% CI: 11.66- 182.5)]. Exotic breeds were more likely to be seropositive compared to indigenous breeds [OR = 9.04 (95% CI: 3.08- 24.46)] while the risk for BTV seropositivity was not significantly different between indigenous and cross breeds.
  
  
  CONCLUSIONS
  Our results showed that nearly a quarter of small ruminants in two regions of Nepal were seropositive for BTV, indicating wide exposure of small ruminants to this pathogen. We identified history of abortion and breed as factors significantly associated with the seropositivity of BTV. We recommend that surveillance for BTV infection in Nepal be strengthened and that it would be valuable to enhance the education of farmers about the possible impacts of this disease.
authors.affiliation: Institute of Agriculture and Animal Science, Tribhuvan University, Chitwan, Nepal. sharma_tara16@yahoo.com.
authors.forename: Tara Nath
authors.initials: TN
authors.lastname: Gaire
authors.forename: Surendra
authors.initials: S
authors.lastname: Karki
authors.forename: Ishwari Prasad
authors.initials: IP
authors.lastname: Dhakal
authors.forename: Doj Raj
authors.initials: DR
authors.lastname: Khanal
authors.forename: Nanda Prakash
authors.initials: NP
authors.lastname: Joshi
authors.forename: Bishwas
authors.initials: B
authors.lastname: Sharma
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bowen
mesh_terms: D000034:Abortion, Veterinary; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001819:Bluetongue / Q000097:blood / Q000175:diagnosis / Q000635:transmission / Q000821:virology*; D001820:Bluetongue virus / Q000276:immunology / Q000302:isolation & purification*; D001947:Breeding; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015511:Goat Diseases / Q000097:blood / Q000175:diagnosis / Q000635:transmission / Q000821:virology*; D006041:Goats; D008297:Male; D015999:Multivariate Analysis; D009390:Nepal; D016017:Odds Ratio; D012307:Risk Factors; D012418:Ruminants / Q000382:microbiology*; D016036:Seroepidemiologic Studies; D012698:Serologic Tests; D012756:Sheep
chemical_list: D000914:Antibodies, Viral; D015415:Biomarkers