Epidemiology and Infection

Environmental and ecological determinants of West Nile virus occurrence in horses in North Dakota, 2002

M. NDIVA MONGOH a1, M. L. KHAITSA a2c1 and N. W. DYER a3
a1 Natural Resources Management Program, College of Agriculture, Food Systems, and Natural Resources (CAFSNR), North Dakota State University, Fargo, ND, USA
a2 Department of Veterinary and Microbiological Sciences, CAFSNR, North Dakota State University, Fargo, ND, USA
a3 Department of Veterinary Diagnostic Services, CAFSNR, North Dakota State University, Fargo, ND, USA

Article author query
mongoh mn   [PubMed][Google Scholar] 
khaitsa ml   [PubMed][Google Scholar] 
dyer nw   [PubMed][Google Scholar] 


West Nile virus (WNV) outbreak in North Dakota in 2002 included over 569 horse cases, clustered mainly in the eastern and northeastern parts of the state. The pattern of occurrence observed suggested existence of specific environmental and ecological factors that increased the risk for infection and illness in those locations. We developed a predictive model with factors that explained the pattern of WNV occurrence observed. Results indicated that surface elevation, temperature, precipitation, reported WNV-positive birds, reported WNV-positive humans, and reported WNV-positive mosquitoes were important predictors of occurrence in horses. However, case distance from water bodies was not significant in the model. Future predictive models of WNV occurrence in horses should take into account these factors in order to improve accuracy and reliability. Research into other potential determinants such as horse management factors are required to determine more differential risk factors associated with WNV occurrence in horses.

(Accepted April 3 2006)
(Published Online June 6 2006)

c1 1523 Centennial Blvd, Fargo, ND 58105-5406, USA. (Email: Margaret.Khaitsa@ndsu.edu)