Public health use of surveillance for West Nile virus in horses: Saskatchewan, 2003-2005.

West Nile virus (WNV) infection in horses was first reported in Canada in 2001 and in the province of Saskatchewan in 2002. This paper outlines the surveillance results of WNV in Saskatchewan horses from 2003 to 2005 and describes the usefulness of its inclusion in an integrated surveillance program in Saskatchewan. The number of human and horse cases was highest in 2003, the epidemic year and then substantially lower in 2004 and 2005. Horses provided additive information about WNV activity in rural areas with low human population, however, this required willingness and active participation by veterinarians and horse owners. Vaccination impedes the future use of horses in WNV surveillance for public health or veterinary purposes; however, for zoonoses where no vaccination is available, domestic animals would be useful components for surveillance. Integration of surveillance data from human and animal health provide the benefit of a more complex epidemiological picture that can be used to improve public health.