North Dakota Vetrinary Diagnostic Lab

West Nile Virus

West Nile Virus (WNV) infections have been detected in multiple North Dakota animal species this summer. The first case diagnosed at the NDSU-VDL was in a mule in early August.Since that time three horses have tested positive by WNV IgM capture ELISA with two additional horses having inconclusive results. A squirrel, duck, and gosling have also tested positive for WNV. Antemortem diagnosis using the IgM capture ELISA is the best test for acute disease in horses, with IgM titers rising 3-8 days after infection.Recent vaccination should not interfere with interpretation of results.  Post-mortem testing on brain (preferred sample) using PCR is also offered by the VDL.

NDSU-VDL strongly recommends WNV vaccination for horses to prevent the potentially devastating neurologic disease.  Reduction of mosquito numbers and avoiding exposure to mosquitos at peak feeding times (around sunset and sunrise) is also recommended. If using pesticide products, make sure they are safe/approved for use in veterinary species.