West Nile Virus

Fight the Bite Logo from Idaho Department of Health and Welfare


West Nile Virus (WNV) is a disease transmitted by mosquitoes and may be passed to humans, horses and occasionally camelids, such as llamas and alpacas, from a single bite. In horses, predominantly, it causes fever and neurologic symptoms such as hindlimb weakness or paralysis, uncoordinated gait and stumbling, as well as facial tremors and twitching. The summer of 2012 has been a particularly bad year for West Nile due to the dry, hot conditions causing mosquito populations to explode. Multiple West Nile cases in humans and horses have been reported in Idaho this summer and people are strongly encouraged to vaccinate their horses and take precautions to control the mosquito populations in their area.

testing of horses is offered by the ISDA Animal Health Laboratory through licensed veterinarians. For information on WNV in humans, horses, or other animals please visit the Department of Health and Welfare, USDA APHIS Veterinary Services, or our FAQ page*.

~ If you have questions about WNV in Humans please contact your local District Health Department.

~ If you have questions about WNV in Wild Birds please contact the Idaho Department of Fish and Game at (208) 454-7646.

~If you have questions about WNV in Horses please contact your veterinarian.

~ If you have questions about WNV in Multiple Species please refer to the National Wildlife Health Center.

~ If you have questions about WNV in relation to Pesticides please refer to Urban Pest Management under the Department of Agriculture.

Please remember to vaccinate your horses for their protection against West Nile Virus. Contact your veterinarian for vaccination recommendations.
Resources for veterinarians:

Neurological Checklist*

CSU Paper on Colorado and Nebraska Equine Cases - 2002*

*This document is in .pdf format.