Part of Animal diseases

West Nile Virus in livestock

This mosquito-borne virus can cause swelling and inflammation of the brain and spinal cord in horses, birds and humans.


West Nile Virus (WNV) is a mosquito-borne virus that can cause swelling and inflammation of the brain and spinal cord in equids, such as horses, donkeys, mules, and zebras, as well as birds and humans. Only specific species of mosquitoes spread WNV. At present in Alberta, the species of mosquito of greatest concern is Culex tarsalis, which becomes infected when feeding on infected wild birds. Wild birds are the primary reservoir of WNV. Most wild birds are not affected by the virus, but rather just carry the virus for a variable period of time.

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Only equids and some domestic geese and ducks appear to be severely affected with clinical infection from WNV. Preventive measures should be discussed with your local veterinarian.

How to report

All suspected or confirmed cases of WNV must be reported to the Office of the Chief Provincial Veterinarian (OCPV) within 24 hours.

WNV is a provincially notifiable disease for horses, donkeys and mules and must be monitored. Statistics on cases are available at the provincially notifiable disease link or through the Canadian Animal Health Surveillance System.

Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Phone: 780-427-3448
Toll free: 310-0000 before the phone number (in Alberta)
Fax: 780-415-0810


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