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West Nile Virus (WNV) is a mosquito-borne virus that can cause swelling and inflammation of the brain and spinal cord in horses, birds and humans. Only specific species of mosquitoes spread WNV. In Alberta, the species of mosquito of 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.
- See also: West Nile Virus and wildlife
Only domestic geese, horses, mules and donkeys appear to be severely affected by WNV, and may develop clinical disease. Preventive measures should be discussed with your local veterinarian.
- See WNV symptoms, treatment and prevention in livestock: West Nile Virus fact sheet
How to report
If you suspect WNV in your livestock, call your veterinarian within 24 hours.
WNV is a provincially notifiable disease for horses, donkeys and mules and must be monitored.
All suspected or confirmed cases must be reported to the Office of the Chief Provincial Veterinarian (OCPV) within 24 hours:
Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-0000 before the phone number (in Alberta)
After business hours: 1-800-524-0051
WNV in horses surveillance
Table 1. Cases of WNV in Alberta horses (2003 to 2016)
|Year||Number of confirmed positive cases||Number of possible cases||Number of reactor cases||Number of suspect cases|
Figure 1. Case Distributions for 2018
This map shows the locations of 71 cases for which submission forms have been received.
View larger map (JPG, 481 KB)
Figure 2 . Case definitions for WNV
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