West Nile Virus found in Alberta

Aug 25 2004

Alberta's first West Nile virus positive bird of the 2004 season has been detected in Lethbridge. A mosquito pool and a horse in Southern Alberta have also tested positive for the virus.

The infected crow was detected through the province's wild bird surveillance program. In total, 550 birds were tested before the positive case was found.

The infected Culex tarsalis mosquitoes were found in the Vulcan area. Culex tarsalis is the one species of more than 40 types of mosquito in the province known to transmit West Nile virus.

Most people bitten by an infected mosquito will show no symptoms, but one in five will develop West Nile fever, which can result in severe headache, chills, body aches and fever, often requiring extended bed rest.

A small number of individuals will experience the more severe symptoms of West Nile Neurological Syndrome. As a result, it is important for Albertans to protect themselves from mosquito bites (see sidebar).

Horse owners can minimize their animals' exposure to mosquito bites through the use of insect repellents, screened housing, smudges and eliminating standing water in which mosquitoes breed. West Nile virus vaccines for horses are available in Canada through veterinarians.

Evidence of the virus has been scarce this summer, and numbers of Culex tarsalis are low, likely due to cooler weather this summer. But with evidence of the virus now appearing, and with humans cases now reported in Saskatchewan, health officials are advising Albertans, especially in the southern areas of the province, to continue taking precautions to avoid mosquito bites until the first local, hard frost.

The government provided funding this year for municipalities to help reduce Culex tarsalis numbers, based on the areas of the province at greatest risk.