Update: West Nile Virus in Saskatchewan and Manitoba
It is that time of the year again! Since mid-July, the CCWHC Western-Northern has diagnosed West Nile virus (WNV) in five crows from Saskatchewan and in one Cooper’s hawk from Brandon, Manitoba. Clinical signs in these birds included neurologic abnormalities such as inability to fly/walk, incoordination dullness and sudden death. In all cases there were no obvious lesions seen during the autopsy; however, microscopic examination revealed inflammation of the brain and, in some cases, the heart. The virus was confirmed with molecular diagnostic tests.
West Nile virus was first introduced to North America in 1999, and since then it has become established throughout the United States and Canada. The virus has been documented in over 300 species of birds, but corvids (American crow, Back-billed Magpies, Blue Jays) and some raptors (merlins) are particularly susceptible and often die from infection.
The virus is transmitted via blood-feeding insects (ie. mosquitos) and can also infect humans. The majority of human cases are subclinical, but approximately 10% of infected individuals will develop flu-like symptoms. In very rare cases (0.1%) the virus can cause inflammation of the brain and death.
All corvids, and some raptors, submitted to the CCWHC Western-Northern lab will be tested for WNV until the mosquito season comes to an end. Updated test results are posted on the CCWHC website: http://www.ccwhc.ca/wnv_report_2013.php
For more information regarding WNV infection, see the Public Health Agency of Canada (http://www.phac-aspc.gc.ca/wn-no/gen-eng.php) or the Center for Disease Control and Prevention (http://www.cdc.gov/westnile/index.html)