West Nile Virus (WNV) belongs to a family of viruses called Flaviviridae and is closely related to the viruses that cause Dengue Fever, Yellow Fever and St. Louis Encephalitis.
WNV is spread by mosquitoes that have fed on the blood of infected birds. Most people infected with the virus have no symptoms or mild symptoms like the flu. However, individuals with weaker immune systems and chronic diseases are at greater risk for serious health effects.
The virus originated in the West Nile Valley region of Uganda in 1937. Since the first North American outbreak of WNV in 1999 in New York City, all lower 48 states and 8 Canadian provinces have confirmed human WNV cases. The first confirmation of WNV contracted in BC occurred in the summer of 2009. On August 22, 2009, a mosquito pool sample in the South Okanagan tested positive for the virus and within the week two Kelowna residents were confirmed to have been infected by the virus. Two weeks later, one horse in Aldergrove, along with two horses in Osoyoos, were tested and positive for the virus.
Although the virus is not known to be transmitted to humans from other animals, people should avoid handling dead animals or birds with their bare hands. WNV virus has been found in more than 150 bird species in North America. Some species may have no obvious signs of illness when infected. Others, such as those of the Corvid family (crows, jays, magpies and ravens) get sick more often and can die.
Birds of the Raptor family have also died off in significant numbers in areas of Ontario in past years for example. Horse owners in B.C. are encouraged to talk to their veterinarians about the vaccine that is available to protect their animals.
Disease surveillance in Canada mostly takes place in the summer months when mosquito populations are at their highest. The incidence of WNV fluctuates annually across provinces, but people should continue to take a common sense approach for personal protection. Since mosquitoes do not fly very far from their breeding sites, you are most likely to be bitten by a mosquito in your own backyard. Clean up areas where mosquitoes like to breed or rest. It can take only one week of water build up for mosquitoes to develop from eggs into adults. So be sure to remove any type of standing water on your property at least once a week.
Found a dead bird?
Here is information on how to dispose of dead birds as specimen pick-up is limited.
For more information, visit the British Columbia Centre for Disease Control for current information on the status of WNV under 'Health topics A-Z' and in the 'W' section for 'West Nile Virus' information.
Or, contact your local health authority:
Fraser Health Authority or call: 1-888-WNV-LINE (968-5463)
Vancouver Island Health Authority or call: 1-866-WNV-VIHA (968-8442)
Interior Health Authority or call: 1-866-300-0520
Northern Health Authority