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Questions and Answers 
West Nile virus questions and answers
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Who is likely to get infected?
Birds and mammals can be infected by the virus, but members of the corvid family – crows and jays – seem to be the most susceptible and suffer high mortality. By comparison, the risk to humans of becoming seriously ill because of West Nile infection is low and most people who become infected experience no symptoms or have very mild illness. In less than one per cent of human cases there are serious medical implications from West Nile infection. Current medical information about symptoms and appropriate responses
 
Pets can contract WNV from a mosquito bite, but the risk of becoming seriously ill is very low and full recovery is likely.
How is WNV spread?
Mosquitoes become infected with the virus when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals when they bite. It cannot be transmitted through regular human contact or retransmitted to biting mosquitoes.
 
A very small portion of infection can occur through blood transfusions or organ transplants, and in rare cases from breastfeeding and during pregnancy.
 
It is not spread by person-to-person contact and is not known to be transmitted from mammals, such as horses, to humans. An equine vaccination for WNV is available. Refer to the BC Centre for Disease Control for current scientific information about virus transmission and infection cycles.
What are the symptoms of WNV?
The majority of people who get infected with WNV have no symptoms and are not at risk for health problems. Others experience mild flu-like symptoms. Less than one per cent of people infected with WNV will develop a serious illness. The overall risk for serious illness increases with age. If illness occurs it usually happens five to 15 days after being bitten by an infected mosquito. Refer to regional health authorities for a list of symptoms and the appropriate responses.
What is the treatment for WNV?
There is no medication or cure for WNV, but many of the symptoms of the disease can be treated. Most people who are infected make a full recovery. There is no vaccine at this time.
Has anyone in Canada ever died from WNV?
In 2007, the worse year for human infections in Canada, there were about 2,300 human cases (including 10 deaths), the vast majority occurring in the Prairie provinces. In B.C., there were 19 travel-related cases, even though no one contracted WNV in B.C. Consider taking precautions when traveling to locations where WNV is prevalent, such as Canada’s Prairie provinces. 
Should I be worried if a mosquito bites me?
No. Of the approximately 50 species of mosquitoes known in B.C., three are important carriers of WNV. These three species show a preference for breeding in stagnant or polluted water. If you are conscientious about removing standing water from your property and encouraging mosquito predators like swallows and bats, you will have reduced your chances of exposure to an infected mosquito.
How can bird deaths help to identify WNV in an area?
Several species of mosquito and many species of birds can become infected with WNV during the cycle of transmission; members of the crow family (crows, ravens, magpies and Stellar's jays) are particularly sensitive to the virus and have high death rates if infected. Evidence from the United States suggests that crow die-offs precede an increased risk for human illness by two to six weeks. Monitoring of dead crows can provide an early warning signal that WNV is moving into an area.
What can I do if spot a dead bird?
A fixed number of birds from each health authority will be tested for WNV as part of a provincial program of bird testing. If you find a dead crow, contact your local health authority or report online to find out if they need to test the bird for infection. If the bird is on Metro Vancouver property, notify a Metro Vancouver park officer or other staff member.

Resources

Regional health authorities test dead corvids during mosquito season (May to September) to help determine the virus's spread.

 Report dead corvids online

Fast Facts

Catch basins are drains – the ones with grates beside the curb. Health authorities and local municipalities are working together to identify, monitor and implement appropriate mosquito control measures in these structures. Individual residents are encouraged to participate by ensuring that drains in yards and driveways are clean and contain no debris.