West Nile is common in the species of mosquitos that feed on birds. As a result, any dead bird, such as a magpie, crow or bluejay, must be tested to see if has died from exposure to West Nile virus.
Bird Watch -- Mosquitoes get the virus through feeding on infected birds and then transmit the virus to humans through mosquito bites. Not all of the 74 species of mosquitoes in Canada carry WN virus, but it is more common in species that feed on birds. The virus has been found in more than 150 bird species in North America. Some species may have no obvious signs of illness when infected. The most susceptible birds are crows, blue jays, gray jays, magpies and ravens.
Keep an eye out for dead birds in your community. If you see anything unusual- especially dead crows, ravens, jays or magpies- contact your local or provincial health authority. Information on dead bird surveillance in Canada is tracked by the Canadian Cooperative Wildlife Health Centre. The Canadian Food Inspection Agency will monitor WN virus in animals other than birds, with a particular focus on horses.
It takes about two weeks before the mosquito is capable of transmitting the virus to a human or animal. There is some evidence that female mosquitoes may be able to transfer WN virus to their offspring, but researchers are still looking into this possibility.