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West Nile virus

West Nile virus (WNv) is a disease caused by the virus with the same name. It is spread to humans by mosquitoes that have fed on the blood of infected birds. Many people infected with West Nile virus have mild or no symptoms. People with weaker immune systems and people with chronic diseases are at greater risk for serious health effects from WNv such as meningitis, encephalitis and acute flaccid paralysis.

The Simcoe Muskoka District Health Unit conducts surveillance for WNv in our area by testing mosquito larvae and adults. For more information about these surveillance activities, visit the surveillance page of the WNv section of the Health Unit's website.

West Nile virus is a rare disease both locally and provincially. There are between zero and one confirmed and probable case in Simcoe Muskoka between 2002 and 2010.

The first year of disease activity in Ontario was 2002 with almost 400 cases. The number of cases declined significantly in Ontario in subsequent years.