West Nile virus

Risks

What are the risks of being infected with West Nile virus?

Because West Nile virus infection can lead to serious disease, it is important to learn more about it, what the risks are, and what can be done to reduce these risks.

In most parts of Canada, the risk of becoming infected with West Nile virus is greatest between mid-April and the first hard frost in late September or October. Most human infections occur between mid-July and early September. Remember that mosquitoes are often most active at dawn (first light) and dusk (just before dark).

People at higher risk for serious health effects from West Nile virus include:

• people over the age of 50
• those with chronic diseases, such as cancer, diabetes, alcoholism or heart disease
• those who require medical treatment that may weaken their immune system, such as chemotherapy for cancer

The Public Health Agency of Canada tracks West Nile virus in Canada with the help of its partners. For information about current statistics, please see the Surveillance page.