Risks of West Nile virus

Find out what the risks of West Nile virus are and who is most at risk.

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

West Nile virus infection can lead to serious disease.

In most parts of Canada, the risk of becoming infected with West Nile virus starts mid-April. It goes to the first hard frost in late September or October. Humans are most at risk between mid-July and early September. Mosquitoes are often most active at dawn (first light) and dusk (just before dark).

Some people are at greater risk for serious health effects from West Nile virus. These include people:

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

Canada tracks West Nile virus with the help of its partners. For information about current statistics, please see the surveillance section.