Ottawa Public Health says a mosquito pool in Ottawa has tested positive for West Nile virus.
This is the first confirmation this year since OPH began routine seasonal monitoring in June, according to a public service announcement on Friday.
While there have been no confirmed or probable cases of the virus reported in Ottawa this year, as of July 26, there have been two reported human cases in Ontario, according to the PSA.
In 2025, OPH confirmed at least one case of the virus in a human in Ottawa.
What is West Nile virus?
This is an infection spread by the northern house mosquito, where less than one per cent of infections lead to very serious illness, according to OPH.
Most people bitten by an infected mosquito will not develop any symptoms, “but about 20 per cent will experience flu-like symptoms such as a fever, headache, muscle aches and possibly a rash, that usually appears two to fourteen days after being bitten.”
How can I protect myself?
OPH offers guidance for Ottawa residents in protecting themselves against WNV.
- Apply an approved mosquito repellent to exposed skin and clothing.
- Wear long pants, a long-sleeved shirt, shoes and socks to protect exposed skin.
- Wear light coloured, tightly woven clothing but loose-fitting clothing as mosquitoes are attracted to darker colours and can still bite through thin clothing.
- Avoid the hours between dusk and dawn — periods when mosquitoes are most active — and at any time in shady, wooded areas. Take extra care to use repellent and protective clothing from dusk to dawn or consider avoiding outdoor activities during these times.
- Make sure all windows and doors in your home have well-fitting screens that are in good condition.
