News Release
July 23, 2021

Today, Toronto Public Health (TPH) received confirmation of two mosquito pools in the city  that have tested positive for West Nile virus (WNV). These are the first positive pool tests for WNV in Toronto this year.

WNV is an infection transmitted to people through the bite of an infected mosquito. TPH conducts mosquito surveillance from mid-June until mid-September every year. Once a week, 22 mosquito traps are set across the city to collect mosquitoes and submit to a laboratory for identification of WNV. In 2020, a total of 39 positive mosquito pools were reported.

While the risk of getting infected in Toronto is currently low, TPH advises residents to take these precautions to avoid bites from infected mosquitoes:

  • Wear light-coloured clothing, long pants and long-sleeved shirts when outdoors.
  • Apply insect repellent containing DEET or icaridin and follow the manufacturer’s instructions.
  • Take extra care during peak mosquito-biting hours, dusk and dawn, by using repellent and covering up.
    Make sure your home has tight-fitting screens on windows and doors.
  • Remove standing water from your property, where mosquitoes can breed. Standing water includes any water that collects in items such as pool covers, buckets, planters, toys and waste containers.

WNV symptoms usually develop between two and 14 days after a person is bitten by an infected mosquito. Symptoms may include fever, headache, nausea, vomiting, body aches, skin rash and swollen lymph glands. Older individuals or individuals with compromised immune systems are at higher risk of severe illness. A person who has concerns about any symptoms should contact their health care provider.

More information is available here


“The risk of becoming infected with West Nile virus continues to be low in Toronto, however we’re taking this opportunity to share some simple steps residents can take to further reduce their potential risk when enjoying the outdoors this summer. These steps include wearing insect repellent and light coloured clothing to protect themselves from infected mosquito bites.”
– Dr. Eileen de Villa, Toronto’s Medical Officer of Health

Toronto is home to more than 2.9 million people whose diversity and experiences make this great city Canada’s leading economic engine and one of the world’s most diverse and livable cities. As the fourth largest city in North America, Toronto is a global leader in technology, finance, film, music, culture and innovation, and consistently places at the top of international rankings due to investments championed by its government, residents and businesses. For more information visit the City’s website or follow us on Twitter, Instagram or Facebook.

Media contact: Toronto Public Health Media Relations,