TORONTO, July 17, 2026 – As summer temperatures rise and mosquito activity increases, Toronto Public Health has confirmed that mosquito samples collected in the city have tested positive for West Nile virus for the first time this year.
According to a City of Toronto update released on July 17, a batch of mosquitoes collected through the city’s monitoring program was confirmed to be carrying West Nile virus. This marks Toronto’s first detection of West Nile virus-positive mosquitoes in 2026. However, public health officials continue to consider the overall risk of residents becoming infected in Toronto to be low.
Residents should note that detecting infected mosquitoes does not mean Toronto has recorded its first human case of West Nile virus this year. The results come from the city’s routine mosquito surveillance program, which is designed to track virus activity among local mosquito populations and remind residents to take preventive measures.
Toronto Public Health conducts mosquito surveillance every year from mid-June to mid-September. Each week, 22 mosquito traps are placed across the city to collect samples, which are then sent to laboratories for species identification and virus testing.
West Nile virus is primarily transmitted through the bite of an infected mosquito. If symptoms occur, they usually appear between two and 14 days after a bite and may include fever, headache, body aches, nausea, vomiting, rash, and swollen lymph nodes. Adults aged 50 and older, as well as people with weakened immune systems, face a relatively higher risk of developing severe illness.
For Chinese seniors and caregivers, extra attention should be paid during summer, especially during early morning and evening hours when mosquitoes are more active. Residents spending extended periods outdoors can wear light-coloured long sleeves and pants, and use Health Canada-approved insect repellents according to instructions.
Standing water around homes is another commonly overlooked risk. Toronto Public Health warns that small amounts of water collected in pool covers, flower pots, buckets, children’s toys, and garbage containers can provide breeding areas for mosquitoes. Residents should regularly check yards, balconies, and areas around their homes, and remove unnecessary standing water.
Residents should also repair damaged window and door screens as soon as possible to reduce the chance of mosquitoes entering their homes.
Toronto has not increased the overall public health risk level following the detection of these positive mosquito samples, but monitoring will continue throughout the summer. As temperatures rise and outdoor activities increase, mosquito prevention will remain important in the coming months.
Public health officials advise residents who develop concerning symptoms after mosquito bites to contact a healthcare professional. For most people, there is no need to panic because of the detection of infected mosquitoes, but removing standing water and taking personal protection measures remain the most effective ways to reduce infection risk.(LJI by Yuanyuan)
