In Canada’s warmer-than-usual summer in 2025, some homeowners stayed busy with outdoor tasks. However, this also provided mosquitoes with an extended period to prey on unsuspecting humans.
Ontario resident René van den Berg spent 11 days in the hospital after contracting the West Nile virus (WNV) in September, CTV News reported. Experts warn that rising global temperatures can accelerate breeding cycles and increase mosquito days, heightening the risk of getting the virus.
What happened?
Van den Berg spoke with the outlet while recovering at home, saying, “I thought mosquitoes would die off at the end of August, when temperatures get colder at night.”
The backyard, where he suspected he got the bite, also didn’t have stagnant water, a common breeding ground for mosquitoes.
After the headaches he first experienced on September 20 became unbearable, he sought medical help and was later diagnosed with viral meningitis due to WNV.
WNV symptoms typically show up two to 15 days after a mosquito bite, according to the Region of Waterloo Public Health. Debilitating conditions, such as those Van den Berg went through, affect less than 1% of people infected with WNV.
Why is this concerning?
The government of Canada’s latest mosquito-borne disease surveillance lists 239 human cases of West Nile virus. Of these, the highest number of cases — 149 — were from Ontario.
West Nile virus can cause muscle aches, mild fever, and skin rash. In some cases, it can be deadly — especially for older adults and immunocompromised individuals.
According to a government surveillance report, the country’s last reported WNV-related deaths were two people over age 70 in 2023.
In the U.S., senior citizens also died of WNV in Utah and Texas, besides one death due to underlying medical conditions in Wayne, Michigan, according to CBS News.
Continued warm temperatures have stretched the life cycle of mosquitoes nationwide, Bernadette Moussa, acting manager at Region of Waterloo Public Health, told CTV News.
Scientists attribute this extreme weather event to a massive heatwave in the northern Pacific Ocean, triggered by rising global temperatures, according to CBC.
What’s being done about it?
Canadian news media show that health officials issued alerts immediately after confirmed cases in Toronto, Halton, and Huron Perth.
Toronto General Hospital infectious diseases specialist Dr. Isaac Bogoch told CTV News, “Make sure that people are aware that it’s circulating at certain times of the year and then taking steps to avoid and prevent mosquito bites to prevent transmission of this infection.”
Meanwhile, Region of Waterloo Public Health shared simple ways to protect yourself, including applying repellent and wearing long-sleeved tops and pants when outside, especially at dusk and dawn. Practice self-care by consulting a doctor to avoid serious complications.
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