I stood at the edge of a local pond in Waterloo Region last Wednesday, watching a family of ducks glide across the water’s surface. The late-summer scene was picturesque, but the small clouds of mosquitoes hovering near the shoreline served as a subtle reminder of the season’s hidden risks. Just days later, public health officials confirmed what many had been anticipating: the region’s first human case of West Nile virus this year.
“We’ve been monitoring mosquito pools since June,” Dr. Hsiu-Li Wang, Medical Officer of Health for the Region of Waterloo, told me during our phone conversation yesterday. “Finding a human case isn’t unexpected, but it’s an important reminder that the virus remains active in our community.”
The affected resident, whose identity remains confidential for privacy reasons, has been receiving medical care. Officials would not disclose the severity of symptoms or the specific location within the region where the person might have contracted the virus.
West Nile virus first appeared in Canada in 2001, gradually establishing itself as part of our seasonal public health landscape. The virus typically circulates between birds and mosquitoes, with humans becoming incidental hosts when bitten by infected mosquitoes. According to Public Health Ontario’s most recent surveillance report, the province has documented 14 human cases this season prior to this Waterloo Region case.
“Most people infected with West Nile virus won’t develop any symptoms at all,” explains Dr. Wang. “About 20 percent experience mild symptoms like fever, headache, body aches, or a rash. In rare cases—less than one percent—the virus can cause severe neurological illness.”
This reality is something Colin McKenzie, a 67-year-old Cambridge resident, knows firsthand. In 2018, he spent three weeks in hospital with West Nile neuroinvasive disease, experiencing debilitating headaches and temporary paralysis.
“I never thought a mosquito bite could change my life,” McKenzie shared while we talked in his garden, a space he’s redesigned to minimize standing water. “Even after recovery, I had lingering fatigue for almost a year. People don’t realize how serious it can be.”
For public health officials, the challenge lies in balancing awareness without causing undue alarm. The Region of Waterloo Public Health has been conducting mosquito surveillance throughout the summer, testing trapped mosquitoes for the virus. Several positive mosquito pools were identified in July and August before this human case emerged.
The timing aligns with typical seasonal patterns. Late summer and early fall represent the period of highest risk for West Nile transmission in southern Ontario. The combination of warm temperatures and accumulated standing water creates ideal conditions for both mosquito breeding and viral replication within the insects.
Dr. Manisha Kulkarni, an associate professor at the University of Ottawa who studies vector-borne diseases, points to climate change as a factor potentially extending the transmission season.
“We’re seeing longer periods of warm weather, which can expand the window during which mosquitoes remain active,” she explains. “Models suggest that parts of Canada, including southern Ontario, may experience increased West Nile risk as climate patterns shift.”
While the public health response to West Nile includes surveillance and education, much of the prevention burden falls on individuals. The Region of Waterloo Public Health emphasizes what they call the “4 Ds” of prevention: Drain standing water, Dress in light-colored clothing that covers exposed skin, Defend yourself with insect repellent containing DEET or icaridin, and avoid outdoor activities during Dawn and Dusk when mosquitoes are most active.
Walking through Victoria Park in Kitchener yesterday evening, I noticed several people in shorts and t-shirts despite the mosquitoes buzzing near the pond. When I mentioned West Nile virus to a young couple with a toddler, they seemed surprised it was present locally.
“We use bug spray, but mostly just to avoid itchy bites,” said Sarah Khamis, bouncing her daughter on her hip. “I didn’t realize we needed to worry about West Nile here.”
This knowledge gap highlights the ongoing challenge for public health communicators. The virus has become endemic to our region, yet awareness ebbs and flows with media coverage and reported cases.
For vulnerable populations, the risk is more significant. Adults over 50, those with compromised immune systems, and people with certain chronic medical conditions face higher risks of severe illness if infected. Health Canada data shows that while severe cases remain rare, they disproportionately affect these groups.
Linda Brookes, who runs a seniors’ walking group in Waterloo, has incorporated mosquito awareness into their activities. “We schedule our walks for mid-morning, avoid paths near standing water, and I always bring extra repellent,” she explains. “Most of our members remember when West Nile first came to Canada, so they take it seriously.”
As fall approaches, the risk will naturally diminish with cooling temperatures. However, public health officials caution that mosquito activity continues until the first hard frost, which typically occurs in late October or early November in Waterloo Region.
The confirmed human case serves as a reminder that despite being a predictable seasonal concern, West Nile virus requires continued vigilance. The virus has become part of our environmental reality—one more consideration in how we interact with our outdoor spaces during the warmer months.
Standing again by that same pond days after the announcement, I noticed something different. A municipal worker was posting a small sign warning about mosquitoes and West Nile risk. It was a subtle change to the landscape, but a visible reminder that our relationship with nature carries both beauty and risk—a balance we negotiate each time we step outside during mosquito season.
