First human case of a mosquito-borne illness reported in Ottawa this year

Ottawa Public Health (OPH) officials are asking residents to be diligent when in areas with mosquitoes, as the agency reports the first case of human West Nile virus in the nation’s capital.

According to OPH, there is an Ottawa resident who has developed a West Nile virus infection, the first of the 2025 season.

In the province, there have been 11 human cases of West Nile virus, and last year in Ottawa, the agency reported 13 human cases.

This comes after the agency recently confirmed a horse tested positive for Eastern Equine Encephalitis virus (EEEV), another mosquito-borne illness. Spread to a human is historically rare, OPH said, with only four detected in the province.

“Although rare, the disease is of concern because, like WNV, it can cause a serious neurological disease and even death,” health officials said.

They are urging people to protect themselves from mosquito bites.

West Nile virus is an infection that can be spread by the northern house mosquito. In some cases, it can cause serious illness the release notes, others will have flu-like symptoms.

“The risk of more serious illness – occurring in less than one per cent of infections, in which WNV impacts the central nervous system – increases with age,” health experts said. “Older adults, the elderly and people with weakened immune systems are at higher risk.”

How to protect yourself:

• Applying a Health Canada-approved mosquito repellent containing DEET or icaridin to exposed skin and clothing
• Wearing light-coloured, tightly woven, loose-fitting clothing, such as long pants, a long-sleeved shirt, shoes and socks, to protect exposed skin
• Making sure all windows and doors in your home have screens that are in good condition
• Removing, or emptying once per week, standing-water sites around your home, such as bird baths, toys, flower-pot saucers, swimming-pool covers, old tires, wheelbarrows, buckets, and cans
• Keeping all openings to rain barrels covered