First mosquitoes test positive for West Nile virus

OTTAWA – Ottawa Public Health (OPH) is reporting the first case of the West Nile virus found in a mosquito today (Aug. 11).

“OPH reminds residents to protect themselves from mosquito bites,” OPH staff released in a statement today. “Mosquito trapping and testing-components of OPH’s West Nile virus program-have confirmed the presence of the virus in Ottawa. Residents must also help reduce mosquito populations around their homes by getting rid of all outdoor objects that can hold water, where mosquitoes lay eggs.”

West Nile virus is an infection spread primarily by the northern house mosquito that, in a small number of cases, can cause serious illness. Most people will not develop any symptoms if infected, but about 20 per cent may experience flu-like symptoms, including a fever, headache, muscle aches and, possibly, a rash. The risk of more serious illness – occurring in less than one per cent of infections in which the West Nile virus invades the central nervous system – increases with age, with older adults, the elderly and people with weakened immune systems at higher risk.

“There have been no reported, confirmed or probable human cases of West Nile virus in Ottawa this year,” the OPH said. “As of Wednesday, Aug. 5, there have been zero reported human cases in Ontario this year.”

In 2019, there was one human case reported in Ottawa, and 24 cases in Ontario.

Protect yourself and your family from mosquito bites by:

Applying a Health Canada-approved mosquito repellent containing DEET or icaridin to exposed skin and clothing

Protecting yourself especially between dusk and dawn, when mosquitoes are most active, and at all times in or near shady, bushy or wooded areas

Wearing light-coloured, tightly woven, loose-fitting clothing, including 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

Reducing standing water sites around your home, such as bird baths, toys, flower pot saucers, swimming pool covers, old tires, wheelbarrows, buckets and cans – anything that can hold water for seven days or longer.

Keeping all openings to rain barrels covered with screen mesh at all times

“Spending time outdoors has many health benefits,” OPH Chief medical officer of health Dr. Very Etches said. “Due to the COVID-19 pandemic, more people are spending time outdoors in urban settings, including on their porches, in their gardens, and in local parks. These settings are ideal for the mosquitoes that transmit West Nile virus. Be sure to protect yourself against mosquito bites around your home.”

OPH has a proactive plan to deal with West Nile virus that includes weekly surveillance and, when necessary, mosquito larvicidal treatment of standing water on city property, such as ditches and storm water management ponds. Ottawa Public Health also regularly applies larvicide in city-owned roadside storm sewer catch-basins to reduce the mosquito population.

For more information on West Nile virus, visit or call Ottawa Public Health at 613-580-6744 (TTY: 613-580-9656).