Mosquitoes test positive for West Nile Virus

(The common northern house mosquito. Photo: Flickr)

Mosquito trapping and testing-components of Ottawa Public Health’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.

An infection spread primarily by the northern house mosquito, West Nile Virus (WNV) can cause serious illness in a small number of cases. 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. A more serious illness whereby WNV invades the central nervous system – occurring in less than one per cent of infections – increases the risk with age, in older adults, the elderly and people with weakened immune systems.

There have been no reported, confirmed or probable human cases of West Nile Virus in Ottawa this year. As of Wednesday, August 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.

The Chief Medical Officer for Ottawa Public Health, Dr. Vera Etches, said, “Spending time outdoors has many health benefits. 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.”

Protect yourself and family members 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

Ottawa Public Health 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


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