Ottawa Public Health reports first human case of West Nile virus in city this year

In this Aug. 16, 2012, file photo, mosquitos are sorted at the Dallas County mosquito lab in Dallas, TX. (AP Photo/LM Otero, File)

Ottawa Public Health (OPH) says West Nile virus has been detected in the local mosquito population and one person in the city has a confirmed case.

In a news release Friday evening, OPH said mosquito trapping and testing have confirmed the first positive mosquito testing pool of the annual monitoring season, which began June 1.

The confirmed human infection is the first of the year. Last year, there were no lab-confirmed cases of West Nile virus in Ottawa. There were 54 confirmed cases across Ontario in 2023.

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"West Nile virus is an infection spread primarily by the northern house mosquito (Culex pipiens) that, in a small number of cases, can cause serious illness," OPH says. "Most people will not develop any symptoms if infected, but about 20 per cent may experience flu-like symptoms, including 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 WNV impacts the central nervous system — increases with age, with older adults, the elderly, and people with weakened immune systems being at higher risk."

The health unit is advising residents to take precautions to protect themselves from mosquito bites and prevent mosquito breeding, using the following tips:

• 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 any time you are near shady, bushy, or wooded areas
• 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 with screen mesh at all times

OPH says its plan to help reduce the risk of West Nile virus includes weekly surveillance and mosquito larvicidal treatment of natural and human-made standing-water sites on City property, like ditches and stormwater management ponds.

"As part of this plan, Ottawa Public Health regularly applies larvicide in City-owned stormwater management ponds, roadside storm-sewer catch basins and private catch basins (by request) to reduce the mosquito population."