Ottawa Public Health says there have been 13 reported cases of West Nile virus in people so far this year, and warns warmer than usual weather means mosquitos carrying the virus are still likely to be present in the city.
The mosquito-borne infection was expected to be more prominent this year after record rainfall in the spring and summer. In Ontario this year, as of September 16, there have been 98 reported human cases, compared with 55 last year, including just two in Ottawa.
The previous high number of cases for Ottawa was eight, in 2012.
Most people infected don't show any symptoms, but in one in five people experience flu-like symptoms, including fever, headache, muscle pain and rashes, according to Ottawa Public Health.
Urban areas more likely to have mosquitos in question
West Nile can also cause serious illness if the infection enters the central nervous system, but only in less than one per cent of infections.
The mosquitos most likely to spread the infection are found in urban areas in and around homes, Ottawa Public Health said.
"These mosquitoes will pose a risk on warm days until there have been several hard frosts," the agency said.
The City of Ottawa is urging people to protect themselves from mosquitoes by wearing bug spray at peak times — dusk and dawn — and removing standing water where they could breed.