Ottawa Public Health Renews Mosquito Bite Warning as West Nile Virus Returns for the Season

Ottawa Public Health is renewing its seasonal call for residents to protect themselves against mosquito bites after confirming the first West Nile virus positive mosquito pools of the year, detected through the city’s routine summer surveillance program.
The positive samples were collected on July 26 as part of ongoing trapping and testing that Ottawa Public Health has carried out since June. No confirmed or probable human cases of West Nile virus have been reported in Ottawa so far this year, and only two human cases have been recorded across Ontario as of late July. Officials say the finding is not unexpected for this point in the summer and mainly serves as a reminder that the virus is now circulating locally.
West Nile virus spreads mainly through Culex pipiens mosquitoes, a species that thrives in urban settings, including neighbourhood parks, backyards and anywhere water tends to collect. Roughly eighty percent of people infected show no symptoms at all, while about one in five develop a mild flu like illness with fever, headache, body aches or a rash. Fewer than one percent go on to develop serious neurological complications such as meningitis or encephalitis, with older adults and people with weakened immune systems facing the highest risk of severe illness.
Ottawa Public Health recommends residents apply an approved insect repellent, wear loose fitting long sleeves and pants during peak mosquito hours at dawn and dusk, and keep window and door screens in good repair. The agency is also asking residents to reduce mosquito breeding sites around their homes by emptying standing water from flowerpots, buckets, birdbaths, toys and clogged eavestroughs, and by changing birdbath water at least once a week.
Health officials note that mosquitoes can pose a West Nile risk in the Ottawa area until the first hard frost of the fall, with most human cases in Ontario historically occurring in August and September. There is no human vaccine for West Nile virus, making personal prevention the primary line of defence during the coming weeks.