Ottawa Public Health (OPH) is warning residents about a “notable increase” in West Nile virus in the city as more mosquito trapping pools are testing positive for the virus than in past years.
Five of the pools — traps placed around the city to determine the species and density of the mosquito population — are currently testing positive for the virus, OPH said.
That’s the highest number of concurrently positive results since 2017, when seven pools tested positive at once.
A total of 14 testing pools have tested positive for West Nile virus at various times since the 2024 mosquito season began.
2 human cases reported to OPH
Two human cases of West Nile have been reported in Ottawa this year, the health unit said.
A recent release from OPH warns residents to cover up with loose-fitting clothing and recommends mosquito repellents.
OPH says people can also protect themselves by ensuring screens on windows and doors are in good condition, and by draining any standing water around their home at least once a week.
NEW: we are reminding residents to protect themselves against mosquito bites to reduce the risk from eastern equine encephalitis virus and West Nile virus.<br> <br>More info: <a href=”https://t.co/zIP0lueymf”>https://t.co/zIP0lueymf</a>
—@OttawaHealth
In addition to West Nile, the discovery of eastern equine encephalitis in a local horse is also causing concern.
That virus, also known as EEEV, is normally transmitted between birds and mosquitoes but can occasionally infect horses and, more rarely, humans through mosquito bites.
OPH says mosquitoes with that virus are normally found close to swampy hardwood forests. Only three human cases of EEEV have been detected in Ontario, most recently in 2022.
Although EEEV infections are rare, OPH warns that like West Nile, the virus can cause “a serious neurological disease and even death.”
Virus detected elsewhere
The Kingston, Ont., area’s health unit said it’s seen that region’s first probable case of the West Nile in a local resident, as well as in a crow.
Kingston, Frontenac and Lennox & Addington Public Health said while four out of five people infected with West Nile will experience no symptoms, some may develop a mild flu-like illness with a fever, headache and body aches that could last more than two weeks. Severe cases are more rare.
Last week, Renfrew County and District Health Unit also issued a news release stating the West Nile virus has been detected in mosquitos in Arnprior, Ont.
Hastings Prince Edward Public Health said it’s also found infected mosquitoes in the Belleville, Ont., area.