A rare and deadly mosquito-borne illness, the eastern equine encephalitis virus (EEEV), has claimed the life of an Ottawa resident, marking the city’s first confirmed human case.
Ottawa Public Health (OPH) issued a warning Thursday, urging residents to protect themselves from mosquito bites to reduce the risk of contracting both EEEV and West Nile Virus, which are both spread by the insect.
“OPH has received laboratory confirmation that an Ottawa resident who died of viral encephalitis in August 2024 tested positive for eastern equine encephalitis virus infection,” the statement read.
This is the first confirmed human case of EEEV in Ottawa; however, it is important to note the virus is not a reportable disease in Ontario, the statement added. That means there’s no obligation to report and track cases among provincial health officials.
The EEE virus is transmitted through the bite of an infected mosquito.
While humans and certain mammals, such as horses and llamas, can contract the disease, they do not transmit it further. There are no human vaccines or treatments for the virus.
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The virus can also cause severe illness and potentially be fatal in any age group, with those under 15 and over 50 being particularly at risk, health officials warned. And while human cases are rare, the disease is of concern because it can cause serious neurological disease, OPH said.
The death rate stands between 30 and 70 per cent.
The best way to protect yourself from mosquito-borne viruses is to avoid getting bitten, OPH advised.
Mosquitoes remain active in both urban and rural areas at this time of year and will continue to pose a risk until heavy frosts later this fall, the health unit said. Residents can take the following steps to protect themselves from mosquito bites:
- Applying a Health Canada-approved mosquito repellent containing DEET or icaridin to exposed skin and clothing (avoid applying DEET to synthetic fabrics).
- Protecting yourself when mosquitoes are active, especially between dusk and dawn and any time you are near shady hedges or 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.
Last month, a town in Massachusetts closed its parks, playgrounds and sports fields from dusk to dawn due to the increased risk of EEEV in the region. Plymouth, located about 60 km south of Boston, announced these closures on Aug. 23 in response to a high risk of virus.
In Canada, human infections with EEEV have been rare.
Although national data is unavailable, Ontario had reported three human infections of the virus before this recent case in Ottawa.
On Aug. 21, Ottawa Public Health reported that a horse in Ottawa tested positive for EEEV and issued a warning.
The first detection of the virus in Canadian mosquitoes happened in September 2009, when a positive pool of mosquitoes was found in the First Nations Community of Wahta Mohawk, Ont., according to Public Health Ontario.
In Canada, EEEV infections mainly occur in the spring and are linked to birds migrating from the southern United States to northern Canada, according to Health Canada.