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Aug 222 min read

Ottawa Public Health encourages residents to protect themselves from mosquitoes as eastern equine encephalitis virus is confirmed in a local horse




Ottawa Public Health (OPH) is recommending that residents protect themselves against mosquito bites to reduce the risk from eastern equine encephalitis virus (EEEV) and West Nile virus (WNV). A horse in Ottawa has recently tested positive for EEEV and OPH’s West Nile virus prevention program has confirmed two human cases of WNV this season. Both diseases spread to humans through mosquito bites.


Preventing mosquito bites is the best way to protect yourself from EEEV and WNV.


We recommend:

  • 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

  • Removing, or emptying at least 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


Eastern equine encephalitis virus (EEEV) is normally transmitted between wild birds and mosquitoes but can occasionally infect horses and, rarely, humans through infected mosquitoes’ bites, similar to the transmission of West Nile virus (WNV). Humans do not get infected from a horse or another human. Whereas mosquitoes that carry WNV are most commonly found around homes in urbanized areas, the mosquitoes that carry EEEV are usually found close to swampy hardwood forests. Horses can be protected by a vaccine against EEEV but there is no vaccine for humans.


Human infections with EEEV have been rare in Ontario; historically there have been three human cases of EEEV in Ontario, the most recent reported in 2022. There have been none in Ottawa to date. Although rare, the disease is of concern because, like WNV, it can cause a serious neurological disease and even death. Anyone who lives, works, or participates in outdoor activities in or around wooded swampy areas where the virus is active can be at risk.


West Nile virus (WNV), another disease carried by mosquitoes, continues to be a risk for residents. Ottawa Public Health’s WNV mosquito trapping and lab testing program has confirmed 14 positive mosquito pools, and 2 human cases of WNV in Ottawa have been reported to OPH as of August 19, 2024. This is a notable increase over recent years. For additional information on WNV, please visit OttawaPublicHealth.ca/WestNileVirus or see the recent media release from July 19, 2024.


For more information about mosquito-borne viruses in Ottawa, visit Ottawa Public Health, call 613-580-6744 to speak to a public health inspector or call 3-1-1. You can also follow OPH on social media for important updates.




For media inquiries, contact: Media Requests - Ottawa Public Health


For more information on City programs and services, visit ottawa.ca, call 3-1-1 (TTY: 613-580-2401) or 613-580-2400 to contact the City using Canada Video Relay Service. You can also connect with us through Facebook, X (Twitter) and Instagram. 

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