Two local horses test positive for Eastern equine encephalitis

Two horses in Greater Sudbury have tested positive for Eastern equine encephalitis (EEE) virus. These are the first reports of local horses testing positive for the virus.

To date, there have been no reports of human illness caused by EEE virus in the Public Health Sudbury & Districts service area.

While the EEE virus is primarily found in wild birds, the virus can be transmitted to humans and horses by the bite of a mosquito that has fed on the blood of an infected bird. Some people bitten by an infected mosquito will not develop symptoms. Others will experience a sudden onset of headache, high fever, chills, and vomiting. The infection can also be severe and cause the brain tissue to become inflamed (encephalitis) with symptoms including disorientation, seizures, and coma. There is no human vaccine or specific antiviral treatment for EEE virus infections.

While the risk of being infected with Eastern equine encephalitis virus is low, the reports of the infected horses serve as an important reminder to residents to continue to take precautions to avoid illness spread by mosquitoes, as well as other vectors (carriers) such as ticks. Just like with West Nile virus, the best way to protect yourself from EEE is to prevent mosquito bites.

How to avoid being bitten by mosquitoes

  • Use an insect repellent approved by Health Canada and follow the application recommendations on the package.
  • Avoid areas where mosquitoes are known to be present or cover up by wearing light-coloured clothing, long sleeves, and long pants when in mosquito areas such as wooded areas, golf courses, or gardens, especially at dawn and dusk when mosquitoes are most active.
  • Check your window and door screens to ensure that there are no tears or holes for mosquitoes to get through.

Mosquitoes need only a small amount of calm, standing water to lay their eggs and for larvae to hatch. Reduce mosquito breeding areas by changing or removing standing water at least once a week from the following areas:

  • bird baths
  • old tires
  • containers, barrels
  • flower pot saucers
  • swimming pool covers, wading pools
  • clogged gutters and eaves troughs
  • clogged drainage ditches
  • small containers like cans or bottle tops
  • unused children’s toys

Public Health Sudbury & Districts is enhancing its EEE surveillance with mosquito trapping in the area where the positive horses were identified. To date, there have been no positive mosquito pools with EEE found in Public Health Sudbury & Districts’ service area.

For more information and resources about vector-borne diseases, such as EEE and West Nile virus, visit or call 705.522.9200, ext. 464 (toll-free at 1.866.522.9200).

This item was last modified on September 6, 2019