The Ontario Ministry of Agriculture, Food and Rural Affairs confirmed two cases of EEE from the Regional Municipality of Niagara on September 12th, 2018. Both horses were unvaccinated and had no travel history.


One horse is recovering from depression and ataxia with supportive treatment. The other horse was euthanized following the development of sudden and severe neurological signs. The total number of EEE cases for 2018 is ten.

EEE is a mosquito-transmitted disease that is much more severe than West Nile Virus (WNV).  The mortality rate in horses from WNV is reported at around 30%, while the rate for EEE is almost 90%.  Infected mosquitoes are the primary source for EEE.

The virus causes inflammation or swelling of the brain and spinal cord.  General symptoms include central nervous system signs such as: head pressing, convulsions, lack of response to facial stimulation, fever above 103 degrees, ataxia, paralysis, anorexia, depression and stupor.  Other symptoms may include irregular gait, teeth grinding, in-coordination, circling, and staggering.  All symptoms may not be exhibited by an infected horse.