Eastern Equine Encephalitis (EEE) has been confirmed in the City of Hamilton, Ontario. On August 16, 2025, a 20 year old Standardbred gelding was found in lateral recumbency, unresponsive with muscle tremors. The horse was normal the day before. The horse was euthanized. Serum EEE IgM ELISA was positive. The horse was undervaccinated. There were three additional horses who were exposed. This is the fifth confirmed equine EEE case in Ontario this year. To see past and present EEE cases in Ontario go to:
https://www.oahn.ca/resources/ontario-equine-disease-alerts/ and enter the disease surveillance portal