Michigan Horse Succumbs to Mosquito-Borne EEE

In Michigan, an 18-month-old horse in Roscommon County was euthanized on September 8, 2026, after testing positive for eastern equine encephalitis (EEE). This is the third reported case of EEE in the state this fall, highlighting a recurring health concern.

Earlier on August 31, 2026, a one-year-old colt in Clare County also succumbed to EEE. These animal cases underscore the persistent presence of the virus in the state's mosquito population. Michigan State Veterinarian Dr. Nora Wineland stressed that EEE is preventable through timely vaccinations and diligent mosquito control efforts.

Additionally, a Roscommon County resident fell ill with EEE earlier in August, marking the first human case since 2021. To mitigate risks, officials recommend using DEET-containing repellents, wearing protective clothing, vaccinating animals, and eliminating mosquito breeding sites around homes. Common breeding areas include bird baths, clogged gutters, and containers holding standing water.

Beyond EEE, West Nile Virus remains the most common arbovirus in Michigan, with seven residents diagnosed as of September 4, 2026. Other monitored viruses include Jamestown Canyon Virus and LaCrosse Virus. Mosquito populations are expected to decline with colder weather, typically tapering off in October.