The Michigan Department of Agriculture and Rural Development (MDARD) has confirmed the first case of West Nile virus (WNV) in a domestic animal this year. A two-year-old horse in Missaukee County tested positive after developing severe neurological symptoms on August 20. The horse, which had not been vaccinated, was humanely euthanized.
State Veterinarian Nora Wineland, DVM, urged animal owners to remain vigilant. “Despite the cooler nightly temperatures, the mosquitoes that carry WNV and other diseases remain active until the first hard freeze,” Wineland said. “It is important to continue taking precautions to keep mosquitoes away from animals.”
WNV is transmitted through the bite of infected mosquitoes and is most often seen in late summer and early fall. The disease primarily affects horses, humans, and birds, though other animals can also become ill. It is not spread directly between horses or from horses to people.
Animal owners can help reduce risk by housing livestock indoors during peak mosquito hours (dusk to dawn), eliminating standing water, using approved insect repellents, and vaccinating horses. Symptoms of WNV in horses may include mild fever and stumbling, which can progress to difficulty standing.
Testing costs for suspected animal cases may be covered through MDARD’s arbovirus grant program. More information is available by calling 800-292-3939.
As of September 5, WNV has also been detected in 27 wild birds, 154 mosquito pools, and 13 human cases across Michigan.
