Michigan confirms first 2026 case of West Nile virus in a domestic animal

The Michigan Department of Agriculture and Rural Development confirmed the state's first detection of West Nile virus in a 3-year-old horse from Missaukee County.

The standardbred-Friesian mare is currently undergoing treatment and is believed to be unvaccinated, according to state officials.

"Despite the recent cooler nightly temperatures being experienced around Michigan, the mosquitoes carrying diseases like WNV, eastern equine encephalitis (EEE) and other mosquito-borne diseases will remain alive and active until there has been at least one hard freeze where the temperatures fall below 28 degrees Fahrenheit," said State Veterinarian Nora Wineland.

Wineland says that Michiganders need to take all possible precautions to keep mosquitoes away from animals, themselves and their families before a hard freeze occurs.

The MDARD says that West Nile virus is transmitted through the bite of an infected mosquito and cannot spread by horse-to-horse or horse-to-human contact. 

The disease typically affects horses, humans and birds and is seen in Michigan from late summer through early fall each year, state officials say.

The MDARD suggests placing livestock in a barn with fans above during peak mosquito activity (from dusk to dawn), eliminating standing water, using an insect repellent approved for the species and contacting a veterinarian to vaccinate horses against mosquito-borne diseases.

Officials also suggest contacting a veterinarian if a horse shows signs of illness, such as mild fever or stumbling.

State officials recommend contacting MDARD at 800-292-3939 for more details on funding to cover testing costs for Michigan animals suspected of having West Nile virus.

What are the symptoms of West Nile virus in humans?

Most people who are infected with West Nile virus do not experience any symptoms or have a mild illness that may include a fever, headache and body aches, according to health officials. However, in some people, West Nile virus can cause serious disease-causing inflammation and swelling of the brain. When an illness is present, it typically begins two to six days after a mosquito bite. 

People over 50 are more likely to develop serious or life-threatening symptoms of West Nile virus. 

How can you protect yourself against mosquito-borne viruses?

Health officials recommend the following tips to protect you and your family from mosquito-borne illnesses like West Nile virus. 

• Limit outdoor activity from dusk to dawn when mosquitoes are most active. Maintain window and door screens to keep mosquitoes out of buildings. 
• Do not prop open doors.
• Treat standing water that cannot be eliminated, such as retention ponds or drainage ditches, with a mosquito larvicide. 
• Wear protective clothing such as long-sleeved shirts and pants.

• Turn over any container that can collect water, such as tires, buckets, planters, toys, pools, birdbaths, pet bowls, flowerpots and trash containers. 
• Clean clogged roof gutters, especially if leaves tend to clog the drains.

• Use an Environmental Protection Agency (EPA)-registered insect repellent.