West Nile Virus Detected in Isabella County Horse

By Andi Anderson

Dr. Nora Wineland, the State Veterinarian of Michigan, has released a statement regarding the detection of West Nile virus (WNV) in a 12-year-old Standardbred mare from Isabella County. This is the third case of WNV reported in a domestic animal in Michigan in 2023.

The mare was found down and unable to rise on September 27, 2023. Subsequent testing revealed that she was positive for WNV. The horse was unvaccinated against WNV and later succumbed to the disease.

Dr. Wineland is reminding livestock owners that WNV remains a threat, even as the weather cools. Mosquitoes that carry WNV and other mosquito-borne diseases can remain active until there has been a hard freeze, where the temperatures fall below 28 degrees Fahrenheit.

To protect livestock from WNV, Dr. Wineland recommends the following measures:

• Place livestock in a barn under fans during peak mosquito activity (from dusk to dawn).
• Eliminate standing water on your property.
• Use an insect repellant on animals that is approved for the species.
• Contact a veterinarian to vaccinate horses against WNV and other mosquito-borne diseases.

If a horse shows signs of illness, such as a mild fever and stumbling, which can progress to being down and struggling to stand, contact a veterinarian immediately. Funding is available to test animals suspected of having a mosquito-borne disease. Please contact the Michigan Department of Agriculture and Rural Development (MDARD) at 800-292-3939 for more details.

WNV is a viral disease transmitted through the bite of an infected mosquito. While the disease typically affects horses, humans, and birds, it can sometimes cause illness in other animals. The disease is not spread by horse-to-horse or horse-to-human contact. Cases of WNV are typically seen in the late summer through early fall each year in Michigan.

As of October 13, 2023, WNV was also detected in 12 wild birds and 124 mosquito pools throughout Michigan. There were 17 cases of the disease reported in humans as well.

Photo Credit: gettyimages-simplycreativephotography