GRAND RAPIDS, Mich. (WOOD) — A horse in Mecosta County has contracted Eastern Equine Encephalitis, a mosquito-borne virus that can be fatal to horses and people, the state says.

The infection of a 7-year-old Standardbred gelding is the first EEE case in a domestic animal so far this year, the Michigan Department of Agriculture and Rural Development said in a Monday release.

EEE is nearly always deadly for horses, but they can be vaccinated against it. The horse in Mecosta County was not vaccinated, MDARD said.

While only a small percentage of people who are infected with EEE will develop serious symptoms, those serious symptoms often prove fatal. Symptoms include fever, chills and body aches. Severe cases can cause headaches, disorientation, tremors, seizures, paralysis, brain damage, coma and death. There is no vaccine for humans.

MDARD also said a horse in Calhoun County, an unvaccinated 4-month-old Belgian colt, has contracted West Nile virus.

“While these are the first confirmed cases of EEE and WNV in domestic animals for 2023, these viruses were already found in mosquito pools and wild birds throughout 14 Michigan counties this season,” State Veterinarian Dr. Nora Wineland said in a statement. “These detections indicate these diseases are present and circulating within the state’s mosquito population, so protecting animals from being exposed to these insects is crucial. Preventing mosquito bites will prevent mosquito-borne diseases.”

In humans, West Nile virus symptoms include headaches, body aches, joint pain and fatigue. About 1 in 150 people infected can develop a serious case, including encephalitis or meningitis. Though it’s rare, West Nile virus can be fatal.

The state says that as of Sept. 8, four people in Michigan, including two in Ottawa County, have contracted West Nile this year. Two other people contracted mosquito-borne Jamestown Canyon virus. No people have been infected with EEE.

EEE and West Nile virus cases usually emerge in late summer and early fall. MDARD reminded people that the threat of mosquito-borne illnesses will continue until the first hard freeze of the season. Storm Team 8 says that usually happens around the first week of October.

You can protect yourself by avoiding mosquito bites:

MDARD advised horse owners to vaccinate the animals against EEE and West Nile, as well as other mosquito-borne illnesses, keep them indoors when mosquito activity is at its peak and use approved insect repellents on them. Call your vet if your animals seem to be sick and report cases of EEE or other mosquito-borne illnesses to MDARD. You can find the reporting form online and email it to