State officials are urging Maine residents to take precautions after eastern equine encephalitis was identified in a horse in Somerset County, the latest positive test in what has been an active season for mosquito-borne disease.

The infection of the horse was announced Friday by the Maine Center for Disease Control and Prevention and the Maine Department of Agriculture, Conservation and Forestry. It was the third positive test for EEE in Maine this year.

The Maine CDC has already this year reported cases of EEE in two emus and one wild bird — a turkey in the Waldo County town of Burnham.

Additionally, West Nile virus has been identified in 15 wild birds, including crows found in Sidney and Skowhegan. Jamestown Canyon virus has been found in four mosquito pools.

In the case of the horse, the state released solely its county of residence in order to protect the privacy of its owner, a state official said.

At this time, the CDC said, no human cases of EEE have been identified in Maine this year. A Waldo County resident tested positive for West Nile in July, the first such case since 2018, but officials say the resident acquired the virus while traveling out of state.

However, a New Hampshire resident contracted and died from EEE in August, the first such case and fatality in that state in 10 years.

In Massachusetts, several towns have urged people to avoid going out at night this summer because of the danger of contracting EEE.

The viruses spread to humans and animals through infected mosquitoes. They cannot spread from human to human, or from human to animal.

Many people infected by mosquito-borne viruses have no symptoms, the CDC said. However, mosquito-borne illnesses can be serious and sometimes fatal; about 1 in 3 people who get EEE die and most who recover have long-term physical or cognitive health effects.

These illnesses usually start with flu-like symptoms in humans, the CDC said. Severe symptoms can include brain swelling (encephalitis) and spinal cord inflammation (meningitis). If you experience flu-like symptoms, severe headache, behavior changes, or serious drowsiness, officials asked people to call a health care provider, especially if a COVID-19 test is negative.

People in Maine should take precautions to lower the risk of being infected, the CDC said.

“These positive cases of EEE and West Nile virus should prompt Maine people and visitors to take action to protect themselves whenever they go outside,” said Maine CDC Director Dr. Puthiery Va. “The best way to keep yourself, your loved ones, and domestic animals safe from these serious viruses is to avoid mosquito bites as much as possible.”

The CDC suggests that people wear long sleeves and pants and use adequate repellent on skin and clothes. People should take extra precautions at dusk and dawn, when mosquitoes are most active, and drain artificial sources of standing water around the home to prevent mosquitoes from laying eggs.

State officials also urged horse owners to vaccinate their animals against EEE.

“This confirmation serves as a reminder of the importance of vaccinating horses against this deadly virus,” said Dr. Stefanie Bolas, the state veterinarian. “While horses cannot transmit EEE to humans or other animals, the high mortality rate makes prevention critical. We urge horse owners to take immediate precautions, including ensuring that their horses are up to date on vaccines, using approved insect repellents, and minimizing exposure during peak mosquito activity hours, from dusk to dawn.”