Michigan animal health officials have announced the first case of Eastern equine encephalitis (EEE) in a 3-year-old horse just across the Michigan-Indiana border. While Indiana did not have any reported cases of EEE last year, veterinarians with the Indiana State Board of Animal Health point to the Michigan case as a good reminder to horse owners that the disease can crop up at anytime, anywhere.

Now is the time to take steps to reduce risk, prevent infection and seek help if clinical signs are noticed.

Preventing EEE infection in horses and other equine is best done as a two-pronged approach:

• Vaccinate; and

• Minimize exposure to mosquitoes.

Horse owners should work with their veterinarian to determine a regimen that includes selecting the best vaccine product given in a timely way. Vaccinations are generally administered in the spring for season-long protection. Combination products will prevent several mosquito-borne viruses in a single dose.

Prevention is also accomplished by reducing exposure to mosquito bites:

• Eliminate sources of standing water where the pests breed. Even small amounts of water in old tires, clogged gutters, puddles, or stagnant water troughs can harbor insects.

• Keep livestock confined indoors with good ventilation during peak flight hours, from dusk to dawn.

• If using an insect repellent, select a product labeled for use on that species.

EEE is often called “sleeping sickness” because it causes infected animals to enter a coma. Other clinical signs may include listlessness, high fever, head pressing and seizures. Horses that develop it rarely survive. The EEE virus is maintained in the bird population and is transmitted by mosquitoes that breed in freshwater wetlands. The virus does not spread from horse to horse. Contact a veterinarian if any of these signs are noticed. Testing is available for EEE.

While no equine cases were reported in 2021, parts of northern Indiana will see cases of EEE in some years. In 2020, EEE infections were detected in four horses in LaGrange, Kosciusko and LaPorte counties. One human case of EEE occurred in a LaPorte County resident in 2020. In 2019, EEE infection was detected in 14 horses in Elkhart and LaGrange counties. The infected horses were either not vaccinated or overdue on vaccination. One fatal human case of EEE occurred in Elkhart County in 2019, and 10 human cases occurred in southern Michigan, six of which were fatal.