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Marion experiences fifth eastern equine encephalitis case; county remains under mosquito-borne illness advisory

By Florida Department of Health in Marion County

May 25, 2018


OCALA, Fla.An additional horse has tested positive for eastern equine encephalitis, or EEE, this month in Marion County. The county has now had five total cases of EEE reported this year; four cases involved horses, and one involved an emu. All animals were unvaccinated for EEE.

Marion County remains under a mosquito-borne illness advisory due to the number of EEE cases identified locally. The risk of disease transmission from mosquitoes to humans through mosquito bites is currently increased.

Eastern equine encephalitis is a mosquito-borne virus first recognized in humans in 1938. It cycles between mosquitoes and birds in freshwater swampy areas and is capable of infecting mammals, birds, amphibians and reptiles. The disease is 80 to 90 percent fatal in horses and emus and 30 to 45 percent fatal in humans. Symptoms develop three to 10 days after the bite of an infected mosquito. The state averages more than 60 reported cases of equine EEE and one to two human cases annually.

“Residents and visitors should take preventative actions to avoid exposure to mosquitoes,” said Florida Department of Health in Marion County Health Officer Mark Lander. “Drain standing water around your home or property, cover your skin with clothing or repellent and work with a veterinarian to have your horses vaccinated for EEE if they are not currently vaccinated. Please consult your veterinarian or the University of Florida College of Large Animal Medicine for information on how to prevent EEE through vaccination in animals such as emus, alpacas and llamas.”

The department recommends draining standing water around homes and properties to stop mosquitoes from multiplying. It only takes a bottle cap full of water standing still for one week to breed mosquitoes, so it’s important to regularly check for and empty anything that could hold water. For example, garbage cans, buckets, pool or boat covers, tarps and flower pots can all hold excess water and should be emptied or cleared off weekly. Items such as old tires or litter should be disposed of so they don’t collect water. Items like bird baths, pet bowls and water troughs should be emptied and scrubbed weekly. Plastic swimming pools should be emptied when not in use.

The department recommends covering skin with clothing or repellent to further prevent mosquitoes from biting. For practical purposes, this means wearing shoes, socks, long sleeves and long, heavier material pants (such as denim (as opposed to spandex or lycra common in leggings)). Residents should also cover doors and windows with screens to keep mosquitoes out of homes and repair any torn screening.

Residents should use repellents that have DEET, picardin, oil of lemon eucalyptus, para-methane-diol or IR3535 and apply the repellent to exposed skin or onto clothing. Some repellents aren’t suitable for children, so check before use and apply per directions. According to the Centers for Disease Control and Prevention, mosquito repellents containing oil of lemon eucalyptus should not be used on children under 3 years old. DEET is not recommended on children younger than 2 months old; use mosquito nettings to protect children younger than 2 months old. For more information on what repellent is right for you, see:

If you own animals such as emus or hunt wildlife, the department recommends taking additional precautions during this time. Emus infected with EEE virus can expose owners and other animals who are in direct contact with their waste, meat, organs, blood and bodily tissues. Please contact your veterinarian or the Florida Department of Health in Marion County for information on how to safely handle potentially infected emus. Some wildlife can also be infected with EEE or other mosquito-borne viruses. Do not harvest wild game that appears sick, wear gloves when dressing or preparing meat from carcasses of healthy appearing game, and cook meat well.

The department continues to conduct statewide surveillance for mosquito-borne illnesses, including West Nile virus, eastern equine encephalitis, St. Louis encephalitis, malaria, chikungunya, and dengue. For more information, visit For more information on eastern equine encephalitis, go to