Experts Warn Of Deadly Mosquito-Borne Virus That Causes Brain Swelling Found In Florida


The Florida Department of Health in Orange County let residents know that several sentinel chickens in the area tested positive for a mosquito-borne virus called Eastern equine encephalitis (EEE) which has been known to sometimes cause fatal brain infection and swelling.

That means the risk for the virus to spread to people goes up.

Sentinel chickens are used for disease prevention research and are tested regularly for Eastern equine encephalitis and the West Nile virus.

Encephalitis symptoms usually emerge between four and 10 days after the bite, which usually include fever, disorientation and vomiting, according to the Centers for Disease Control and Prevention.

The Centers for Disease Control and Prevention said only about seven cases of EEE get reported in humans in the U.S. every year. But, about 30 percent of the people who do get infected die and many people who survive have neurological problems, according to the CDC.

Symptoms of EEE develop about 4 to 10 days after people are bitten by the mosquito, according to the CDC. Symptoms include headache, high fever, chills and vomiting. More severe symptoms include disorientation, seizures and coma.

People can prevent mosquito bites by using insect repellent and/or wearing long-sleeved shirts and long pants. You should also empty any standing water from around you home to prevent mosquitoes.

About 30 percent of people infected with Eastern equine encephalitis die from the disease.

Barry Alto, an associate professor at the University of Florida Medical Entomological Laboratory in Vero Beach, said the black-tailed mosquito is the primary carrier of encephalitis.

The St. Lucie Mosquito Control District uses chicken flocks as part of an early warning program to detect the presence of St. Louis encephalitis, eastern equine encephalitis and West Nile viruses. Several chickens have recently tested positive for antibodies for West Nile virus in rural areas of St. Lucie County. There are currently no confirmed human cases in the county. (Photo: CONTRIBUTED BY ERICK GILL/ST. LUCIE COUNTY)

This species is most active near swampland during hot, damp summer months and typically bites during the two hours after sunset.

While infections typically rise in the summer, transmission can occur any month of the year, Alto said. Just because the disease was found in Orange County does not mean it is isolated, and it could spread around the state.

The Treasure Coast is no stranger to mosquito-borne illnesses. West Nile virus was found in sentinel chickens in Martin County in 2018. Populations of these chickens are scattered across the state and experts are always monitoring the severity of contamination, Alto said.

“This is a very serious virus,” Alto said. “You do not want to get infected with this.”

Even if the infection is not fatal, encephalitis can have life-long debilitating effects, including mental disorientation and brain damage, Alto said.

Preventing the disease with insecticide has proven difficult, as many mosquito populations are in protected areas that cannot be treated with the repellent.

Health officials said they will continue to monitor the infections and research prevention efforts. Florida Health reminds everyone to take the basic precautions necessary to avoid mosquito bites.

“Floridians should be paying attention to this,” Alto said. “Avoid being bitten by covering up with clothes and repellent.”