Mosquitoes Carrying Deadly, Brain-Swelling Virus Detected In Central Florida

Adult female black-tailed mosquito (Culiseta melanura). Credit: C. Roxanne Connelly / University of Florida.

ORLANDO, Florida – Florida Department of Health officials are warning the public that mosquitoes carrying a virus that causes brain-swelling and death in humans were detected in sentinel chickens in Orange County, Florida this week.

According to the Florida Department of Health, approximately 30-45% of people with encephalitis caused by EEEV will die from the disease, making it one of the most serious mosquito-borne diseases in the United States. Of those who recover, many will suffer lasting effects.

There is no known medical treatment or cure for the disease.

“Several sentinel chickens in the same flock have tested positive for Eastern equine encephalitis virus (EEEV) infection,” the Orange County Department of Health stated in an advisory. “The risk of transmission to humans has increased.”

Eastern equine encephalitis virus symptoms

Symptoms develop 3-10 days after the bite of an infected mosquito and begin with a sudden onset of fever, general muscle pains, and a headache of increasing severity.

Symptoms can become more severe over 1-2 weeks and infected individuals will either recover or show onset of encephalitis characterized by seizures, vomiting and focal neurological deficits.

Severe encephalitic cases often suffer from coma or death. People under the age of 15 or over 50 seem to be at greatest risk for severe disease.

EEV is a mosquito-borne alphavirus, first recognized in humans in 1938. It cycles between the black-tailed mosquito (Culiseta melanura) and birds in freshwater swampy areas.