Mosquitoes Positive For Eastern Equine Encephalitis Virus

The State Mosquito Management Program announced this week that the first mosquitoes testing positive for eastern equine encephalitis virus (EEE) were trapped on August 23 in Ledyard and in Voluntown.

Mosquitoes trapped on August 24 and 25 in New Haven and on August 25 in Stamford tested positive for West Nile virus (WNV). This season, positive mosquitoes or birds have been identified in a total of 11 towns, including Newtown.

 “In Connecticut, the principal mosquito-transmitted diseases of public health importance build up during August and September,” said Connecticut Department of Public Health Commissioner J. Robert Galvin, MD. “We remind state residents to take the measures necessary to avoid mosquito bites. This is especially important in areas where West Nile or eastern equine encephalitis viruses are identified.”

“It is not unexpected to find EEE in southeastern Connecticut since this region has had a history of the virus,” said Theodore Audreadis, PhD, chief medical entomologist for the Connecticut Agricultural Experiment Station. “The confirmation of EEE highlights the advice to take the threat of mosquito-borne diseases seriously at this time of year. Connecticut will continue to trap and test mosquitoes statewide until October.”

Eastern equine encephalitis is a rare, often serious, disease. Symptoms can include high fever, stiff neck, headache, and lack of energy. Encephalitis, or swelling of the brain, is the most serious symptom. Approximately one-third of persons who develop the disease die. Symptoms generally appear from three to ten days after being bitten by an infected mosquito. There is no licensed vaccine for human use. No confirmed human cases have been identified in Connecticut.

During 2003, two horses were diagnosed with EEE. The horses, stabled in Mansfield and Stonington, were first observed with clinical signs on September 26 and October 1, respectively. Positive mosquitoes were trapped in 14 towns including Bethany, Fairfield, Ledyard, Lyme, New Canaan, Newtown, North Stonington, Plainfield, Shelton, Stafford, Stamford, Stonington, Voluntown, and Weston.

The Connecticut Agricultural Experiment Station (CAES) conducts mosquito trapping and testing in cooperation with local health departments at 91 sites throughout the state from June to October. The 22 mosquito isolations of WNV this year, trapped at these sites, were collected in New Haven (14), West Haven (7), and Bridgeport (1). In addition, positive mosquitoes were trapped in Stratford and Stamford where mosquito research is being conducted.

The State of Connecticut Mosquito Management Program is an interagency program consisting of the Department of Environmental Protection, the Connecticut Agricultural Experiment Station, the Department of Public Health, the Department of Agriculture, and the University of Connecticut Department of Pathobiology and Veterinary Science.