Press Releases


Eastern Equine Encephalitis Virus Activity Declining in State but Continues to be Detected in Mosquitoes

The State Mosquito Management Program is advising Connecticut residents to continue to take precautionary measures against mosquito bites to reduce the risk of infection with eastern equine encephalitis (EEE).  Despite the cooler temperatures, the Connecticut Agricultural Experiment Station (CAES) continues to detect EEE virus in mosquitoes in several areas of the State.  In the latest test results of mosquitoes collected from September 30 to October 10, EEE virus-infected mosquitoes have been found in Bethany, Chester, Darien, East Lyme, Hampton, Madison, and Ledyard.

"Although mosquito numbers are on the wane, we continue to detect EEE virus in mosquitoes, some of which are being found in new communities,” said Dr. Philip Armstrong, Medical Entomologist at the Connecticut Agricultural Experiment Station (CAES). “We will continue to closely monitor the situation by trapping and testing mosquitoes for EEE throughout the State until the first killing frost."

“The lingering detection of low levels of EEE activity in mosquitoes and discovery of virus in new locales is a pattern we have seen in prior years as birds begin their fall migration”, said Dr. Theodore Andreadis, Director of the Center for Vector Biology & Zoonotic Diseases at the CAES.  "We do not anticipate any further build-up of the virus as mosquitoes breeding is over. We do, however, recommend that residents continue take precautionary measures against mosquito bites such as insect repellent and covering bare skin, especially in wooded areas and during dusk when biting mosquitoes are most active.”

Eastern equine encephalitis is a rare but serious mosquito-borne viral disease in people and horses. On average, there are 6 human cases reported each year in the United States. The mortality rate of hospitalized patients is one-third and approximately one-half of survivors suffer from permanent neurological damage. In Connecticut, outbreaks of EEE have occurred sporadically in horses since 1938 and the first locally-acquired human case and fatality occurred in the fall of 2013. 

This year (2019) infected mosquitoes, horse cases, and/or human cases of EEE infection have been reported from 27 towns.  There have been four human cases including three fatalities and six horse cases, all occurring in the southeastern part of Connecticut.

To reduce the risk of being bitten by mosquitoes residents should:

  • Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
  • Be sure door and window screens are tight-fitting and in good repair.
  • Wear shoes, socks, long pants, and a long-sleeved shirt when outdoors for long periods of time, or when mosquitoes are more active.  Clothing should be light colored and made of tightly woven materials that keep mosquitoes away from the skin.
  • Use mosquito netting when sleeping outdoors or in an unscreened structure and to protect small babies when outdoors.
  • Consider the use of mosquito repellent, according to directions, when it is necessary to be outdoors.

The State of Connecticut Mosquito Management Program is a collaborative effort involving the Department of Energy & 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. These agencies are responsible for monitoring the potential public health threat of mosquito-borne diseases.

The CAES maintains a network of 92 mosquito-trapping stations in 72 municipalities throughout the state. Mosquito traps are set Monday – Thursday nights at each site every ten days on a rotating basis. Mosquitoes are grouped (pooled) for testing according to species, collection site, and date.  Positive findings are reported to local health departments and on the CAES website at

For information on West Nile and eastern equine encephalitis viruses and how to prevent mosquito bites, visit the Connecticut Mosquito Management Program Web site at