New Haven, CT – The State of Connecticut Mosquito Management Program (MMP) announced that mosquitoes trapped in Colchester on October 14 tested positive for eastern equine encephalitis (EEE) virus. These results represent the first EEE positive mosquitoes identified in the state by the Connecticut Agricultural Experiment Station (CAES) this year. The mosquitoes were Culex pipiens, a predominantly bird-biting species. Connecticut residents are reminded to protect themselves from mosquito bites and mosquito-borne diseases.
“Although the weather has cooled and mosquito populations are declining to low levels, the late season detection of EEE virus in eastern Connecticut warrants attention,” said Philip Armstrong, ScD, Chief Scientist at CAES. “Residents should continue to take measures to prevent mosquito bites, especially during episodes of unseasonably warm weather.”
“The detection of EEE virus in mosquitoes in Colchester is a reminder that mosquito-borne illness can still occur in Connecticut even late in the season," said Department of Public Health Commissioner Manisha Juthani, M.D. "EEE is rare, but it is a serious illness, and the risk of human infection, while low, is not zero until we have a hard freeze. DPH encourages residents to keep taking simple precautions in the days ahead: use an EPA-registered mosquito repellent, cover bare skin when outdoors at dusk and dawn, and make sure window and door screens are in good repair.”
To reduce the risk of being bitten by mosquitoes, residents should:
- Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
- When it is necessary to be outdoors, use mosquito repellents containing an EPA-registered active ingredient, including DEET, Picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol (PMD), or 2-undecanone. EPA registration of skin-applied repellent products indicates that they have been evaluated and approved for human safety and effectiveness when applied according to instructions on the label.
- 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 loose-fitting and made of tightly woven materials that keep mosquitoes away from the skin.
- Wear clothing and gear treated with permethrin. Permethrin is an insecticide that kills or repels mosquitoes and ticks.
- Be sure door and window screens are tight-fitting and in good repair.
- When sleeping outdoors, use tents or mosquito netting in an unscreened structure. Treat camping gear with permethrin when possible.
- Cover strollers and baby carriers with mosquito nets when outside.
EEE is a rare but serious illness in humans with 4-8 cases reported in a typical year in the U.S. The last major outbreak occurred in 2024, involving 19 human cases nationally with 13 of these cases reported in each of the New England states other than Connecticut, and 2 each in New York and New Jersey. EEE is the most severe mosquito-transmitted disease in the U.S. with approximately 40 percent mortality and significant brain damage in half of survivors.
The CAES maintains a network of 108 mosquito-trapping stations in 88 municipalities throughout the state. CAES begins mosquito trapping and testing in June and continues into October. Positive findings are reported to local health departments and on the CAES website at https://portal.ct.gov/caes/mosquitotesting/ introductory/state-of-connecticut-mosquito-trapping-and-arbovirus-testing-program.
Connecticut Mosquito Management Program
The response to mosquito transmitted diseases in Connecticut is a collaborative inter-agency effort involving the Department of Energy and Environmental Protection (DEEP), The Connecticut Agricultural Experiment Station (CAES), the Department of Public Health (DPH), the Department of Agriculture, and the Department of Pathobiology at the University of Connecticut (UCONN). These agencies are responsible for monitoring mosquito populations and the potential public health threat of mosquito-borne diseases.
For information on EEE, WNV and other mosquito-borne diseases, what can be done to prevent getting bitten by mosquitoes, the latest mosquito test results, and human infections, visit the Connecticut Mosquito Management Program web site at https://portal.ct.gov/mosquito.
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