Press Releases
08/07/2025
State Reports Expansion of West Nile Virus
Positive Mosquitoes Identified in 21 Connecticut Towns
MEDIA CONTACT:
Dr. Philip Armstrong
The Connecticut Agricultural Experiment Station
203-974-8510; Philip.Armstrong@ct.gov
John Shepard
The Connecticut Agricultural Experiment Station
203-974-8517; John.Shepard@ct.gov
New Haven – The State Mosquito Management Program is warning Connecticut residents about the increasing risk of infection by West Nile virus (WNV) this season. So far, the Connecticut Agricultural Experiment Station (CAES) has detected WNV-infected mosquitoes in 21 towns: Bethel, Bridgeport, Cheshire, Danbury, Darien, East Haven, Easton, Fairfield, Glastonbury, Greenwich, Groton, Hamden, Hartford, Hebron, Manchester, New Haven, North Branford, Stamford, Stratford, Wallingford, and Wethersfield. There are no reported human cases of WNV so far this season.
“We are seeing a geographic expansion of West Nile virus activity to new towns in Connecticut,” said John Shepard, Medical Entomologist at CAES. “We anticipate further build-up of West Nile virus in mosquitoes, with increased risk of human infection from now through September.”
“Now is the time to take precautions against mosquito bites,” said Dr. Philip Armstrong, Chief Scientist at CAES. "We encourage everyone to take protective measures, such as using insect repellent and covering bare skin, especially during dusk and dawn when mosquitoes are most active."
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.
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 Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) at the University of Connecticut (UCONN). These agencies are responsible for monitoring mosquito populations and the potential public health threat of mosquito-borne diseases.
The CAES maintains a network of 108 mosquito-trapping stations in 88 municipalities throughout the state. Mosquito traps are set Monday – Thursday nights at each site every 10 days on a rotating basis and then at least once a week after detection of virus. 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.
For information on WNV and EEE, what can be done to prevent getting bitten by mosquitoes, the latest mosquito test results and human infections, visit the Connecticut Mosquito Management Program website.