Press Releases
08/27/2025
Continued Risk of West Nile Virus
Positive Mosquitoes Identified in 34 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 risk of infection by West Nile virus (WNV) this season. The Connecticut Agricultural Experiment Station (CAES) has detected WNV-infected mosquitoes in 34 towns this season: Bethel, Bridgeport, Cheshire, Danbury, Darien, East Haven, Easton, Fairfield, Glastonbury, Greenwich, Groton, Guilford, Hamden, Hartford, Hebron, Manchester, Meriden, Milford, New Britain, New Haven, Newington, North Branford, North Stonington, Norwalk, Old Lyme, Southington, Stafford, Stamford, Stratford, Wallingford, West Hartford, West Haven, Westport, and Wethersfield. No human cases of WNV have been reported so far this season but now is often the time of year when the first cases are reported to public health.
“We continue to detect West Nile virus in mosquitoes throughout Connecticut, with the highest levels of activity in Fairfield and New Haven counties and in the metropolitan Hartford area,” said John Shepard, Medical Entomologist at CAES. “This includes infection of mammalian-biting mosquitoes, which increases risk of human infection.”
“West Nile virus transmission is expected to continue until mosquito activity ceases in October," said Dr. Philip Armstrong, Chief Scientist at CAES. "We encourage everyone to take simple measures to prevent mosquito bites. This includes applying insect repellent and covering bare skin, especially in wooded areas and during dusk and dawn when biting 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.
West Nile virus is the most common mosquito-borne viral disease in the United States and occurs every summer in Connecticut. Most people infected with WNV do not experience any symptoms. However, about one in five develop West Nile fever, which includes symptoms such as fever, body aches, joint pain, headache, and rash. In rare cases—approximately one in 150—WNV can cause a severe illness that affects the central nervous system. Of those severe cases, about one in 10 are fatal. Adults over the age of 60 are at the highest risk of serious illness.
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, how to prevent getting bitten by mosquitoes, and the latest mosquito test results, visit the Connecticut Mosquito Management Program website. More information on human infections and prevention is on the CDC website.