HARTFORD, Conn.– The Connecticut Department of Public Health (DPH) today announced the first human case of West Nile Virus (WNV)-associated illness identified in a Connecticut resident this season. During 2024, a total of 12 human WNV infections were reported in the state.
The case is a male resident of Fairfield County and is between 40–49 years of age. He became ill during the third week of August with WNV infection, was hospitalized, and has since recovered. Laboratory tests confirmed the presence of antibodies to WNV.
“As we gather with family, friends, and neighbors outdoors for the remainder of this summer and into the fall, protecting yourself from mosquito bites is an important step in reducing the risk of West Nile virus infection,” said DPH Commissioner Manisha Juthani, MD. “Some precautions—such as using insect repellent, wearing long sleeves and pants, and limiting time outside at dawn and dusk—can make a big difference in reducing mosquito bites.”
"The mosquitoes that carry West Nile virus are most abundant in urban and suburban areas and are most active between dusk and dawn. We anticipate continued risk for human infection until mosquito activity subsides in October,” added Philip Armstrong, ScD, medical entomologist at the Connecticut Agricultural Experiment Station (CAES).
West Nile virus has been detected in Connecticut every year since 1999 and is the most prevalent mosquito-borne disease in the US. The first WNV positive mosquito pool of the season was collected in Bridgeport on June 11, 2025. Most people infected with WNV do not develop symptoms. About 1 in 5 people who are infected develop West Nile fever, an illness which includes a fever and other symptoms such as body aches, joint pain, headache, or a rash. About 1 out of 150 infected people develop a severe illness affecting the central nervous system. About 1 out of 10 cases of severe illness are fatal. People over the age of 60 are at highest risk of serious illness.
To reduce mosquitoes in and around homes, residents should:
- Remove standing water by emptying or changing water in bird baths, pet dishes, pots, used tires, gutters, and other water-holding containers at least once a week to prevent mosquitoes from breeding.
- Install or repair and use window and door screens.
- Cover water storage containers (buckets, cisterns, rain barrels) with tight-fitting lids.
- Clean and chlorinate swimming pools. When pools are not in use, use pool covers and drain when necessary.
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 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 Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) at the University of Connecticut (UCONN). These agencies are responsible for monitoring 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 through Thursday nights at each site every ten 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 at State of Connecticut Mosquito Trapping and Arbovirus Testing Program.
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