As of Aug. 29, West Nile virus had been detected in mosquitoes in 23 Connecticut towns, according to the state Mosquito Trapping and Testing Program. No human cases have been reported yet.

The Department of Public Health (DPH) says West Nile virus is the most common mosquito-borne disease in the United States and reemerges every year in Connecticut, typically in late summer. West Nile was first identified in the United States in 1999 in Queens, N.Y.

Towns with West Nile Virus activity are:

  • Branford
  • Bridgeport
  • Cornwall
  • Darien
  • Fairfield
  • Greenwich
  • Hartford
  • Ledyard
  • Meriden
  • Milford
  • New Canaan
  • New Haven
  • Newington
  • Norwalk
  • Stamford
  • Stratford
  • Wallingford
  • Waterbury
  • Waterford
  • West Haven
  • Westport
  • Wilton
  • Woodstock.

> Want more health news? Text StartHere to 85209 to sign up for text alerts

“We are seeing a sharp rise in the numbers of mosquitoes carrying West Nile virus, especially in coastal Fairfield and New Haven counties and in the metropolitan Hartford area,” said Dr. Philip Armstrong, medical entomologist at the CAES. “We anticipate further geographic spread and build-up of West Nile virus in mosquitoes, with increased risk of human infection, from now through September.”

“The recent heat waves and high humidity have provided favorable conditions for the mosquitoes that transmit West Nile virus,” said Dr. Jason White, director of CAES. “We urge everyone to prevent mosquito bites by using insect repellent and covering bare skin, especially during dusk and dawn when mosquitoes are most active.”

How West Nile virus is spread

Mosquitoes can get the virus after biting an infected bird. In some cases, mosquitoes transmit the virus to horses and other animals, but rarely to humans. West Nile is passed by mosquitoes from bird to bird. Sometimes, a mosquito will infect humans or animals.

What are West Nile virus symptoms?

It starts with headache, fever and body aches, said Neha Alang, MD, an infectious disease specialist based in Norwich. Other symptoms may include:

  • Body aches
  • Headache
  • Rash
  • Diarrhea
  • Vomiting
  • Joint pain

Alang said that usually, mild West Nile illness improves on its own. Typically, people don’t need to seek medical attention, though they may choose to do so. The Centers for Disease Control estimate that 1 in 150 people infected can develop inflammation of the brain (encephalitis) or the lining of the membranes that surround the brain and spinal cord (meningitis).

“If you develop symptoms of severe West Nile illness, such as unusually severe headaches or confusion, seek medical attention immediately,” she said. Such cases usually require hospitalization.

How to protect yourself

To reduce the risk of West Nile Virus and other mosquito-borne diseases, residents should:

  • Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
  • Consider the use of mosquito repellents containing an EPA-registered active ingredient. These include DEET, Picaridin, IR3535, oil of lemon eucalyptus, para-methane-diol (PMD) or 2-undecanone when it is necessary to be outdoors.
  • Wear shoes, socks, long pants and a long-sleeved shirt when outdoors for long periods of time. Choose light-colored and loose-fitting clothen made of tightly woven materials that keep mosquitoes away from the skin.
  • Be sure door and window screens are tight-fitting and in good repair.
  • Use mosquito netting when sleeping outdoors or in an unscreened structure and to protect infants when outdoors.