Mosquitoes testing positive for West Nile virus have been trapped in 40 towns around the state including Groton, Old Lyme, Chester and Westbrook, and the first mosquitoes to test positive for eastern equine encephalitis this season have been trapped in Chester, the state Mosquito Management Program announced today.

The West Nile virus-positive mosquitoes were trapped by the Connecticut Agricultural Experiment Station from June 27 to Aug. 8; the EEE positive mosquitoes were trapped Aug. 8.

“While the identification of mosquitoes infected with eastern equine encephalitis virus occurs during most years, the detection of infected mosquitoes this early in the season is of concern,” Theodore Andreadis, chief medical entomologist at the experiment station, said in a news release.

Mary Jane Lis, state veterinarian with the state Department of Agriculture, urged horse owners to keep vaccinations for EEE, West Nile virus and rabies up to date.

“Owners should call their veterinarians for assistance as soon as a horse becomes sick,” she said.

Positive findings from the statewide network of trapping stations are reported to local health departments and at: www.ct.gov/caes. For information on West Nile virus and preventing mosquito bites, visit: www.ct.gov/mosquito.