Birds in five new towns have tested positive for the West Nile virus, the state Department of Public Health said Tuesday.
The birds were found in Brooklyn, East Haven, Newtown, Norwalk and Plainfield.
Infected birds or mosquitoes have been found in 49 Connecticut towns this year.
Mosquitoes can spread the virus to humans, who can then develop potentially deadly encephalitis, or swelling of the brain. Humans cannot pass the virus to one another.
One human case has been reported in Connecticut this year. A man in his 70s from Old Greenwich was diagnosed with West Nile virus last week. He recovering at Stamford Hospital.
Six Connecticut residents tested positive for the virus last year, up from one in 2000. A 90-year-old East Haven woman died in October after showing symptoms the month before.
People should take measures to reduce mosquitoes near their homes and avoid mosquito bites, especially in areas where West Nile has been identified, Public Health Commissioner Joxel Garcia has said.
The department recommends making sure door and window screens are in good condition, minimizing time spent outside at dawn and dusk, wearing tightly woven clothing that covers skin outside and considering using mosquito repellent.