NEW HAVEN, Conn. (WTNH) — West Nile virus has now been detected in mosquitos found in 33 municipalities in Connecticut, continuing the rush of the insects during the season’s unseasonably warm weather, according to an announcement Tuesday from the Connecticut Agricultural Experiment Station.

A map of those municipalities, and how many positive samples have been found in them, is pictured below:

A map of where West Nile virus has been detected in Connecticut, as of Sept. 12, 2023. (Source: Connecticut Agricultural Experiment Station)

In addition, mosquitos positive for eastern equine encephalitis (EEE) have been found in Hampton, Killingly, Thompson, Tolland, Voluntown and Woodstock. The illness causes about four to eight human cases a year.

The last major outbreak was in 2019, where there were 19 in the New England area, out of 38 nationwide. It has a 40% mortality rate and causes neurological impairment in most survivors.

Officials said that warmer-than-average weather is to blame.

“We are seeing a late season rise in the numbers of mosquitoes carrying EEE virus in communities in eastern Connecticut,” Philip Armstrong, medical entomologist at the Connecticut Agricultural Experiment Station, said in a written announcement. “In addition, we are continuing to detect West Nile virus in numerous towns throughout the state. Late summer-early fall is the critical time of the year when virus activity reaches its peak in the mosquito population and the risk is expected to continue until the first hard frost in October.”

Health officials encourage people to apply insect repellent and cover their bare skin when mosquitos are active at dusk and dawn.