An Old Lyme resident who contracted eastern equine encephalitis earlier this month has died, state officials announced Tuesday at a news conference in Hartford.

The victim, an adult whose name has not been publicly released, is the second Connecticut resident to contract and die of the mosquito-borne disease in the last several weeks. Patricia Shaw, 77, of East Lyme, died of the disease last Thursday at Lawrence + Memorial Hospital, having contracted it in late August.

State officials had announced Friday that an Old Lyme resident had been infected with the EEE virus and was hospitalized. A spokesman for the Department of Public Health said the resident died late last week.

Lt. Gov. Susan Bysiewicz, who led the news conference, said both of the residents who died were “older adults.”

Bysiewicz said this year’s EEE outbreak is an effect of climate change, noting the virus has been found in Massachusetts and Rhode Island, states where people have tested positive for the disease and several have died. Massachusetts reported a third EEE death Tuesday; Rhode Island has reported one.

“The most important thing we want people to know is that they shouldn’t panic,” Bysiewicz said. “Precautions can be taken. ... Steps include using insect repellent, wearing protective clothing, especially at dusk and dawn ... and limiting time spent outside in the early evening.”

DPH also advises against unnecessary trips into mosquito breeding grounds and marshes, as the mosquitoes that transmit the EEE virus are associated with freshwater swamps, according to a release from Gov. Ned Lamont's office Tuesday evening. Overnight camping or other substantial outdoor exposure in or near freshwater swamps should be avoided.

Renée D. Coleman-Mitchell, the DPH commissioner, said she received an email earlier in the day from a family member of the Old Lyme resident who had died. Amid the tragedy, the family member felt compelled to urge that the state share information about EEE and how to protect against it.

“It was very, very sad to read that email ...,” Coleman-Mitchell said.

About a third of those who contract EEE die of the disease. Of those who survive it, about three-quarters experience neurological problems for the rest of their lives. No vaccine exists to protect against it and no antibiotics fight it. Symptoms can include high fever, headaches, nausea and vomiting and can progress to convulsions and coma.

The virus is introduced by infected birds that migrate in the spring from Florida, where the virus circulates year-round. Mosquitoes pick up the virus when they feed on infected birds and can transmit it to horses and humans. It cannot be transmitted from horses to humans or from one human to another.

Before this year, the only human case of EEE in the state occurred in 2013 and claimed the life of a Killingly resident.

“We’ve known about EEE in Connecticut since 1938, but there were no human cases until 2013. Whatever we’re experiencing this year is different,” said Dr. Matthew Carter, a state epidemiologist. “It’s happening not just in New England, but in New Jersey, all along the East Coast. We haven’t seen anything like this since 1996.”

The Connecticut Agricultural Experiment Station, which traps mosquitos at 92 sites in 72 municipalities in the state, reported this week that an infected mosquito was found in South Windsor, a northcentral Connecticut town outside the area where most infected mosquitoes have been detected.

Infected mosquitoes have been trapped in 12 other towns: Chester, Haddam, Hampton, Groton, Killingworth, Ledyard, Madison, North Stonington, Plainfield, Shelton, Stonington and Voluntown.

“Right now, the greatest risk is east of the Connecticut River,” said Theodore Andreadis, who heads CAES’s mosquito-management program. “The very good news is that we’re seeing the number of mosquitoes declining rapidly. The number of infected mosquitoes has declined dramatically since mid- to late August. With that said, we still have mosquitoes out there and some are infected. ... People should still take precautions.”

Mosquitoes continue to be active until the first heavy frost, Coleman-Mitchell said in the release from Lamont's office.

Andreadis said the areas currently of “greatest concern” are “Stonington, North Stonington, Voluntown — the southeastern corner of the state.”

“We get through the next couple of weeks and we’ll be OK,” he said.

On Tuesday night, Old Lyme First Selectwoman Bonnie Reemsnyder announced her town is taking precautions to limit the risk for the disease.

The state Department of Energy and Environmental Protection undertook ground spraying for mosquitoes at Pachaug State Forest in Voluntown on two occasions in August and September but has no plans to do more, either on the ground or by air, Katie Dykes, the department’s commissioner, said.

Shaw, the East Lyme woman who died of EEE, was hospitalized Aug. 30 at L+M Hospital and was subsequently taken by Life Star helicopter to Yale New Haven Hospital, according to her obituary in The Day. She later was transferred back to L+M, where she died.

She was the wife of Dr. Gerald Shaw, a deacon at St. Matthias parish in East Lyme.

b.hallenbeck@theday.com