After learning that the East Lyme resident who contracted eastern equine encephalitis died earlier in the week, state Department of Public Health officials announced Friday that an unidentified Old Lyme resident became ill with the mosquito-borne disease last week and remains hospitalized.

Laboratory tests completed Friday at the Centers for Disease Control and Prevention in Fort Collins, Colo., confirmed, in the second case, the presence of the antibodies that fight the EEE virus.

“This afternoon, DPH learned that the first person diagnosed with EEE this year in Connecticut passed away earlier this week,” the department said. “The patient, an adult resident from the Town of East Lyme, was hospitalized with encephalitis in late August.”

The victim, whose name and gender have not been made public, died Thursday at Lawrence + Memorial Hospital, according to sources. A hospital spokesman would not confirm that an EEE patient had been admitted there.

An obituary that will appear in Sunday's edition of The Day identifies the deceased as Patricia Alice “Pat” Shaw, 77, of East Lyme, who it said died at L+M Hospital.

The only previous human case of EEE in Connecticut — also a fatality — occurred in 2013.

“The identification of two Connecticut residents with EEE, one of whom has passed away, emphasizes the seriousness of this infection,” DPH Commissioner Renée Coleman Mitchell said. “Using insect repellent, covering bare skin and avoiding being outdoors from dusk to dawn are effective ways to help keep you from being bitten by mosquitoes. Mosquitoes continue to be active until the first heavy frost.”

The DPH also announced Friday that an adult resident of Danbury has tested positive for West Nile virus, another mosquito-borne infection. It is the first human case of WNV identified in Connecticut this season. The patient became ill with encephalitis during the third week of August and is recovering.

Tests performed at the CDC laboratory confirmed the presence of antibodies to the virus that causes WNV disease.

West Nile virus has been detected in the state every year since 1999. While it has been detected in mosquitoes in the state this season, the numbers of infected mosquitoes identified have been lower than the historical average. The mosquitoes that transmit WNV are most abundant in urban and suburban areas with dense human populations.

Eighty percent of people infected with WNV do not develop symptoms. About 20 percent of those infected develop a fever and other symptoms. About 1 out of 150 infected people develop a serious, sometimes fatal, illness.

In 2018, 23 human cases of WNV virus were identified in Connecticut residents, including one fatality.

States throughout the Northeast are experiencing an usually active season for EEE, the DPH said. The virus, in addition to being found in mosquitoes, has been detected in 10 people in Massachusetts, including two fatalities, and in three people in Rhode Island, including one fatality.

In Connecticut, mosquitoes infected with EEE have been trapped at testing stations in Chester, Haddam, Hampton, Groton, Killingworth, Ledyard, Madison, North Stonington, Plainfield, Shelton, Stonington and Voluntown. Horses have tested positive in Colchester and Columbia.

While the number of mosquitoes is declining, residents of southeastern Connecticut should continue to take precautions. Overnight camping or other substantial outdoor activity should be avoided.

After being bitten by an infected mosquito, it takes 4 to 10 days for a person to develop symptoms of EEE. No vaccine exists to protect against it and there is no specific treatment for it. Symptoms can include high fever, headaches, nausea and vomiting and can progress to convulsions and coma. Severe cases of EEE result in encephalitis, an inflammation of the brain.

About a third of those who develop the disease die. Of those who survive, about three-quarters experience neurological problems for the rest of their lives.

b.hallenbeck@theday.com