HARTFORD, Connecticut (WABC) -- A person in Connecticut has died after testing positive for Eastern Equine Encephalitis, and the state has confirmed a fourth case of the rare mosquito-borne disease, state officials said.
The state's department of health announced that an East Haddam resident was confirmed to have Eastern Equine Encephalitis, known as EEE, during the third week of September. The person who is between 60 and 69 years of age, became ill during the second week of September
Health officials also confirmed that another state resident was hospitalized from EEE. The person, a resident of Colchester who is 40 to 49 years old, became ill during the third week of August.
Two other Connecticut resident, one from East Lyme and one from Old Lyme, had died from the disease in September.
RELATED: What is Eastern Equine Encephalitis (EEE)?
The rare virus can cause inflammation in the brain and is potentially deadly. About one-third of patients who develop it die, and many who survive end up having mild to severe brain damage, according to the Centers for Disease Control and Prevention.
It is transmitted through the bite of a mosquito.
There have been seven recorded cases of EEE in Massachusetts and three in Michigan, including one patient who died, according to health officials. Usually, about five to 10 cases are reported annually. At least three New Jersey residents have been sickened.
In July, health officials in Orange County, Florida, announced an uptick in the virus among sentinel chickens, which show the presence of viruses such as EEE and West Nile but don't develop the symptoms associated with them.
Officials say the outbreak is likely the result of mosquitos feeding on infected birds that have migrated north.
Unlike West Nile virus, which can spread in urban and rural areas, the mosquitos that transmit EEE are usually limited to swampy areas. The only defense is to avoid being bitten, which is why residents are being reminded to take precautions.
"Using repellant, covering bare skin, and to be decreasing the amount of time that we are outside, starting from an hour before dusk, and between dusk and dawn," said Renee Coleman-Mitchell of the Connecticut Department of Public Health.
Theodore Andreadis, director of the Connecticut Agricultural Experiment Station, says Connecticut has "never seen this much activity" regarding mosquitoes carrying the virus. The last time there was a death in Connecticut from the virus was 2013.
He says the good news is the mosquito population is dropping as colder weather nears.
ABC News and the Associated Press contributed to this story.
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3rd person diagnosed with EEE in Connecticut has died, officials say