(CNN) A Connecticut resident infected with Eastern equine encephalitis has died in the state's first fatality from the disease since 2013, health officials said.

Eastern equine encephalitis is a rare but potentially fatal illness caused by mosquito bites. Several states in the northeast have reported cases of the illness in recent weeks, including a second death reported in Massachusetts on Friday.

In Connecticut, in addition to the death of the first person diagnosed this year, health officials announced a second person has tested positive for Eastern equine encephalitis.

They urged residents to protect themselves and their children by avoiding outdoor activity from dusk to dawn, when mosquitoes are most active.

The patient who tested positive is an adult who became ill during the second week of September and remains hospitalized. Laboratory tests by the Centers for Disease Control and Prevention confirmed the presence of antibodies to the virus that causes the disease.

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