A rare but deadly disease spread by mosquitoes has one town in Massachusetts closing its parks and fields each evening. Four other towns are urging people to avoid going outdoors at night. They’re concerned about eastern equine encephalitis .

State health officials announced last week a man in his 80s had caught the disease, the first human case found in Massachusetts since 2020. The town of Plymouth, about 40 miles (64 kilometers) southeast of Boston, announced Friday that it’s closing public outdoor recreation facilities from dusk until dawn each day after a horse in the town was infected with the disease. Meanwhile, state health officials warned that a cluster of four towns south of Worcester — Douglas, Oxford, Sutton and Webster — are at “critical risk” after a man from Oxford caught the virus.

State and local health officials urged people in those towns to avoid the peak mosquito biting times by finishing outdoor activities by 6 p.m. until Sept.

30 and then by 5 p.m. after that, until the first hard frost.

They also recommend that people across Massachusetts use mosquito repellents when outdoors and drain any standing water around their homes. Jennifer Callahan, Oxford’s town manager, wrote in a memo that the family of the man who caught the virus in mid August had reached out to her office. “They want people to be aware this is an extremely serious disease with terrible physical and emotional consequences, regardless if the person manages to live,” Cal.