A man in his 60s from southeastern Massachusetts is the fourth Massachusetts resident to be infected with Eastern equine encephalitis and is currently hospitalized.

The case in a Plymouth County resident triggered state public health officials to raise the threat level for the mosquito-borne illness to “high” in the southeastern communities of Duxbury, Marshfield, Norwell, and Plymouth, and they are recommending that outdoor evening events be cancelled until the first hard frost.

Public health officials also raised the threat level for West Nile virus to high in six Western Massachusetts communities after the 14th case of that illness was reported in a man from Hampden County in his 50s who was hospitalized, but then returned home.

Agawam, Easthampton, Hadley, Northampton, Southampton, and Westfield are now at high risk of West Nile virus, but the threat level does not mean outdoor events need to be cancelled. Health officials also raised the threat level to “high” for West Nile in Lowell and Tewksbury after an investigation of a human case that had already been disclosed.

“Today’s announcement is yet another serious reminder that the threat of mosquito-borne illness is still with us, and will remain so until we see the first hard overnight frost,” said state epidemiologist Dr. Al DeMaria in a statement. “People need to continue to use insect repellant, cover up exposed skin, and avoid being outdoors at dusk and after nightfall when mosquitoes are at their most active.”