Health experts have expressed concern about the spread of eastern equine encephalitis (EEE) in the northeastern U.S. The 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. State health officials announced last week a man in his 80s had caught EEE, 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. Speaking to The Associated Press, infectious disease specialist at University of Massachusetts Memorial Medical Center Dr. Richard Ellison said when the virus does cause an infection it can be "very, very severe." "We have no treatment for it, to do this. And if once someone gets it, it's just- all we can do is provide supportive care, and it can kill people," he said. The mosquito that carried the virus has been on the rise, along with cases of EEE, over the last decade. Dr. Catherine Brown, state epidemiologist at Massachusetts Department of Public Health, said she was "concerned" that the spread was being caused by "likely climate change, effects like a warming temperature, changes in migratory bird patterns, and changes in precipitation activity as well." Authorities in Massachusetts are using trucks and planes this week to spray vulnerable areas, and those in some areas of Massachusetts have been warned to stay indoors when mosquitoes are most active. Dr. Anthony Fauci, the former top U.S. infectious disease expert, was recently hospitalized after he came down with West Nile virus. Both are nasty diseases spread by mosquitoes — though thankfully they are relatively rare. The best way to avoid getting sick is of course to avoid getting bitten, which means taking steps like using repellent, wearing clothing with long sleeves and long pants and staying indoors when the mosquitoes are out. Local health departments also work to reduce mosquito numbers, including spraying neighborhoods with insecticide.