Another human case of Eastern Equine Encephalitis, or “Triple E,” was reported in Massachusetts. It is the state’s first human case of the mosquito-born illness since 2020.

So far this year, three human cases have been reported. Along with Massachusetts, there have also been cases in New Jersey and Vermont. The CDC said most people infected have no symptoms, but others could develop severe neurological problems.

Ned Walker, a professor at Michigan State University said that the illness spreads through mosquito bites mostly in eastern states.

“Primarily along the East coast, but some parts of up-state New York and the Midwest,” Walker said.

Walker says what makes Triple E different from other mosquito-born illnesses is that the virus is extremely dangerous.

“30 to 50% mortality, and then anybody who survives it has some after effects because the virus effects the nervous system,” Walker said.

Earlier this month, a human case was reported in Massachusetts, a state Walker said experts look at to see where the virus is spreading.

“We kind of look to Massachusetts, as you could say, a ‘canary in the coal mine’ for what’s happening,” said Walker.

To protect residents from the virus, including several towns at high risk, the state is now spraying those areas with mosquito-killing pesticides. Something Dawn Wesson, a professor of tropical medicine at Tulane University said can be an effective tool.

“Doing a proactive spraying of that environment. Say if it’s a ball field or a soccer pitch or whatever that might be,” Wesson said.

But spraying isn’t enough. Wesson recommends that everyone wear insect repellant, especially younger kids and older adults that are most at risk.

“Using some kind of a repellant that stays on reliably is going to be important,” said Wesson.