(CNN/Gray News) - Eleven people are dead in the worst outbreak of eastern equine encephalitis (EEE) the U.S. has seen in decades.
EEE is a rare brain infection transmitted through a mosquito bite. It is fatal for about 30% of the people who get it and many of the survivors have ongoing neurological problems, according to the Centers for Disease Control and Prevention.
"There are certain conditions like this year where we have to go above and beyond those normal measures because people's health is at risk," said Ken Ayars with the Rhode Island Department of Environmental management.
Now, scientists are working to figure out why the disease is spreading and what we can do about it.
For the first time in nearly 30 years, aerial spraying is happening in Rhode Island in the last defense of the state's fight against EEE.
It’s among six states with reported cases this year including: Massachusetts, Michigan, New Jersey, North Carolina and Tennessee.
Al Gettman, an entomologist for Rhode Island, has studied mosquitoes for more than 27 years. He tracks their habitats and what diseases they could carry, like West Nile and EEE.
He said he's alarmed by the spike in cases of EEE this year.
"This is a very, very unusual year we're having here in southern New England. Nothing quite like this has been observed before where EEE has become so widespread," Gettman said.
He catches mosquitoes to find reasons behind the widespread outbreak. Recently, at the direction of the state, he started laying more traps.
"We all want to know in this very unusual year, how much of EEE is out there. Where is it? What species of mosquito is it in, etc," he said.
He leaves the traps out overnight, and by morning, they're full.
Then, he takes those traps back to the lab where they mosquitoes are frozen and separated by species.
"That's our weekly routine is produce these vials and get them up to our state health department," Gettman said.
It's there that scientists grind up the mosquitoes and test them for the presence of EEE. The results tell state officials about next steps on how to combat the disease.
It's a process repeated every summer.
"We really can't predict it's going to be a bad summer," Ayars said.
While the disease is cyclical and outbreaks happen every few years, officials say determining why it's setting records now will take time.
"There will be more study about that, but I can say that there's an effect of climate change on weather and weather influences mosquito production," Ayars said.
And for people who are really worried about mosquitoes, Gettman said there are precautions to take.
"The threat is out there, that's certain. The obvious message to the public is to remain vigilant and protect yourself and your families from mosquito bites for the rest of the season," Gettman said.
That protection includes using an EPA-registered insect repellent with an active ingredient of the following: DEET, Picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone.
People also can wear long-sleeved shirts and long pants, as well as eliminating mosquito-friendly environments around the home.
The CDC has more tips and guidance for families on its website.
The threat from mosquitoes will not end until the first frost of the season kills them. For most of New England, that probably is still weeks away.