Why Is EEE Highest In Southeastern Massachusetts?

BOSTON (CBS) - Eastern Equine Encephalitis is at critical or high risk levels in 37 towns in Massachusetts, many of them in the southeastern part of the state.

So what makes that region so susceptible?

"EEE activity is generated from a specific type of habitat - Red Maple/White Cedar swamps. Southeastern Massachusetts (specifically Bristol and Plymouth Counties) has the highest concentration of these swamps in Massachusetts and in fact, one of the highest concentrations along the entire east coast," a Massachusetts Department of Public Health spokesperson told WBZ-TV.

So far this summer, 311 positive samples of EEE have been found in mosquitoes. Two positive cases have been found in humans, one in southern Plymouth County and one in Grafton. They're first human cases of the disease in Massachusetts since 2013.

Read: EEE Fact Sheet

Gabrielle Sakolsky, an entomologist at the Cape Cod Mosquito Control Project, said she's never seen anything like this summer's levels.

"This is an historic event with high levels of Eastern Equine Encephalitis all over the Commonwealth and this is the most samples we've ever had come back positive," she told WBZ.

Why?

"Last fall we still had water in all of our swamps, The types of mosquitoes that amplify this disease and transmit this disease, they're the type of mosquitoes that spend the winter in their larvae stages and so if it dries out over the winter you start the season with very low populations of these mosquitoes. Unfortunately, that's not what happened last fall."

EEE can be fatal in humans. It's spread through the bite of an infected mosquito.

Read: EEE Survivor Says Don't Ignore Warnings

"It's concerning at this point because we continue to pick up mosquitoes that are testing positive," Sakolsky said. "So people really need to take all of the precautions they can to make sure they're not getting bitten between dusk and dawn."

The risk of EEE will remain until the first killing frost.

For more information on how you can protect yourself, visit the DPH web site.