BOSTON — On the heels of what the state’s public health veterinarian called the “most significant” year for West Nile virus ever in Massachusetts last year, officials this month have confirmed the first two human cases of eastern equine encephalitis in the state since 2013.
Briefing the state’s Public Health Council Wednesday on mosquito-borne illnesses, Dr. Catherine Brown said there were 49 human cases of West Nile virus last year but that Massachusetts had seen only “very minimal” EEE activity in mosquitoes in the last six years.
Brown said EEE is cyclical in nature and Massachusetts tends to experience two to three years of “intense activity,” including human cases, followed by a slower period. The last outbreak, she said, was from 2010 to 2012, with seven human cases and three deaths in 2012.
The two human cases of EEE diagnosed so far this year were in a man older than 60 from southern Plymouth County and a man between the ages of 19 and 30 in eastern Worcester County. The DPH announced those cases on Aug. 10 and Aug. 16, respectively, and raised the risk level for the virus in nearby communities.
The DPH and the Department of Agricultural Resources have also announced aerial spraying for mosquitoes in parts of southeastern Massachusetts and in parts of Worcester and Middlesex counties to reduce residents’ risk of contracting the serious and potentially fatal illness.
Brown highlighted a map of nationwide EEE exposure from 1964 through 2012, which she said shows “exactly how profoundly Massachusetts is impacted” by the virus. Over that time period, 47 cases were logged in Massachusetts, second only to Florida’s 71.
Georgia was next at 28, followed by New Jersey at 20, North Carolina at 18 and Louisiana at 17.
“To explain why Massachusetts is so disproportionately affected nationally, it’s that we have the exact right type of habitat to support the ecology that EEE occurs in,” Brown said. “So we have these red maple, white cedar swamps in a very high concentration, particularly in Bristol and Plymouth counties. We have some of the largest swamps and largest concentrations of them on the East Coast, which explains the activity that we have.”
To avoid mosquito bites and reduce the risk of contracting EEE, the Department of Public Health is advising that people apply insect repellent when outdoors and wear long sleeves, pants and socks; reschedule outdoor activities that would occur during the “peak biting times” from dawn to dusk; drain standing water around their homes and yards; install or repair screens; and speak to veterinarians about mosquito repellents approved for use on animals.
At the end of Brown’s presentation, Public Health Council member Paul Lanzikos, the executive director North Shore Elder Services, presented her with a gift — a copy of the book, “The Mosquito: A Human History of Our Deadliest Predator.”
As council members laughed, Brown said, “After a hard frost, when the mosquitoes are gone, I will have time to look at this.”