State officials have confirmed the first human case of eastern equine encephalitis (EEE) of the year in an unusually intense summer for mosquito-borne illnesses in Massachusetts.
A MetroWest man in his 60s became ill on July 28 after traveling outside the region and being bitten by a number of mosquitoes, the state Department of Public Health announced in early August. He was hospitalized and released.
While it is unclear where the man contracted EEE, the news came amid other signs the disease is out in force this year.
As of early August, a state lab had found 84 mosquitoes infected with EEE so far this season, officially outnumbering 80 infected insects found all of last year, said state Department of Public Health veterinarian Catherine Brown.
Some of the increase may be a result of increased trapping and testing of mosquitoes in certain high-risk areas. But with a month or two to go in the typical mosquito season, public health officials are wary.
“I would say that EEE activity this year has been particularly intense,” Brown said.
In response to heavy EEE activity in the region, the state in early August raised the risk level from high to critical in West Bridgewater, Easton, Raynham and Taunton, and from moderate to high in Norton and Bridgewater.
Public health officials also plan additional aerial spraying for mosquitoes in these towns. The state also carried out aerial spraying in 21 southeastern Massachusetts towns earlier in the summer.
EEE showed up earlier than usual this season, including in a breed of mosquitoes that bite mammals, as opposed to birds. The disease also has cropped up in scattered areas beyond the usual hotspots, and more towns than usual are considered at risk for EEE, Brown said.
“The fact that we saw it in mammal biters at the same time as we were first identifying it, that was a big concern for us,” Brown said recently.
West Nile Virus, another mosquito-borne disease, has cropped up in some areas, but overall seems intense this season, according to Brown.
There were 13 human cases of EEE from 2004 to 2006 in Massachusetts, and six people died, she said.
The disease tends to drop off after an outbreak like that, but samples of infected mosquitoes have remained relatively high in the past few years. A Raynham resident, Martin Newfield, died of EEE last year.
Regional mosquito control projects have continued work spraying on the ground and dropping larvicide in catch basins and other areas of standing water to kill the bugs before they hatch.