A fifth human case of the mosquito-borne virus eastern equine encephalitis has been confirmed, state health officials announced Thursday, prompting three more communities to be designated as facing critical risk.
The Department of Public Health said a man in his 70s from southwestern Middlesex County tested positive for EEE, a serious and potentially fatal disease. As a result, DPH raised the risk level in Ashland, Hopedale and Milford to critical and the risk level in Bellingham, Blackstone and Millville to high.
A total of 32 communities are now at the critical tier, including several adjacent towns in southeastern Massachusetts and around eastern Worcester county. Another 39 are at high risk and 121 are at moderate risk.
Five people have tested positive for EEE this year, the first human cases in Massachusetts since 2013. One woman, Fairhaven's Laurie Sylvia, died late last month after contracting the illness.
Eight horses and one goat also had confirmed cases.
Experts say EEE pops up in cycles in Massachusetts. Two separate outbreaks from 2004 to 2006 and from 2010 to 2012 saw 22 confirmed human cases, 14 of which were in Bristol and Plymouth Counties alone.
Communities will continue truck-mounted mosquito spraying, but aerial spraying has ended for the season because evening temperatures are now too low for the process to work effectively. Health officials urged the public to take individual steps to protect themselves, stressing that reducing exposure to mosquitoes by avoiding outdoors after dusk and by using repellent are among the best strategies.
"Even as the weather begins to cool, it remains critically important that people take steps to protect themselves and their families from mosquito bites," Public Health Commissioner Monica Bharel said in a press release.