Four towns in Massachusetts have implemented a voluntary evening lockdown to reduce the spread of Eastern equine encephalitis, a potentially deadly mosquito-borne disease.

The Massachusetts Department of Public Health recently confirmed the first human case of EEE since 2020 in Worcester County. Subsequently, the Oxford Board of Health voted to recommend that residents stay indoors after 6:00 p.m., a measure effective through September 30.

Starting October 1, the advisory shifts to suggest remaining indoors after 5 p.m. until the first hard frost. According to the public health advisory, the period from dusk through dawn is considered “peak mosquito hours.” The advisory designates four towns — Douglas, Oxford, Sutton, and Webster — as “critical-risk” areas, Fox News reports.

“It is the Board of Health’s responsibility to protect the public health, and we take EEE very seriously, and we are strongly encouraging residents to follow these recommendations due to the severity of EEE and the fact that it is in our community,” a spokesperson for the town of Oxford said in an email to Fox News Digital.

To date, there has been only one human case of EEE in Massachusetts this year. The infected individual, a resident of Oxford, remains hospitalized and is “courageously battling this virus,” according to a memo from the Oxford town manager provided to Fox News Digital.

The evening lockdowns are advisory and will not be enforced if residents choose not to comply. “We want to educate our residents about EEE and the seriousness of the illness and make them aware of the risk,” the town spokesperson said. “However, if they want to use town fields outside these recommendations, they will have to show proof of insurance and sign an indemnification form.”

Last year, EEE killed three people in the state of Massachusetts.