Enlarge / An entomologist for the Louisville Metro Department of Public Health and Wellness in a swampland area on August 25, 2021, in Louisville, Kentucky, collecting various mosquito species and testing the samples for mosquito-borne diseases, such as EEE. (credit: Getty |)

New York is facing an unusual boom in mosquitoes toting the deadly eastern equine encephalitis (EEE) virus, which has already led to one rare death in the state and a declaration of an "imminent threat" by officials.

While the state's surveillance system typically picks up EEE-positive mosquitoes in two or three counties each year, this year there have been 15 affected counties, which are scattered all across New York, State Health Commissioner James McDonald said this week.

"Eastern equine encephalitis is different this year," McDonald said, noting the deadly nature of the infection, which has a mortality rate of between 30 and 50 percent. "Mosquitoes, once a nuisance, are now a threat," McDonald added. "I urge all New Yorkers to prevent mosquito bites by using insect repellents, wearing long-sleeved clothing, and removing free-standing water near their homes. Fall is officially here, but mosquitoes will be around until we see multiple nights of below-freezing temperatures."

Enlarge / A mosquito collected to test for mosquito-borne diseases. (credit: Getty | Jon Cherry)

A small town in Massachusetts is urging residents to stay indoors in the evenings after the spread of a dangerous mosquito-spread virus reached "critical risk level."

The virus causes Eastern equine encephalitis (EEE), which kills between 30 and 50 percent of people who are stricken—who are often children under the age of 15 and the elderly. Around half who survive are left permanently disabled, and some die within a few years due to complications. There is no treatment for EEE. So far, one person in the town—an elderly resident of Oxford—has already become seriously ill with neuroinvasive EEE.

EEE virus is spread by mosquitoes in certain swampy areas of the country, particularly in Atlantic and Gulf Coast states and the Great Lakes region. Mosquitoes shuttle the virus between wild birds and animals, including horses and humans. In humans, the virus causes very few cases in the US each year—an average of 11, according to the Centers for Disease Control and Prevention. But given the extreme risk of EEE, health officials take any spread seriously.