Mosquitoes, once a nuisance, are now a threat.” The virus, which is contracted through the bite of an infected mosquito, has been on the rise across the Northeast, prompting Massachusetts coastal towns to shut down parks and playgrounds to better protect residents amid concerns about the deadliness of the disease.

A New York resident contracted the first confirmed human case of Eastern equine encephalitis in the state in nearly a decade and has died, the governor’s office announced this week. So what exactly is the mosquito-borne disease EEE or Triple E?

“While we normally see these mosquitoes in two to three counties each year, this year they have been in 15 counties so far, and scattered all over New York State. This life-threatening mosquito-borne disease has no commercially available human vaccine and must be taken seriously.