What is EEE? The mosquito-borne virus that killed a New York resident, explained.
A New York resident who tested positive for eastern equine encephalitis has died, prompting questions about the rare mosquito-borne disease.
Eastern equine encephalitis, also called EEE, is "exceedingly rare," Dr. Céline Gounder, CBS News medical contributor and editor-at-large for public health at KFF Health News, said on "CBS Mornings."
"I only saw one case, that was about 20 years ago in Massachusetts, and most providers will never see a case of 'Triple E,' as we call it," she said.
Earlier this year, a New Hampshire man also died of EEE. The 41-year-old was hospitalized due to severe central nervous system disease and died within a week. He was healthy and had no underlying conditions.
Another New Hampshire man was fighting for his life after testing positive for three mosquito-borne viruses, including EEE, West Nile virus and St. Louis encephalitis.
The virus typically spreads in certain swamps, including red maple and white cedar swamps in Massachusetts, and experts think horses may be a host animal, hence the word "equine" in the name.
"This is something that we see with many infectious diseases — that the host might be another animal, maybe a bat, which is what we suspect with COVID, for example, or with Ebola," Gounder said. "But in this case, what we think is happening is horses, perhaps other animals are the host. Mosquitoes are biting them and then transmitting that infection to humans."
There have been additional cases of eastern equine encephalitis in the U.S. this year, according to the U.S. Centers for Disease Control and Prevention, including in Rhode Island, New Jersey, Vermont, Wisconsin and Massachusetts.
The New York case, the state's first human case since 2015, prompted health officials to declare an "imminent threat to the public for EEE," Gov. Kathy Hochul announced Monday. The declaration enables the state to assist local governments with EEE prevention and response, such as mosquito spraying efforts.
CDC Director Mandy Cohen previously warned that a warming climate is also affecting these kinds of outbreaks.
"The impact of heat on our health and climate change is not only impacting us as humans, but it's changing where mosquitoes and ticks live, and thus what diseases are moving around in different regions. We're just seeing more bugs, and some of those bugs are becoming resistant to our control methods resistant bugs," Cohen told CBS News.
EEE symptoms
Most people infected with eastern equine encephalitis don't develop symptoms, but some can come down with fever or swelling of the brain.
According to the CDC, symptoms can also include:
- Headache
- Vomiting
- Diarrhea
- Seizures
- Behavioral changes
- Drowsiness
"Approximately 30% of people with eastern equine encephalitis die, and many survivors have ongoing neurologic problems," the CDC notes.
How to protect against EEE
There are no vaccines to prevent eastern equine encephalitis and no medicines to treat it, so the best way to not get sick is avoiding bug bites.
To do this, experts suggest:
- Using insect repellent
- Wearing long-sleeved clothing
- Staying indoors when mosquitoes are out
- Draining standing water
People in some areas of Massachusetts have been warned to stay indoors when mosquitoes are most active, typically at dusk and dawn. Authorities in the state are also using trucks and planes to spray vulnerable areas with insecticide.
Controlling mosquitoes is an important step, Gounder said.
"There are some newer technologies there to control mosquitoes that don't involve pesticides. Some of those are being piloted in place like the Florida Keys, where you have lots of mosquitoes, but we still have a lot to go in terms of developing treatments or vaccines," she said.
Map shows states with EEE cases in 2024
The CDC and state health departments are tracking cases of EEE, as seen in the map below. New cases will appear on the map after being reported to the CDC, but there may be some delays; the CDC says it updates its data every one to two weeks between June and December.
The Associated Press contributed reporting.