Eastern Equine Encephalitis: The Deadly Mosquito-Borne Illness That’s Killed 8

You probably already despise mosquitos — and we’re about to give you a scarier reason than usual to justify that hatred. Eight people have died from a rare virus called Eastern equine encephalitis, which is spread to people by infected mosquitoes. 

Although only about five to 10 human cases are reported each year in the U.S., about 30% of those diagnosed die, and many survivors have ongoing neurological issues, the Centers for Disease Control and Prevention reports. Here’s what to know about this rare but dire infection. 

EEE stems from the mosquito-borne illness referred to as EEEV, which can cause the brain to become inflamed. Again, it’s rare, with only about 4% of human EEEV illnesses turning into full blown EEE, the CDC reports. 

Birds in freshwater hardwood swamps can also be hosts for the disease, but it’s the mosquitoes that spread the disease between the birds and the humans. 

When you first heard about it, you might have questioned what the “equine” part of the name meant. Don’t worry, you won’t get it from your horse. It’s true that horses are susceptible to EEEV, and can die from it. However, it’s not likely your pony would give this disease to you, because the CDC considers them “dead end” hosts, just like humans. 

First: You shouldn’t panic. You’re more likely to get West Nile virus from a mosquito than EEE, Health reports. But it’s still important to be aware of EEE, however infrequent cases are. Health officials are saying this year is set to be the worst year recorded in recent history. There have been over 25 confirmed or suspected cases so far reported across six states, Gizmodo reports. 

Theodore Andreadis, director of The Connecticut Agricultural Experiment Station and head of the Center for Vector Biology & Zoonotic Diseases in Connecticut, told Gizmodo that the concern this year isn’t just about how many people have been diagnosed, but also the fact that it seems to be spreading throughout the eastern U.S. thanks to bugs and birds. “Periodically, you know, you might get an outbreak in Massachusetts, Rhode Island, and not necessarily see it in Connecticut and New Jersey. But this year, it’s really all over the entire region,” Andreadis told Gizmodo.  “And we don’t even know how many other people might have developed mild sickness or been exposed to the virus and not developed any symptoms. So it’s really rather extraordinary this season.”

Massachusetts has seen some real problems this year. Three people there have died, and the state’s Department of Public Health said Monday that there are 10 confirmed cases of the illness that were previously reported. Two people from Connecticut have been diagnosed, and one died. Connecticut’s public health department’s Renée Coleman-Mitchell said in a release: "The identification of two Connecticut residents with EEE, one of whom has passed away, emphasizes the seriousness of this infection.” There was another death earlier this month in Rhode Island, the state’s first human case since 2010, according to a health department news release. 

Meanwhile, three people have died from EEE in Michigan. The CDC has a comprehensive map that shows cases by state from the last few years. Almost all cases from 2009 to 2018 were reported in the eastern U.S., save for one in Montana.  

The CDC notes that EEE can take shape in two different forms: Encephalitic, which causes the swelling in the brain we talked about, and systematic, which sometimes happens before the encephalitic phase.

If you have a systematic infection, you might get chills, fever, or muscle pain. The illness tends to last one to two weeks. Meanwhile, signs and symptoms of encephalitic EEE include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, convulsions, and going into a coma. The two thirds of people who survive this may be left with disabling issues, including intellectual impairment, seizures, and other brain function issues. 

It usually takes people between four and 10 days after being bitten to notice symptoms. 

Doctors don’t have a vaccine for EEEV yet. If they think someone has EEE, there are kinds of supportive treatment they can provide, but there’s not a cure, according to the CDC. That’s the bad news. 

The good news is you can try to prevent getting bitten by mosquitos in general. The best way is to use bug repellent. Specifically look for spray cans and bottles containing the ingredients picaridin, DEET, IR3535 or oil of lemon eucalyptus, the CDC recommends. 

"We continue to emphasize the need for people to protect themselves from mosquito bites," Massachusetts Public Health Commissioner Monica Bharel said last week in a news release. "It is absolutely essential that people take steps to avoid being bitten by a mosquito."

Mosquitos are huge fans of standing water, so it can help to make sure your property is free of it — check buckets, planters, and consider dumping your kid’s pool.