How Worried Should You Be About Getting EEE from Mosquitoes?

Fact checked by Nick BlackmerFact checked by Nick Blackmer

Key Takeaways

• Eastern equine encephalitis (EEE) is a rare but deadly mosquito-borne virus that can leave people extremely ill.

• What makes EEE so deadly is that the virus invades the brain and spinal cord, causing inflammation and swelling.

• Many people who contract EEE die from the illness, and those who survive are often permanently disabled.

Mosquito bites may seem like a harmless summer annoyance, but the rising cases of Eastern equine encephalitis (EEE) in Massachusetts are sparking serious concerns among public health officials.

On July 3rd, the Massachusetts Department of Public Health (MDPH) reported the state’s first case of EEE of the season, with a second confirmed case on August 29. The virus, which is now spreading to humans and horses in other states like New York and Texas, has everyone on high alert.

The latest cases aren’t the first time that Massachusetts has dealt with EEE. According to the state government, EEE outbreaks usually occur every 10–20 years. Between 2019 and 2020, there were 17 human cases and seven deaths.

“Over the years, climate change has attributed to us finding EEE in other areas of the state,” a Massachusetts Department of Agricultural Responses (MDAR) spokesperson told Verywell.

Transmitted by infected mosquitoes, the EEE virus can have severe, if not life-threatening, health consequences. Here’s what you need to know about EEE, along with expert tips on how to protect yourself from the virus.

Related: Eastern Equine Encephalitis: Warning Signs and Recovery

What Is EEE?

“EEE is a rare but serious mosquito-borne disease that occurs in states along the East Coast, the Gulf Coast, and parts of the Upper Midwest,” Catherine M. Brown, DVM, MSc, MPH, an epidemiologist and public health veterinarian for the MDPH, told Verywell. The illness is characterized by a fever between 103 and 106 degrees Fahrenheit, a stiff neck, headache, and lack of energy.

EEE is so dangerous because the virus gets into the brain and spinal cord, causing inflammation and swelling, according to Brown. The disease progressively gets worse, and there is no treatment.

In the state of Massachusetts, about half of the people who have contracted EEE died. According to the Centers for Disease Control and Prevention, about a third of people who get severe illness from EEE will die, and survivors are often permanently disabled.

Related: 9 Reasons Mosquitoes Bite Some People More Than Others

Where Are EEE Hotspots in the U.S.?

Brown said that EEE is primarily associated with swamp habitats. Massachusetts is a swampy state, making it an EEE hotspot.

“In Massachusetts, the virus is most frequently identified in mosquitoes found in and around freshwater, hardwood swamps,” said an MDAR spokesperson, adding that “two types of mosquitoes that carry EEE: those that bite birds and those that bite mammals.”

The spokesperson clarified that “when the virus is found in mosquitoes that bite mammals, the risk of human disease increases because those mosquitoes are much more likely to bite people.”

Other hotspots for EEE in the United States include parts of Florida, Alabama, New York state, Michigan, and Wisconsin, all of which have habitats that support birds that carry the EEE virus and the mosquitos that spread it.

EEE Death in New Hampshire

In late August 2024, the New Hampshire Department of Health and Human Services reported its first case of EEE in 10 years. The patient was hospitalized with severe illness and ultimately died from the infection.

In a statement, New Hampshire State Epidemiologist Benjamin Chan, MD, MPH, said that experts believe there is a higher risk for EEE infections in New England this year, “given the positive mosquito samples identified” and that the risk “will continue into the fall until there is a hard frost that kills the mosquitos.”

Can EEE Be Treated?

There’s no specific treatment for EEE, so prevention is key. Given the current risk of EEE in the state, MDPH and the Massachusetts Department of Agriculture are encouraging state residents to stay indoors during peak biting times, with local boards of health approving the outdoor curfews, according to the MDAR representative. The state will also conduct aerial spraying for mosquitoes in Plymouth County and truck-mounted spraying in Worchester.

“The pesticide used during aerial applications is called Anvil 10+10, an Environmental Protection Agency (EPA)-registered product, which has been extensively tested and used in both ground-level and aerial spraying in the U.S. to control mosquitoes,” said the MDAR spokesperson. While the state is using all available resources, spraying is considered the last line of defense and is only used when the risk of human disease is high.

Spraying adult-infected mosquitoes is an important part of a layered prevention strategy. “While spraying to kill adult-infected mosquitoes is expected to reduce risk, it will not eliminate it,” said Brown. That’s why people are encouraged to take extra precautions, too.

How to Avoid EEE

The virus that causes EEE is spread through mosquito bites, so the MDPH recommends the following to reduce your risk of getting bitten:

• Avoid outdoor activities between dusk and dawn (the times when mosquitoes are most active)

• Wear long pants, socks, and a long-sleeved shirt when you are outside

• Use DEET-based repellent or lemon eucalyptus essential oil

• Fix any holes in the window and door screens in your home

• Remove areas of standing water in your yard

What This Means For You

Amid rising cases of EEE, a rare but deadly mosquito-borne virus, the state of Massachusetts is encouraging residents to take extra precautions, such as sheltering at home during peak mosquito-biting hours, wearing long clothes when outdoors, and using a DEET-based mosquito repellent.

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Read the original article on Verywell Health.