Map of US states where EEE virus is prevalent

Eastern equine encephalitis (also known as EEE or triple E) is a rare mosquito-borne viral disease that has killed at least two people and infected 11 in the United States this year. A deadly virus outbreak in the Northeast has stoked fears of an epidemic and put some areas on high alert.

The EEE virus is transmitted to humans through the bite of an infected mosquito. Centers for Disease Control and PreventionIn humans, the EEE virus attacks the central nervous system, causing swelling and brain damage. About one-third of people with EEE die.

Mosquito season isn't over yet In the United States, activity may continue into November in some states.

“The risk of EEE does not end with Labor Day,” said Dr. Katherine M. Brown, a Massachusetts state epidemiologist. In a statement.

As the Triple E virus continues to spread, here's what you need to know.

EEE Trends 2024

The United States is currently experiencing a triple E virus outbreak in the Northeast. Human cases of eastern equine encephalitis have been confirmed in at least seven states this year. Massachusetts has dominated the U.S. EEE outbreak this summer, but cases have also been reported in New Hampshire, New York, New Jersey, Vermont, Rhode Island, and Wisconsin.

EEE in New York

on monday, Governor Kathy Hockle A New York state resident has died from eastern equine encephalitis. The case, confirmed in Ulster County on Sept. 20, was the first case of EEE in New York state in 10 years, state health officials said. It said in a release.

The news comes less than a month after New Hampshire officials announced Death of a healthy 41-year-old man Cases of the virus have been reported in at least five other states.

The state issued a “Declaration of an Imminent Public Health Threat from EEE” on September 23, freeing up state resources to prevent the spread of EEE, including mosquito control efforts through November. the governor's office said in a press release..

Massachusetts EEE

September 9th, Massachusetts Department of Public Health This marks the fourth confirmed case of EEE in the state this year, with two cases reported in Middlesex County, one in Worcester County and one in Plymouth County.

At least 95 mosquitoes have sampled positive for EEE in Massachusetts so far this year, including two cases in horses. authorities said in a press release.Currently, 14 towns in the state are considered to be at critical or high risk for EEE.

“Massachusetts has not seen an outbreak of EEE in four years,” said Dr. Robbie Goldstein, the state's health commissioner. press release.

As of Sept. 24, 13 towns in Massachusetts are considered high risk, meaning they have a higher chance of leading to cases of EEE. State-by-State DataFour towns in Worcester County are at “significant risk,” meaning there is an extremely high risk from the EEE virus due to positive tests in the area.

What is EEE?

EEE stands for Eastern Equine Encephalitis, a rare but deadly infection caused by the Eastern Equine Encephalitis virus, which can infect mosquitoes, humans and a variety of animals. Centers for Disease Control and PreventionThe virus has been found in North America and the Caribbean.

In humans, the virus affects the central nervous system – the brain and spinal cord – and can cause severe illness or death.

There are only a handful of cases of eastern equine encephalitis each year in the United States, but the number of cases from year to year can vary. According to the CDC:.

“We see a few cases every year, but some years we have an outbreak where mosquitoes, birds, migratory birds, bird immunity all come together and we get dozens of cases,” Dr. Daniel Pastura, chief of neuroinfectious diseases and global neurology at the University of Colorado School of Medicine, told TODAY.com.

There were seven cases in the United States in 2023, one in 2021, and 13 in 2020. There were 38 cases in the United States in 2019, the highest annual number of cases in more than a decade.

Most cases are reported between July and October, Pastura said, with infections peaking in the summer during mosquito season, but cases can continue into the fall in some regions and climates. According to the Cleveland Clinic.

What is the EEE mortality rate?

Eastern equine encephalitis causes inflammation and swelling of the brain, which kills about 30 percent of those who become infected, Pastura said, and survivors often suffer long-term neurological problems, according to the CDC.

How does Eastern Equine Encephalitis spread to humans?

In nature, eastern equine encephalitis virus is maintained through a cycle of transmission between mosquitoes (specifically a species known as the “black-legged mosquito,” Culiseta melanura), freshwater hardwood swamps, and wild birds, which serve as reservoirs for the virus, Pastura noted.

This species of mosquito feeds primarily on birds and is therefore not the primary vector of the virus to humans. According to the CDC:.

Eastern equine encephalitis virus spreads to humans by infecting other mosquito species that feed on humans and birds (such as the Culex mosquito, which also transmits West Nile virus), creating a “bridge” between infected birds and uninfected humans and animals, Pastura said.

Humans are considered the “definitive host”: Eastern equine encephalitis is not transmitted from person to person or from horse to person.

Pastura noted that there have been rare instances of Eastern equine encephalitis being transmitted to humans through organ transplants.

Signs of EEE in humans

Most people infected with eastern equine encephalitis do not develop symptoms.

Symptoms of EEE include:

• heat
• cold
• Muscle pain
• Joint pain

According to the CDC, these symptoms usually last one to two weeks, and most people recover fully if their central nervous system is not affected by the virus.

“About 5 percent of people who become infected can develop a very severe encephalitis,” Pastura said.

Severe infection with eastern equine encephalitis can cause neurological disease and lead to inflammation of the brain (encephalitis) and inflammation of the tissues around the brain and spinal cord (meningitis).

According to the CDC:Symptoms of severe eastern equine encephalitis include:

• High fever
• Behavioral changes
• Seizures
• vomiting
• diarrhea
• Top

These complications can be life-threatening, with approximately one in three people who contract eastern equine encephalitis dying. Many who recover have long-term mental and physical problems, including intellectual disability, seizures and personality disorders. According to the CDC:.

Pastura said the age groups most affected by severe infections are children under 15 and adults over 50.

Incubation period of EEE

If EEE symptoms occur, they usually begin within 4 to 10 days after being bitten by an infected mosquito. According to the CDC:. According to the Massachusetts Department of Health:Symptoms may begin as soon as three days after being bitten.

Where is EEE located in the United States?

In the U.S., cases of eastern equine encephalitis are most prevalent in states along the East Coast, the Gulf Coast and the Great Lakes, Pastura said.

According to the Cleveland Clinic, infections most commonly occur around freshwater bodies and swamps.

Between 2003 and 2023, at least 196 cases of EEE were reported in the United States, primarily in the Atlantic states. Historical CDC data.

EEE virus map for the United States in 2024

According to CDC data: As of September 17, at least 11 human cases of eastern equine encephalitis have been reported in the United States this year, according to data from the New York State Department of Health. All 11 cases have been of the more severe (neuroinvasive) disease. These cases have been reported in seven states.

• Massachusetts
• New Hampshire
• New Jersey
• new york
• Rhode Island
• Vermont
• Wisconsin

So far this year, Massachusetts has reported the most human cases of EEE, with four.

Cases are likely to increase as mosquito season continues and CDC data is updated with reports from state and local health departments.

EEE Virus Treatment

There is no cure or specific treatment for eastern equine encephalitis, and because the infection is caused by a virus, antibiotics are ineffective.

Treatment often focuses on relieving symptoms and includes rest, drinking fluids to prevent dehydration, and over-the-counter pain relievers. According to the Cleveland Clinic.

Severe cases of eastern equine encephalitis will require hospital treatment and additional monitoring and supportive care.

How to prevent Eastern equine encephalitis

There is no vaccine to prevent eastern equine encephalitis, and avoiding mosquito bites is the best way to reduce your risk of eastern equine encephalitis and other mosquito-borne diseases, Pastura said.

To prevent mosquito bites, take the following measures: According to the CDC::

• Apply EPA registered insect repellent
• Please wear long sleeve shirts and long pants when going out
• Limit outdoor activity between dusk and dawn, when mosquitoes are most active.
• Use a screen door to prevent insects from entering
• Throw out or drain standing water around the home where mosquitoes may breed.
• Avoid using Homemade mosquito repellentAccording to experts, these are ineffective.