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Texas confirms its first 2 cases of deadly mosquito-borne illness now seen in multiple states

Eastern equine encephalitis has now been confirmed in horses or humans in Texas, Massachusetts and New York.
A mosquito rests on a human's arm.
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The deadly mosquito-borne illness eastern equine encephalitis has been confirmed in two Texas horses, marking the first reported cases of the disease in the state.

The Texas Animal Health Commission said Monday it found the virus in two Houston County horses, about 110 miles north of the city of Houston.

Health officials there urged veterinarians and equine owners to consider vaccinating their horses against EEE as well as western equine encephalitis, Venezuelan equine encephalitis and West Nile virus to reduce the risk of further spread.

What is EEE?

EEE — along with the other mosquito-borne diseases above — is typically spread to animals and humans through the bite of an infected mosquito, which acquires the virus from biting an infected bird or rodent. Once an animal or human is bitten by the infected mosquito, they won't spread the disease, the CDC says.

But despite being a dead-end host, animals and humans that contract the rare virus can still see a serious, potentially even fatal, illness.

In horses, EEE can cause severe brain inflammation, behavior changes, twitching, paralysis and convulsions. Most of those infected with the virus will not survive and often die within two to three days from symptom onset, and those that do survive may have permanent neurological symptoms.

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In humans, an infected mosquito bite will likely cause symptoms within five to 10 days, which can include high fevers, headache, stiff neck, vomiting, seizures, behavioral changes and fatigue, according to Massachusetts health authorities.

Though there are only a few human cases of EEE in the U.S. each year, with most in eastern or Gulf Coast states, the CDC says around 30% of people who are infected die, and many survivors have ongoing neurological problems.

Recent increase in EEE, West Nile cases

Last week, the Massachusetts Department of Public Health said a man in his 80s had been exposed to EEE in Worcester County, marking the first human infection in the state in four years. The discovery raised risk levels in certain towns to critical, while others rose to high or moderate risk.

EEE was first detected in Massachusetts in 1938 and has created outbreaks lasting two to three years every 10 to 20 years since, the state says. With over 115 cases since its onset, Massachusetts says about half have died, and few have recovered completely without disability.

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Also last week, the New York State Department of Health advised residents to avoid mosquito bites after finding EEE in horses in eight of its counties.

The rise of EEE is also coupled with an increase in West Nile cases, which can also affect the nervous system — including the brain — in humans. The illness just sent Dr. Anthony Fauci to the hospital with symptoms like fever, chills and fatigue, but he's expected to make a full recovery.

How to protect yourself against the mosquito-borne diseases

As there are no vaccines to prevent or medicines to treat EEE or West Nile, the CDC says protecting against mosquito bites is the best way to reduce the risk of infection.

Prevention efforts should include:

  • Use an insect repellent with an EPA-registered ingredient like DEET when going outside
  • Avoid peak mosquito hours, from dusk to dawn
  • Wear loose-fitted long-sleeved shirts and pants
  • Mosquito-proof your home by repairing any window screens
  • Drain any standing water where mosquitoes can lay their eggs