DPH Confirms First Human Eastern Equine Encephalitis Death in South Carolina in More Than 20 Years

FOR IMMEDIATE RELEASE:
Sept. 19, 2025

COLUMBIA, S.C. — The South Carolina Department of Public Health (DPH) announced today that the state has experienced its first confirmed death caused by infection with eastern equine encephalitis (EEE) virus in more than 20 years.  

This is the first human case of EEE virus to be reported in South Carolina since 2020, and the first fatality from the virus in the state since 2003. EEE virus is spread to people by the bite of an infected mosquito and is not transmissible from person to person. Infection by the virus can cause a febrile illness without neurological symptoms or can cause neurological symptoms and disease due to inflammation and damage to the brain (encephalitis) or lining of the brain and spinal cord (meningitis).

"Sadly, a person from Beaufort County has died from an infection of eastern equine encephalitis virus,” said Dr. Edward Simmer, interim DPH director. “While cases of the virus in people are extremely rare, the effects can be very serious to those who are infected. We encourage everyone to take action to reduce the risk of mosquito bites, including eliminating mosquito breeding sites.”

Approximately 30% of people who develop severe eastern equine encephalitis die, and many survivors have ongoing neurologic problems, according to the Centers for Disease Control and Prevention (CDC).

There are no vaccines to prevent or medicines to treat infection in humans.

The best way to reduce your risk of infection with EEE virus is by preventing mosquito bites. The American Mosquito Control Association recommends wearing long sleeves, long pants and light-colored, loose-fitting clothing when outdoors and properly applying an EPA-registered product that contains a repellent such as catnip oil, oil of citronella, DEET, IR 3535, oil of lemon eucalyptus, picaridin, p-menthane-3,8-diol (PMD), 2-undecanone or wear permethrin-treated clothing. With all repellents, be sure to follow product label instructions.

DPH doesn’t perform mosquito control -- the agency’s role is to provide information that helps individuals, communities and local mosquito control programs take actions to reduce mosquito populations to protect people and animals from mosquito-borne diseases. Mosquito control programs are managed locally by city or county governments.  

Beaufort County Mosquito Control performed multiple spraying applications for mosquitoes by truck in the general area of the human case since the reported illness onset date. Additionally, Beaufort County will spray by helicopter to get more effective coverage.

The county will also set mosquito traps in the area for the purpose of EEE virus testing. Beaufort County’s closest routine surveillance trap to the site was approximately 2.5 miles away, but no EEE-virus positive mosquitoes have been detected thus far in 2025. The county will continue to monitor the mosquito population with increased trapping in the area and will conduct more mosquito spray missions based on that surveillance data.

DPH works in partnership with the CDC to monitor mosquitoes for diseases that can be spread to humans. DPH’s mosquito-borne disease surveillance program includes trapping and testing mosquitoes, accepting and testing dead birds from the public, and working with Clemson University Veterinary Diagnostic Center to test veterinary animals, such as horses. Additionally, DPH does surveillance for and responds to cases in humans of these diseases spread by mosquitoes.  

So far in 2025, we have detected 10 EEE-virus positive horses in Aiken County (3), Colleton County (2), Horry County (1), Jasper County (1), Orangeburg County (1), and Sumter County (2) from mid-July through August.

Mosquitoes can develop in water that stands for more than five days. DPH recommends following the “7 Ts” to keep your home and yard mosquito-free:

• TIP over anything that can hold water, such as toys, plant saucers or vases. To disrupt mosquito breeding cycles, change water often, even daily, in items like dog bowls and bird baths.
• TOSS or recycle any unwanted yard items that may collect water, such as old tires, junk, or trash.
• TURN over items that can hold water like children’s pools, wheelbarrows, or buckets.
• TIGHTEN tarps over items like boats, wood piles, grills, and pools.
• TAKE CARE of your property. Clean out debris from ditches, drains, and gutters. Keep grass cut low and trim or remove overgrown plants.
• TREAT items that can’t be drained or emptied with appropriate mosquito control products.
• TEAM UP and talk with neighbors about reducing mosquitoes in and around your home and neighborhood.

DPH offers educational materials and tips for mosquito prevention, bite prevention and more via its website at dph.sc.gov/vbdoutreach.

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