As summer mosquitoes become active across South Carolina, public health officials are sounding the alarm about a rare but deadly threat. Since May, unusually high mosquito populations have led to a significant increase in Eastern Equine Encephalitis (EEE) virus transmission risk. In late July, the South Carolina Department of Health and Environmental Control confirmed the state's first EEE cases of 2025, including two fatal infections.
What is EEE? Eastern Equine Encephalitis is a mosquito-borne viral disease that causes brain inflammation. While primarily affecting horses and birds, the virus can infect humans through mosquito bites.
Early symptoms of EEE infection include sudden onset of fever, chills, headache, vomiting, and fatigue. In severe cases, which develop in about 20-30% of infections, the disease progresses to neurological symptoms including seizures, paralysis, coma, and permanent brain damage. Approximately one-third of severe cases prove fatal.
Public Health Response
South Carolina health authorities have intensified mosquito surveillance and control measures in affected areas. "We're seeing earlier and more widespread EEE activity than typical for this time of year," said a state epidemiologist. "All residents should take preventive measures seriously."
Recommended precautions include:
- Using EPA-registered insect repellents containing DEET, picaridin, or oil of lemon eucalyptus
- Wearing long sleeves and pants during dawn and dusk when mosquitoes are most active
- Installing or repairing window screens
- Eliminating standing water around homes where mosquitoes breed
Treatment Challenges
No specific antiviral treatment exists for EEE. Medical care focuses on supportive therapy to manage symptoms and prevent secondary infections. Hospitalization is typically required for severe cases, often involving intensive respiratory support and seizure management.
"Early recognition and diagnosis significantly improve outcomes," emphasized state health officials. They advise seeking immediate medical attention for anyone experiencing high fever with confusion, severe headache, or neurological symptoms following mosquito exposure.
Public health monitoring continues as mosquito season reaches its peak, with particular concern for rural areas near freshwater swamps where the primary mosquito vectors breed. While human EEE cases remain rare—averaging about 11 cases annually nationwide—the disease's high mortality rate makes prevention critical.