West Nile virus more than 10 times higher in South Carolina compared

With little historical data on the prevalence of West Nile virus in South Carolina, members of the Delores Marie Thomas Research Lab have assessed its presence in the Palmetto State. Led by associate professor of epidemiology Melissa Nolan, the team published its findings in the American Journal of Tropical Medicine and Hygiene. West Nile virus more than 10 times higher in South Carolina compared to national average by Erin Bluvas, University of South Carolina edited by Gaby Clark, reviewed by Andrew Zinin Gaby Clark Scientific Editor Meet our editorial team Behind our editorial process Andrew Zinin Chief Editor Meet our editorial team Behind our editorial process Editors' notes This article has been reviewed according to Science X's editorial process and policies.

Editors have highlighted the following attributes while ensuring the content's credibility: fact-checked peer-reviewed publication trusted source proofread The GIST Add as preferred source Led by associate professor of epidemiology Melissa Nolan, the team published its findings in the American Journal of Tropical Medicine and Hygiene. "The West Nile virus has undergone several evolutions since it was first detected in the United States more than 25 years ago," says Nolan, whose research focuses on infectious diseases, particularly understudied vector-borne viruses. "We conducted a vector-human-pathogen study of the virus's current iteration to better understand its habitat and transmission and found that the number of South Carolinians who had been exposed to the virus was much greater than the national average.

We also learned that the mosquitoes that carry the virus were clustered in affluent urban neighborhoods with greater tree canopy cover and abundant bodies of water." First discovered in the West Nile region of Uganda nearly a century ago, West Nile virus does not cause symptoms in the majority (more than 99%) of people. Unfortunately, the remaining small percentage of infected individuals develop a neurological disease characterized by infection and inflammation of the brain as well as paralysis. Those who survive the acute phase of illness are likely to retain permanent disabilities, such as autonomic dysfunction, chronic kidney failure, depression, retinopathy and chronic fatigue syndrome.

The study, which took place during the summer of 2023, marked the sixth research project—clinical, veterinary or epidemiological—to survey the presence of West Nile virus since it was first discovered in South Carolina in 2003. The death of a Richland County resident in 2022 due to the virus prompted USC scientists to lead a comprehensive study in the same county. Incorporating environmental, mosquito and human sampling, the multipronged study focused on neighborhoods in downtown Columbia—per the recommendation of the state public health entomologist based on previously recorded cases of infection.

The research team collected data using a free West Nile virus antibody test, an exposure and health survey, and free mosquito sampling of the property surrounding participants' homes. "With 22% of the sampled residents possessing West Nile virus antibodies—a rate of more than 10 times higher than the national average of 2%—our research unearthed a hotspot for this infectious disease in central South Carolina," says lead author Elba Fridriksson, an Arnold School alumna who is currently a clinical research coordinator at Prisma Health.

"Our analysis also showed that 5% of the participants had antibodies that indicated a recent infection and that 3% of the mosquito pools we tested were positive for West Nile virus." "These findings are concerning not only because they reveal a much higher prevalence of West Nile virus than the national average but also because South Carolina's estimated incidence rate was previously assumed to be less than 1%," Nolan says. "Now that we have a better idea what we're facing, prompt public health interventions, such as more widespread clinical testing and mosquito mitigation efforts, are critically important to protect the health and well-being of South Carolinians.

Additional research is also needed to better understand the roles of microenvironments, climate change and other risk factors that contribute to increased transmission of West Nile virus." Publication details Elba S. Fridriksson et al, Ecologic Factors Contributing to West Nile Virus Hyperendemicity in Central South Carolina: An Integrated Vector–Human–Environmental Study, The American Journal of Tropical Medicine and Hygiene (2026).

DOI: 10.4269/ajtmh.25-0305 Journal information: American Journal of Tropical Medicine and Hygiene Clinical categories Infectious diseases Common illnesses & Prevention Preventive medicine Dedicated to trustworthy science news. Full profile → Andrew Zinin Master's in physics with research experience.

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