August 26, 2025
Currently, the risk to public health in the United States from this introduction is very low.
Department of Health and Human Services spokesperson, Andrew Nixon, told NPR when asked about the first human case of New World screwworm in the U.S. New World screwworm is a flesh-eating parasite, usually known to infect livestock.
Why It Matters: Farmers have been on alert for months over concerns about the screwworm making its way to the U.S., especially threatening cattle. Now, the first U.S. human case of the flesh-eating parasite has been confirmed: a Maryland resident who had recently traveled to El Salvador. The patient has recovered, according to NPR. Timing of the case confirmation is unclear.
Screwworm infestations can devastate livestock. A 1970s outbreak in Texas infected more than a million cattle along with sheep and goats. Today, a similar spread could cost the Texas economy nearly $2 billion, according to the USDA.
What is New World Screwworm? The species, primarily found in South America and the Caribbean, is a fly whose larvae feed on the flesh of warm-blooded animals. While not contagious, human infections can become serious if left untreated. “Because once an infestation starts, that often attracts more flies that lay more eggs. Depending where the wound is, the maggots can make their way into vulnerable tissue like the brain, or the wound can get quite big and then you get sepsis,” explained Max Scott, a professor in the Department of Entomology and Plant Pathology at North Carolina State University.
Noteworthy: On August 15, U.S. Department of Agriculture Secretary Brooke Rollins announced plans to build a Texas facility to produce sterile flies to help fight screwworm, as the cattle industry is already facing difficulties. At the time, officials did not mention the first confirmed human case in the U.S.
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by Kelly Dean, Based in Kentucky.
