The Department of Health and Human Services reported on Sunday the nation's first travel-associated human case of New World screwworm, a flesh-eating parasite, linked to an ongoing outbreak in Central America.
First Travel-Linked New World Screwworm Case In America
HHS spokesman Andrew G. Nixon told Reuters on Sunday that the Centers for Disease Control and Prevention confirmed the diagnosis on Aug. 4 in a patient investigated with Maryland health officials who "returned from travel to El Salvador."
"The risk to public health in the United States from this introduction is very low," Nixon said.
Industry sources told Reuters last week the CDC had confirmed a Maryland case linked to travel from Guatemala, a discrepancy Nixon did not address. A Maryland state official also confirmed a case, while the CDC has deferred questions to the state and has not issued a broader public statement.
"We found out via other routes and then had to go to CDC to tell us what was going on," said Beth Thompson, South Dakota's state veterinarian. "They weren't forthcoming at all. They turned it back over to the state to confirm anything that had happened or what had been found in this traveler."
Do Screwworms Infest Humans?
According to the CDC, screwworms are parasitic flies whose larvae burrow into living tissue after eggs are laid in wounds. The eggs typically hatch within about 10–12 hours, and the larvae burrow into living tissue, enlarging and deepening the wound. Odors and fluids from the lesion can attract additional females and escalate the infestation. Though they primarily afflict livestock and wildlife, they can infest people in rare cases.
Untreated infestations can be fatal, but clinicians can usually manage cases by promptly removing larvae and disinfecting or debriding the wound, with additional therapy as needed. The flies thrive in tropical and subtropical regions, which is why U.S. cases are said to be travel-associated.
The United States previously eradicated the New World screwworm using the sterile insect technique and maintains a biocontrol barrier via a joint USDA–Panama program.
Screwworm Impact On Beef And Cattle Demand
Beef and cattle markets, already tight as the U.S. herd sits near a seven-decade low, are watching for any sign of spillover to animals. CME live cattle futures set record highs in late July amid scarce supplies and traders have cited both tightness and screwworm headlines as supportive.
According to a Reuters report from last week, authorities have halted most Mexican cattle imports at times this year and are intensifying control efforts. USDA plans a sterile-fly production facility at Moore Air Base in Edinburg, Texas, part of a long-running eradication strategy also used in Panama and Mexico. The department has warned an outbreak could cost Texas about $1.8 billion.
"This is a pest we don't want back. This is a bad thing," said David Anderson, a Texas A&M University livestock economist. "I can't imagine having to deal with that. It's gross."
Beef prices at U.S. retailers have hovered near records this summer, reflecting historically small cattle supplies. Market watchers say additional screwworm scares could add a risk premium even if public-health risk remains limited.
Photo Courtesy: Gdisalvo on Shutterstock.com
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