US screwworm patient recovered, Maryland says, as ranchers criticise secrecy
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Screwworms are parasitic flies whose females lay eggs in wounds on any warm-blooded animal.
PHOTO: REUTERS
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CHICAGO/WASHINGTON – The patient with the first human infestation of travel-associated New World screwworm in the United States has recovered from the flesh-eating parasite, and there was no sign of transmission to other people or animals, the Maryland Department of Health said on Aug 25.
US cattle futures tumbled on concerns the pest will also strike livestock as ranchers criticised a lack of transparency about the case, following exclusive reporting by Reuters.
Screwworms are parasitic flies whose females lay eggs in wounds on any warm-blooded animal.
An outbreak could cost the economy in Texas, the biggest US cattle-producing state, about US$1.8 billion (S$2.3 billion), according to US estimates.
The Centres for Disease Control and Prevention (CDC) confirmed the human case as screwworm on Aug 4 in a person who returned from travel to El Salvador, according to the US Department of Health and Human Services.
The agency announced the case on Aug 24 after Reuters reported earlier in the day on e-mails from beef industry officials on a CDC-confirmed case in a person in Maryland
The nearly three-week delay between the confirmation of the case on Aug 4 and the US government's disclosure erodes trust that public agencies need to identify and fight potential screwworm outbreaks, said Mr Neal Wilkins, chief executive of conservation and cattle group East Foundation.
“It will cause many producers and landowners, wildlife managers, to simply begin to believe that they’re not being fed the whole story,” he said. “It’s irresponsible and tone-deaf for them to have done this.”
Maryland’s health department said the patient was a resident of the state but did not respond to questions about the country to which the person travelled or the timing of the case.
A spokesperson for the Department of Health and Human Services did not address the discrepancy on the source of the human case on Aug 24.
Feeder cattle futures fell at the Chicago Mercantile Exchange after cattle and beef prices set records in 2025 because the nation’s herd shrank to its smallest size in 70 years.
Screwworm has spread north in Mexico from Central America, prompting the US Department of Agriculture to halt imports of Mexican cattle in July.
US Department of Agriculture (USDA) Secretary Brooke Rollins did not mention the human case when she travelled to Texas on Aug 15 to announce that the agency would spend up to US$750 million to build a Texas facility to produce sterile flies to combat screwworm.
The agency has not confirmed cases in animals in 2025.
The USDA has not responded to questions about the human case and what communications the agency had with the CDC.
Last week, an executive of industry group Beef Alliance sent e-mails to about two dozen people, informing them the CDC had confirmed a case in Maryland in a person who had travelled to the US from Guatemala, according to a source.
Beef Alliance has not responded to requests for comment.
US cattle producers’ association R-Calf USA said on Aug 25 there should be an investigation if government officials shared information about the case with select industry members.
“Without transparency and symmetrical information dissemination to all industry participants there can be no trust between industry participants and the government,” the association’s CEO, Mr Bill Bullard, said. REUTERS
