The US Department of Health and Human Services (HHS) on Sunday confirmed the nation’s first human case of travel-associated New World screwworm, a flesh-eating parasite, in a patient who returned from El Salvador.
The case, confirmed by the Centers for Disease Control and Prevention (CDC) on August 4, was investigated alongside the Maryland Department of Health, HHS spokesman Andrew G. Nixon said. He added: “The risk to public health in the United States from this introduction is very low.”
The confirmation comes after the industry sources claimed the CDC had verified a Maryland case linked to travel from Guatemala, highlighting discrepancies over the origin of the infection. Nixon did not address the conflicting accounts.
READ ALSO:Oil Prices Edge Up As Traders Weigh Supply Risks
Screwworms are parasitic flies whose larvae burrow into the flesh of warm-blooded animals. Infestations can be fatal if untreated, though cases in humans are rare.
The case is already rattling cattle ranchers and beef producers, who are on high alert as the parasite spreads northward from Central America and southern Mexico.
The US Department of Agriculture (USDA) estimates a major outbreak could cost Texas — the country’s top cattle-producing state — $1.8 billion in livestock deaths, labour, and medication expenses.
Beth Thompson, South Dakota’s state veterinarian, told Reuters she was notified of the Maryland case last week but criticised the lack of transparency from federal health officials. “We found out via other routes and then had to go to CDC to tell us what was going on,” she said. “They weren’t forthcoming at all.”
Emails seen by Reuters show an executive at the Beef Alliance warning industry members about the human case and stressing that patient privacy laws limited details. The person has reportedly been treated, and prevention measures have been implemented in Maryland.
The outbreak threat has already prompted US Agriculture Secretary Brooke Rollins to announce plans for a sterile fly production facility in Texas, part of efforts to contain the pest. Mexico, where new screwworm cases were detected in July, has begun building its own $51 million facility in the country’s south.
The only operating sterile fly plant is in Panama, with a weekly capacity of 100 million flies — far short of the 500 million the USDA says are needed to drive screwworms back to the Darien Gap between Panama and Colombia.
The parasite was eradicated from the United States in the 1960s using mass releases of sterilised male flies, but its northward spread since 2023 has raised fears of a new outbreak. Mexico recently reported a case just 370 miles south of the US border, triggering the closure of livestock trade through southern ports of entry.
Livestock traders warn that any perception of a US screwworm outbreak could jolt cattle markets already at record highs, with the national herd at its smallest size in seven decades.
