WASHINGTON (BN24) — The United States has again closed its southern border to imports of live livestock, citing the advance of a flesh-eating parasite further north in Mexico than previously reported, American officials said Thursday.
The U.S. Department of Agriculture announced the renewed closure after confirming that the New World screwworm fly, whose larvae feed on the living tissue of warm-blooded animals, had been detected about 185 miles northeast of Mexico City. That location is roughly 160 miles further north than prior infestations and approximately 370 miles from the Texas border.
“Thanks to the aggressive monitoring by USDA staff in the U.S. and in Mexico, we have been able to take quick and decisive action to respond to the spread of this deadly pest,” Agriculture Secretary Brooke Rollins said in a statement Wednesday.
Mexico’s President Claudia Sheinbaum criticized the move, describing it as an overreaction. “From our point of view, they took a totally exaggerated decision to closing the border again,” Sheinbaum said. “Everything that scientifically should be done is being done.”
The New World screwworm fly lays eggs in wounds on livestock and other animals, producing larvae that consume living flesh and bodily fluids—a behavior unusual among fly species. The U.S. had eradicated the parasite domestically in the 1970s by breeding and releasing sterile male flies, and it had been largely confined to Panama until spreading north into southern Mexico late last year.
The U.S. first closed its border in May to imports of live cattle, horses and bison. On June 30, authorities announced that three ports of entry would reopen this month and two more by mid-September. But after the discovery of the new infestation, the USDA ordered the renewed suspension of imports.
Mexico’s agricultural authorities reported that 392 animals were infected nationwide, down nearly 19% since late June.
Three weeks ago, the USDA unveiled a $30 million plan to expand facilities to breed and distribute sterile male flies in hopes of driving down the pest population. Rollins said the U.S. aims to open a new fly-production facility in southern Mexico by July 2026 and is also preparing a Texas site for staging sterile flies imported from Panama in case cross-border releases are needed.
Meanwhile, U.S. Reps. Tony Gonzalez of Texas and Kat McCammack of Florida urged the Trump administration Thursday to fast-track the approval of existing anti-parasite treatments for screwworm infestations in livestock, citing regulatory barriers that limit their use.
Associated Press
