On May 11, 2025, USDA Secretary Brooke L. Rollins announced a 15-day suspension of live cattle, horse, and bison imports from Mexico after New World screwworm was detected in Oaxaca and Veracruz. Mexico’s agriculture ministry decries the unilateral move as it weighs joint containment efforts.
On May 11, 2025, U.S. Secretary of Agriculture Brooke L. Rollins ordered an immediate 15-day suspension of all live cattle, horse, and bison imports from Mexico, effective through U.S. ports of entry along the southern border. The decision follows recent detections of the parasitic New World screwworm (NWS) in remote livestock herds as far north as the Mexican states of Oaxaca and Veracruz—roughly 700 miles from the U.S. border. Rollins emphasized that the measure is necessary to protect U.S. animal health and the integrity of the nation’s food supply, describing screwworm as a “national security issue” due to its capacity to cause severe tissue damage and even death in infested animals.
The USDA’s Animal and Plant Health Inspection Service (APHIS), in coordination with U.S. Customs and Border Protection, will review the latest surveillance data in two weeks to determine whether to extend or lift the suspension. APHIS has also committed to continue its sterile insect release program in southern Mexico and Central America—an approach that helped eradicate screwworm from the U.S. in the 1960s—but the recent northward advancement of NWS in Mexican livestock prompted this more restrictive action. Any animals already in holding for U.S. entry will undergo the standard APHIS veterinary inspection and treatment protocols before being admitted.
New World screwworm, a fly whose larvae burrow into the flesh of warm-blooded hosts, was once eradicated from the continental United States through coordinated sterile-insect technique campaigns in the mid-20th century. Originally endemic to South America and the Caribbean, the pest has steadily moved north through Central America over the past two years, with Mexican authorities reporting confirmed outbreaks in Veracruz and Oaxaca in early May 2025. The resurgence poses risks not only to livestock but also to wildlife, companion animals, and even humans—Mexico’s Health Ministry logged the country’s first human case of screwworm myiasis on April 27, involving a 77-year-old woman in Chiapas.
Mexico’s Secretary of Agriculture, Julio Berdegué, criticized the U.S. move as “unilateral” and argued that it undermines ongoing binational efforts to contain the pest. Berdegué noted that Mexican and U.S. agriculture officials met in Washington just days prior to coordinate surveillance and control measures, and he expressed confidence that a mutual resolution could be reached once additional data are reviewed. Nevertheless, the suspension reflects U.S. concerns that the current bi-weekly review cycle and modified inspection protocols have failed to sufficiently halt northward screwworm propagation.
Economic stakes are high on both sides of the border. U.S. cattle producers bear the memory of a past screwworm invasion that took over 30 years to fully eradicate—at a cost of hundreds of millions of dollars in lost productivity and control measures. Meanwhile, Mexico’s livestock export sector, which accounts for trillions of pesos annually, faces disruptions in trade and logistical backlogs at border ports if the suspension is extended. Both governments have repeatedly affirmed their commitment to shared surveillance, field education, and sterile-insect releases as the cornerstone of the eradication strategy.
In addition to live-animal trade curbs, U.S. authorities are intensifying active field surveillance along the border corridor—deploying “Tick Riders” to inspect ranches and wildlife corridors between official ports of entry for potential screwworm infestations. Should any infestations be identified within U.S. territory, APHIS warns that immediate quarantine and treatment protocols would trigger broader movement restrictions, amplifying the stakes for swift containment in Mexico.
Veterinary experts emphasize that successful eradication depends on three core elements: robust active surveillance and rapid response; controlled animal movements to limit pest spread; and sustained sterile-insect release programs to suppress any emergent infestations. While Mexico has ramped up its sterile-insect releases in recent months, U.S. officials maintain that the persistence of NWS outbreaks in regions considered low-risk signaled a need for the import suspension to bolster the joint effort.
As the 15-day review period unfolds, stakeholders on both sides will be watching daily case reports and eradication metrics. A significant window of containment—defined by at least two consecutive weeks without new detections in previously affected regions—could pave the way for the resumption of normal trade flows. Until then, ranchers, exporters, and regulators alike brace for potential cascading effects on prices, logistics, and bilateral agricultural cooperation.
