The USDA has suspended imports of live cattle, horses and bison from Mexico through southern border ports, effective immediately, due to the resurgence of the New World screwworm (NWS). Screwworm is a parasitic fly that poses a significant threat to livestock and wildlife.
Secretary of Agriculture Brooke Rollins announced the suspension on Sunday, citing detections of the screwworm as far north as Oaxaca and Veracruz, Mexico, approximately 700 miles from the U.S. border. The pest, known for causing myiasis by infesting living tissue, was previously eradicated from the U.S. in the 1980s after 30 years and extensive efforts.
“The United States has ordered the suspension of livestock imports through ports of entry along our southern border after the continued spread of the New World screwworm in Mexico,” Rollins said in an USDA press release. “Secretary Berdegué and I have worked closely on the NWS response; however, it is my duty to take all steps within my control to protect the livestock industry in the United States from this devastating pest. The protection of our animals and safety of our nation’s food supply is a national security issue of the utmost importance. Once we see increased surveillance and eradication efforts, and the positive results of those actions, we remain committed to opening the border for livestock trade. This is not about politics or punishment of Mexico, rather it is about food and animal safety.”
The USDA plans to review the suspension monthly, with a two-week data assessment to evaluate current eradication efforts and refine strategies. Measures include enhanced field surveillance, controlled animal movement and the release of sterile flies to curb the pest's reproduction.
Mexico's response to the suspension has been critical. President Claudia Sheinbaum expressed disagreement with the U.S. decision, labeling it as unfair and asserting Mexico's commitment to collaborating in eradicating the pest. Sheinbaum emphasized that decisions should not be made hastily in response to U.S. statements.
The National Cattlemen's Beef Association (NCBA) supports the USDA's decision, highlighting the risk posed by the screwworm to the U.S. livestock industry. NCBA CEO Colin Woodall noted that previous eradication efforts were costly and time-consuming, and emphasized the importance of preventing the pest's reestablishment.
“For months, NCBA and affiliated state cattle industry associations have been working with USDA officials urging their counterparts in Central America to take stronger action to stop the spread of New World screwworm. In the 1960s, America’s cattle and livestock producers spent years and millions of dollars to eradicate New World screwworm from the United States,” said Woodall.
He added, “USDA’s border closure was entirely avoidable. U.S. government officials, NCBA and leaders from affiliated state cattle industry associations have been sounding the alarm for months. Unfortunately, the Mexican government created unnecessary bureaucratic hurdles which rendered prevention efforts ineffective and allowed screwworm cases to spread unchecked beyond control points in southern Mexico. The Mexican government’s failure to knock down senseless obstacles has left America with no alternative but a closure of the U.S. border until the outbreak is verifiably stopped and the flies pushed back south of Panama’s Darien Gap.”
The suspension follows a previous halt in November 2024 after the detection of screwworm in southern Mexico. Imports resumed in February 2025 under stringent safety protocols, but the continued spread has prompted renewed action. As both nations work to contain the outbreak, the USDA said it remains committed to collaborating with Mexican authorities to implement effective eradication strategies and ensure the health and safety of livestock on both sides of the border.
“We are grateful to Secretary Rollins and the USDA for recognizing the urgent threat posed by the New World Screwworm and making the hard decision to halt animal movement across the southern border,” U.S. Cattlemen’s Association President Justin Tupper says, following an in-depth USDA-APHIS stakeholder briefing that included USCA policy staff. “Generations of ranching families remember the devastation the last NWS outbreak caused. Thanks to USDA’s vigilance and strong partnership with Mexico, we have the tools, surveillance and sterile insect technology to respond, but controlling animal movement and closing ports of entry are essential first steps.”
