On July 8, 2025, Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality reported a new case of New World Screwworm in Ixhuatlan de Madero, Veracruz in Mexico, which is approximately 160 miles northward of the current sterile fly dispersal grid, on the eastern side of the country and 370 miles south of the US/Mexico border. This new northward detection comes approximately two months after northern detections were reported in Oaxaca and Veracruz, less than 700 miles away from the US border, which triggered the closure of US ports to Mexican cattle, bison and horses on May 11, 2025.

While the US Department of Agriculture previously announced a risk-based phased port re-opening strategy for cattle, bison, and equine from Mexico beginning as early as July 7, 2025, this newly reported NWS case compromises the outlined port reopening schedule of five ports from July 7-Sept. 15. Therefore, in order to protect American livestock and the nation’s food supply, Secretary of Agriculture Brooke Rollins has ordered the closure of livestock trade through southern ports of entry effective immediately.

“The United States has promised to be vigilant — and after detecting this new NWS case, we are pausing the planned port reopening’s to further quarantine and target this deadly pest in Mexico. We must see additional progress combatting NWS in Veracruz and other nearby Mexican states in order to reopen livestock ports along the Southern border,” said Rollins. “Thanks to the aggressive monitoring by USDA staff in the US and in Mexico, we have been able to take quick and decisive action to respond to the spread of this deadly pest.”

To ensure the protection of US livestock herds, USDA is holding Mexico accountable by ensuring proactive measures are being taken to maintain a NWS-free barrier. This is maintained with stringent animal movement controls, surveillance, trapping, and following the proven science to push the NWS barrier south in phases as quickly as possible.

USDA will continue to have personnel perform site visits throughout Mexico to ensure the Mexican government has adequate protocols and surveillance in place to combat this pest effectively and efficiently. 

The National Cattlemen’s Beef Association issued a response to the USDA's announcement.

“A key part of USDA’s strategy for protecting American agriculture is continuously monitoring conditions on the ground,” said NCBA CEO Colin Woodall. “Secretary Rollins has been working to balance the economic needs of US cattle producers who rely on imports while at the same time protecting the overall US cattle herd. The New World screwworm’s northward movement jeopardizes the safety of American agriculture, which is why Secretary Rollins paused cattle movement again until we can push the screwworm further from our border.”

“Secretary Rollins has made significant gains holding Mexico accountable for their role in eradicating the New World screwworm. She successfully removed bureaucratic barriers to the screwworm sterile fly flights and increased surveillance in Mexico. Unfortunately, screwworm continues to move north through Mexico and it’s clear that the United States needs a sterile fly facility of our own here at home. We cannot wait any longer and we urge USDA to immediately begin work on a sterile fly facility,” Woodall said.

Earlier in 2025, USDA announced that Moore Air Base would be the site of a new sterile fly dispersal facility in south Texas. NCBA is now urging USDA to expedite the development of a sterile fly production facility as well to ensure that the US can produce enough flies to safeguard the American cattle industry.

NCBA anticipates this situation will continue to evolve, and will monitor conditions, coordinate with stakeholders and work with USDA to protect US cattle farmers and ranchers.