On July 8, Mexico reported a new case of New World Screwworm in Ixhuatlan de Madero, Veracruz, 370 miles south of the United States-Mexico border, leading to the closure of livestock trade through southern ports of entry into the United States.
This new northward detection comes approximately two months after northern detections were reported in Oaxaca and Veracruz, less than 700 miles away from the U.S. border, which triggered the closure of our ports to Mexican cattle, bison, and horses May 11, 2025. Then, late last month, U.S. officials announced a risk-based, phased port reopening strategy for cattle, bison, and equines from Mexico, beginning as early as July 7—a move now scrapped due to the recent detection. The closure is meant to protect American livestock and the U.S.'s food supply.
According to U.S. officials, this newly reported NWS case raises significant concerns about the previously reported information shared by Mexican officials and severely compromises the outlined port reopening schedule of five ports this summer.
NWS is a pest that causes serious and often deadly damage to livestock, wildlife, pets, and in rare cases, humans. It has been absent from the U.S. for decades.
"The United States has promised to be vigilant—and after detecting this new NWS case, we are pausing the planned port reopenings 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 U.S. Secretary of Agriculture Brooke Rollins. "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."
To ensure the protection of U.S. livestock herds, the United States Department of Agriculture 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.
In June, Secretary Rollins launched a plan to combat NWS with the groundbreaking of a sterile fly dispersal facility in South Texas. This facility will provide a critical contingency capability to disperse sterile flies should a NWS detection be made in the southern United States. Simultaneously, USDA is moving forward with the design process to build a domestic sterile fly production facility to ensure it has the resources to push NWS back to the Darien Gap. USDA is working on these efforts in lockstep with border states—Arizona, New Mexico, and Texas—as it will take a coordinated approach with federal, state, and local partners to keep this pest at bay and out of the U.S.
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.
