ensions are rising between the United States and Mexico after a case of New World screwworm was detected just 70 miles south of the Texas border in Nuevo León. U.S. Agriculture Secretary Brooke Rollins directly blamed Mexico for not enforcing key protocols to prevent the pest's spread, warning that the failure to act puts billions of dollars in livestock and beef exports at risk.

According to Rollins, Mexico has not adequately restricted cattle movements in infected zones and is failing to inspect fly traps daily as required. "This is unacceptable," she said at the Ag Outlook Forum in Kansas City, emphasizing that the reopening of livestock trade between the two countries depends on full compliance with existing surveillance agreements.

The U.S. border has remained mostly closed to Mexican cattle imports since May, with this latest detection further delaying a possible reopening. While the screwworm has not entered U.S. territory, its proximity has alarmed officials and the livestock sector alike. The parasite, which feeds on the living tissue of animals, can decimate herds if not contained promptly.

Mexico's agricultural health agency, Senasica, responded by defending its protocols, stating that fly traps are checked every three to four days, in line with a bilateral agreement. The agency also said it has implemented double inspections at points of livestock origin.

President Claudia Sheinbaum said Mexico had not received formal notice of any change to the timeline for border reopening, currently expected before November. She acknowledged the difficulty of controlling internal livestock movement, especially in rural regions.

The USDA learned of the Nuevo León case on September 21 and quickly dispatched personnel to assess the site. The agency said its staff observed insufficient monitoring practices, confirming concerns about Mexico's compliance.

The U.S. has invested $21 million in a sterile fly facility in southern Mexico, part of a long-standing biocontrol strategy designed to reduce wild screwworm populations by releasing flies that cannot reproduce. While the initiative remains active, U.S. officials argue it must be matched by strict on-the-ground enforcement in Mexico.

The incident has added strain to U.S.-Mexico agricultural relations just weeks before a scheduled review of the United States-Mexico-Canada Agreement (USMCA). Both livestock producers and trade officials are watching closely, as any cross-border biosecurity lapse could reshape future beef trade and disease prevention policies.