New screwworm case detected near U.S. border as outbreak expands in Mexico cattle

A new case of New World screwworm has been detected in cattle in the northern Mexican state of Nuevo León, the closest instance to the U.S. border since the outbreak began last year. The animal, found in the town of Sabinas Hidalgo, originated in Veracruz, according to Mexico’s National Health for Food Safety and Food Quality Service. The development underscores the rapid spread of the parasite through cattle herds across southern regions and raises fresh concerns about cross-border trade and livestock health.

The case prompted renewed cautions along the border and reinforced existing trade restrictions. U.S. authorities have kept live Mexican cattle imports suspended, a measure tied to the screwworm outbreak. The U.S. border remains closed to Mexican cattle imports over screwworm concerns as agencies monitor developments and coordinate with Mexican counterparts on containment and surveillance. The latest detection comes after officials earlier reported a case in Veracruz on July 9, prompting Washington to maintain import bans that affect cattle, bison and horses moving south across the border.

The parasite, the Cochliomyia hominivorax fly, lays larvae that invade living flesh in warm-blooded animals, including humans. Mexico has reported more than 500 active screwworm cases in cattle across southern states as authorities attempt to contain the spread and prevent further relocation of infected animals. The spread has placed a renewed emphasis on veterinary inspection and quarantine measures at ports of entry and in regional markets, complicating an industry already coping with broader market pressures.

Industry and government officials warn that the northern advance of screwworm into border-adjacent states heightens risk for U.S. cattle producers and could affect long-term supply planning. Colin Woodall, chief executive officer of the National Cattlemen’s Beef Association, said the northward movement “is extremely concerning for the American cattle industry” and stressed the urgency of aggressive containment to protect the domestic supply chain. He noted that the pest’s rapid spread through Mexico serves as a stark reminder of the ongoing threat to producers on both sides of the border.

As the outbreak evolves, Mexico’s Agriculture Secretary Julio Berdegué said the isolated Nuevo León case is being controlled under measures agreed with the United States in August. He emphasized that authorities were implementing targeted responses to prevent further spread and to safeguard livestock health while supporting trade relationships.

U.S. Agriculture Secretary Brooke Rollins echoed the commitment to strong safeguards, saying Washington would take “decisive measures to protect our borders, even in the absence of cooperation,” and confirming that imports of Mexican cattle, bison and horses would remain suspended. The comments reflect a persistent stance of vigilance and border protection aimed at averting a broader, cross-border public-health impact.

The debate over screwworm’s reach has taken on economic significance for Mexico’s ranching sector. The country’s ranching federation has warned that if the cattle-import ban remains in place through the year, losses could reach up to $400 million, underscoring the interplay between animal health and fiscal stability in the sector. Analysts say the situation also highlights the need for diversification and resilience within local processing networks to weather potential shocks from trade disruptions.

Experts say the focus now is on rapid surveillance, quarantine, and eradication measures to prevent a wider geographic spread that could threaten the U.S. herd. The outbreak has already triggered heightened inspections, vaccination and treatment campaigns in affected areas, with authorities coordinating across borders to align strategies for monitoring, reporting and response. While vaccination for screwworm is limited, the priority remains preventing the larvae from spreading to new herds and ensuring that infected animals are treated and removed from circulation promptly.

Local ranchers and stakeholders have called for a balance between strict controls and practical steps to sustain production. Mollie Engelhart, a Texas rancher and former vegan restaurateur, told Fox News Digital that the industry must focus on herd growth and diversified processing capabilities to reduce risk and ensure supply stability in the face of regulatory changes. “The most important thing for our cattle industry right now is to bring our herd size up and diversify processing for major packers,” she said, highlighting the need for local options and resilience in the supply chain.

The broader context remains one of cautious vigilance. The screwworm problem has emerged as a transboundary concern, with Mexico reporting hundreds of active cases and U.S. authorities maintaining suspended imports until confidence grows that the pest is contained. Officials emphasized ongoing cooperation and data-sharing to track movements of potentially affected animals and to calibrate responses across states and borders. Agência de proteção animal e saúde pública and other regulatory bodies continue to monitor livestock movements, laboratory findings, and field reports to prevent a recurrence of transport-linked transmission that could threaten cattle health and regional economies.

As authorities work to close gaps in surveillance and control, the industry is weighing longer-term strategies for risk mitigation. Some producers are considering expanding herd size to improve market leverage and resilience, while others are pursuing investment in local processing facilities to reduce dependence on distant markets. The unfolding situation underscores how animal health incidents can quickly ripple through trade, pricing, and livelihoods, prompting policymakers and industry leaders to align on practical, evidence-based approaches that safeguard both animal welfare and economic stability across North America.