Mexico Ramps Up Screwworm Fight Amid US Cattle Ban

Mexico has fully implemented all the measures agreed upon with the US Department of Agriculture (USDA) to combat the outbreak of the New World Screwworm (NWS), says Julio Berdegué, Minister of Agriculture and Rural Development (SADER). Berdegué met US Agriculture Secretary Brooke Rollins and both agreed that the suspension would last 15 days and be subject to review to reopen the border promptly.

“We began aerial dispersal of sterile flies — an effective method to disrupt the pest’s reproductive cycle — in November 2024,” says Berdegué. These flies are supplied by the only production facility in the world, located in the United States, he adds. He also emphasizes that Mexico had already enacted all bilateral measures by the time the US decision was announced. 

In addition to biological control efforts, Mexico has intensified inspections and restrictions on livestock movement, especially in regions identified as high-risk. If a screwworm case is detected, all ranches within a 20km to 40km radius are quarantined and inspected.

Mexico has also requested US technical support to build a sterile fly production plant in Chiapas. While no official response has been received, authorities stress that establishing local capacity is crucial to long-term containment, especially as the outbreak originated in southern Panama in 2023 and is now moving northward.

Massive Operational Response

According to SADER, since June 2024, over MX$167 million (US$9.5 million) have been allocated to combat the pest. From Nov. 30, 2024, over 885 million sterile flies have been released across southern Mexico from packaging centers in Tuxtla Gutierrez and Tapachula, Chiapas. A new facility at Tuxtla’s airport is expected to release up to 120 million sterile flies weekly by November 2025.

Mexico’s National Service for Agri-food Health, Safety, and Quality (SENASICA) has inspected 9,741 cattle shipments — totaling 610,660 animals — to prevent the spread of infestation northward. Two veterinary certification schemes are in operation in Chiapas and Tabasco, and animals are tagged with sanitary IDs upon inspection.

Additionally, SENASICA maintains 10 permanent inspection points in Chiapas, Campeche, Tabasco, and Veracruz. Field teams respond within 24 hours to reported cases, treat wounds, collect samples, and monitor affected animals for 15 days.

Seventeen more inspection sites have been authorized in Veracruz, Tabasco, Chiapas, and Oaxaca, along with mobile inspection routes and checkpoints. Over 120,000 powdered wound treatment kits and 150,000 larval sampling kits have been distributed.

In collaboration with regional unions, livestock associations, and the National Confederation of Livestock Organizations (CNOG), a national outreach campaign is underway. From January, 1,522 informational sessions have been held, reaching over 60,000 people — mainly ranchers and veterinarians.

Educational materials are being distributed in key southern states, and 33,000 points of contact have been established with support from government agencies and livestock unions to raise awareness.

During his recent visit to Washington DC, Berdegué and Rollins agreed to form a binational working group that will meet weekly to oversee and enhance the NWS eradication campaign.

US Maintains Import Ban Over NWS Concerns

Despite Mexico’s actions, the USDA remains firm on its decision to temporarily suspend imports of cattle, horses, and bison through southern border ports. Rollins cited the continued northward spread of NWS, now detected as far as Oaxaca and Veracruz.

The USDA stated the import suspension would be reviewed monthly and lifted only after containment is achieved. In the meantime, any animals held for US entry will be processed under strict veterinary inspection to ensure they are NWS-free.

According to the National Agricultural Council (CNA), this decision significantly affects northern Mexico’s livestock sector, which previously exported over 5,700 cattle daily through Sonora and Chihuahua, representing a daily loss of US$11.4 million in foreign revenue.

While the CNA supports the binational health strategy and acknowledges the Mexican government’s timely response, it considers the blanket suspension unnecessary — especially in regions already compliant with SENASICA and APHIS health protocols. The CNA calls for an increased investment in sterile fly programs, strengthened health surveillance and anti-smuggling measures, and faster approval of certified livestock crossings. The CNA also urges real cooperation with the United States to protect animal health and ensure continued food security for both nations.

Mexican Ranchers Demand Stronger Measures

According to several media outlets, in response to the US suspension, Mexican cattle producers led by Homero García, President, CNOG, met virtually with Minister Berdegué to express their concern. The CNOG proposed eight emergency measures, including sealing the southern border with Guatemala and increasing federal security presence to prevent illegal cattle trafficking.

They also urged for a higher budget to fight the pest, expanded inspections at feedlots, and regional controls on cattle movement to protect export states. Crucially, ranchers asked to be included in the binational task force to contribute their field knowledge and experience.