US, Mexico inaugurate sterile fly plant in Chiapas in cross-border screwworm fight

 Mexico and the United States are strengthening bilateral cooperation to contain and eradicate the New World screwworm through a US$51 million sterile fly production facility in Chiapas. The initiative is critical for protecting North America's livestock industry, as the pest has disrupted Mexico's cattle exports, increased sanitary costs and recently reemerged in the United States after more than six decades. The effort directly affects livestock producers, exporters, veterinary services and agricultural authorities, while reinforcing regional biosecurity and agricultural trade stability.

Representatives from Mexico and the United States will meet in Chiapas to inaugurate a sterile fly production facility aimed at combating the New World screwworm. Both countries are intensifying efforts to contain the livestock pest following its recent spread into the United States.

President Claudia Sheinbaum announced that she will travel to Chiapas on Saturday, June 27, alongside Ronald Johnson, US Ambassador to Mexico, and Brooke Rollins, US Minister of Agriculture. The main purpose of the visit is the official inauguration of the sterile fly facility.

Sheinbaum said that the visit reflects the strong relationship and cooperation between both countries. She also emphasized that the project is the result of joint efforts and funding from both governments. "The development of this plant involved resources from Mexico and the United States; and there is ongoing dialogue between our agricultural authorities to address this issue," Sheinbaum said.

The sterile fly production facility, located in Metapa de Domínguez, Chiapas, was refurbished through a binational investment of US$51 million. Mexico contributed US$30 million and the United States provided US$21 million.

The system relies on the mass release of male flies sterilized through radiation, preventing the pest from reproducing and gradually reducing its populations in the field. This internationally validated technique has proven highly effective in eradicating New World screwworm infestations across entire regions, preventing multimillion-dollar losses while reducing the need for chemical insecticides.

The New World screwworm has caused severe economic damage to the livestock sector, affecting cattle, sheep, and other domestic animals. Livestock organizations estimate that, in 2025 alone, losses resulting from the temporary closure of the US border to live cattle imports from Mexico could exceed MX$15 billion (US$800 million), due to declining export sales, increased sanitary costs, and restrictions on animal movement.

In the United States, concerns over the pest's spread led the federal government to allocate US$165 million in emergency funding in 2024 to contain the outbreak and strengthen surveillance and control measures in Mexico and Central America. Historically, the New World screwworm has imposed costs exceeding US$100 million annually on the US livestock industry whenever it has been present.

Concerns intensified after the pest expanded into the United States. On June 3, 2026, the US Department of Agriculture (USDA) confirmed the first case of New World screwworm in the country in more than six decades. Since then, authorities have detected at least 20 cases in Texas and New Mexico, while the USDA has attributed part of the parasite's spread to the irregular movement of cattle across the U.S.-Mexico border.

In 2025, the United States announced a US$750 million investment to build a new sterile fly production facility in Texas. The project remains under development. Construction formally began in April 2026, and the facility is expected to become operational by late 2027. Until then, US authorities will continue relying on sterile insect production from Panama, as well as complementary facilities in Mexico.

In addition, Secretary Rollins' visit will include technical meetings to assess the progress of the plant, evaluate the impact of the initial experimental releases of sterile flies, and update agricultural and veterinary cooperation protocols between the two countries.

President Sheinbaum reiterated the importance of diplomacy in maintaining a positive relationship with the United States despite disagreements on issues such as tariffs and the protection of Mexican nationals in detention centers. "The Mexican government does everything within its power to maintain a good relationship with the United States government, and that relationship must also involve defending our principles. We do not seek conflict with any country in the world, and even less so with our trading partners and neighboring nations," she said.

Mexico Enhances Animal Health Measures 

In line with the Mexican government's efforts to contain and eradicate the New World screwworm, the Ministry of Agriculture and Rural Development (SADER), through the National Service for Agri-Food Health, Safety and Quality (SENASICA), and the International Regional Organization for Plant and Animal Health (OIRSA) are promoting an extensive training program to improve the detection, management, and treatment of suspected cases in Mexico City.

The course, titled Management and Treatment of New World Screwworm in Dogs and Cats, forms part of the broader strategy to control and eradicate the pest. It aims to strengthen the knowledge and technical skills of veterinarians, students, and the general public. More than 1,000 participants have already attended training sessions conducted by SENASICA and OIRSA personnel.

Training courses have so far been held at the Faculty of Veterinary Medicine and Animal Science of the National Autonomous University of Mexico (UNAM), the Federation of Colleges and Associations of Veterinary Zootechnicians of Mexico (FedMVZ), the Natural Resources and Rural Development Commission of the Mexico City government, and at the facilities of the Mexico-United States Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Animal Diseases (CPA), a SENASICAagency located in the Cuajimalpa borough of Mexico City.

To date, SENASICA has inspected more than 5 million head of livestock nationwide and deployed a large network of veterinarians capable of responding within less than 24 hours to reports from producers who detect worms in their animals, providing treatment and collecting samples to confirm or rule out the presence of New World screwworm larvae. In parallel, nearly 7 billion sterile flies have been released in strategic locations, helping reduce wild fly populations and supporting the broader eradication campaign.

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