IAEA, FAO Launch Nuclear Initiative to Halt Screwworm Spread

The re-emergence of the New World screwworm has triggered a complete United States import ban on live Mexican livestock, disrupting integrated North American agrifood supply chains and threatening significant financial losses for northern Mexico’s ranching corridors. In response, a joint US$1 million IAEA and FAO initiative will deploy nuclear-based sterile insect techniques to suppress the pest population across Central America and Mexico. This biosecurity crisis demands urgent bilateral regulatory enforcement and enhanced cross-border movement controls to combat illegal cattle trafficking and protect the continent's multibillion-dollar cattle industry.

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The International Atomic Energy Agency (IAEA) and the Food and Agriculture Organization (FAO) have initiated a new Coordinated Research Project (CRP) to counter the re-emergence of the New World screwworm (NWS) across Central America, Mexico, and the United States. 

Operating through the Joint FAO/IAEA Center of Nuclear Techniques in Food and Agriculture, the five-year, US$1 million initiative aims to scale up the application of the sterile insect technique (SIT) as regional detections of the livestock pest continue to rise.

The NWS is a parasitic fly that lays eggs in the open wounds of warm-blooded animals. Once hatched, the larvae feed on living tissue, causing infections that can be fatal if left untreated. While a historical 45-year eradication campaign successfully cleared the pest from the United States by 1982 and down through Central America to Panama by 2006, the biological containment barrier in the Darien Gap was breached in 2022.

On June 3, 2026, the United States Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the country's first domestic case in over 40 years, identified in a bovine in Zavala County, Texas, following a continuous northward spread through southern and central Mexican states that triggered a complete United States import ban on live Mexican livestock. 

"Protecting our livestock industry is a national security issue of the utmost importance, and USDA is wasting no time in taking action," said at that time Dudley Hoskins, Undersecretary for Marketing and Regulatory Programs. Hoskins noted that federal models had projected the parasite entering the country in 2025, but coordinated efforts with industry and state partners extended the timeline for domestic preparedness.

The resurgence threatens livestock production, animal welfare, wildlife, and public health. According to IAEA, past eradication efforts provided an estimated US$1.3 billion in annual benefits to livestock producers across the region by preventing animal mortality and maintaining meat and milk production levels. Officials note that containment efforts are driven by changing weather patterns, globalization, and unlawful transboundary animal movements, which have collectively accelerated the parasite's spread. “The return of the New World screwworm is already causing serious damage in the region, threatening animals, livelihoods, and economies,” stressed Rafael Mariano Grossi, Director General, IAEA. 

IAEA’s main containment tool is SIT, a method that uses radiation to sterilize mass-reared male insects. When released into the wild to mate with local populations, they produce no offspring, suppressing the pest population over time. However, emergency response efforts are currently hindered by a severe shortage of sterile flies. The regional demand requires up to 600 million sterile flies per week. The US-Panama Commission (COPEG) facility in Panama is the only operational mass-rearing plant, producing over 100 million flies weekly. Plans to expand production capacity at facilities in Metapa de Dominguez, Mexico, and Mission, Texas, are projected to add up to 400 million flies per week in the coming years.
The newly launched project will assemble experts from more than 20 affected nations, including endemic regions in South America, to optimize the cost-effectiveness of mass-rearing, evaluate strain development, and improve fly release methods. Because current sterile fly production cannot independently halt the infestation, the project will also support member states in implementing complementary suppression measures, including localized insecticide applications, targeted livestock treatments, and enhanced boundary monitoring. “To meet the needs of greater numbers of sterile flies, the project will bring together expertise to improve the cost-effectiveness of mass-rearing, developing and managing screwworm strains, enhancing handling and release methods, and studying mating behaviour and competitiveness,” said Rui Cardoso Pereira, Head of the Insect Pest Control Section, IAEA.

Illegal Cattle Trafficking Behind the Screwworm Spread: USDA 
The cross-border spread of the parasite has been heavily linked to unauthorized livestock movements and illicit supply chains. US Secretary of Agriculture Brooke Rollins stated before the US Senate that illegal cattle trafficking facilitated by Mexican criminal organizations, alongside broader regional migration flows, has undermined established biological containment barriers since the northward advance began moving from Central America through Mexico. “Tens of millions of people moving north toward the United States, bringing their livestock with them, and with the illegal trafficking of cattle by Mexican cartels, we knew this was coming,” Rollins said during the hearing.

While USDA data has confirmed subsequent infestations expanding into three calves and a goat in Texas, as well as a dog in Lea County, New Mexico, federal authorities have not yet released direct forensic evidence linking these specific domestic cases to unauthorized livestock originating from Mexico. 
The intersection of sanitary defense and regional security has forced a renewed focus on strict cross-border animal movement controls. The ongoing threat of broader economic damage to the North American cattle industry has escalated the urgency for high-level bilateral enforcement, requiring enhanced coordination between agricultural inspectors and border security agencies to monitor supply chains.