On Jun. 19, 2026, the International Atomic Energy Agency (IAEA) and Food and Agriculture Organization of the United Nations (FAO), through their Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, are stepping up efforts to tackle the re-emergence of New World screwworm in Central America, Mexico and the United States through the application of a nuclear technique, as detections increase and emergency response efforts seek to contain the livestock pest.

The New World screwworm (NWS) is a parasitic fly whose larvae infest warm-blooded animals. Female flies lay eggs in open wounds or mucous membranes of warm-blooded animals; once hatched, the larvae burrow into living tissue, enlarging wounds and causing infections that can be fatal if untreated. The IAEA Coordinated Research Project (CRP) launched this week will help countries use the sterile insect technique capacity to halt the NWS’s re-invasion.

The sterile insect technique (SIT) uses radiation to sterilize insects, which are then released to mate with wild populations and produce no offspring, helping suppress pest populations over time. The SIT was central to the eradication of NWS from the US, Mexico and Central America, when a 45-year campaign eradicated the pest from the US in 1982 down to Panama in 2006, with a sterile insect barrier remaining in the Darién Gap in Southern Panama. The barrier was effective until 2022 containing the spread of the fly towards the eradicated area.

The parasite’s recent resurgence poses a serious threat to livestock, animal welfare, wildlife and public health, with potentially severe socioeconomic consequences. On 3 June, the US confirmed its first animal case of NWS in more than 40 years, following the pest’s progressive re-emergence in Central America and Mexico after it was first reported in Panama, north of the barrier in 2022.

Infestations can kill animals and reduce milk and meat production. The previous eradication was estimated to have generated annual benefits of US $1.3 billion for livestock producers in the US, Mexico and Central America.