The United States is preparing to deploy a novel biological countermeasure against the New World screwworm, a parasitic fly that threatens livestock and wildlife. The strategy involves releasing sterile male flies and specially trained detector dogs to identify infestations. Britain’s Animal and Plant Health Agency is monitoring developments closely, given the potential risk to UK agriculture and the global trade in live animals.
Screwworm infestations occur when female flies lay eggs in open wounds of warm-blooded animals. The larvae feed on living tissue, causing severe injury and often death. The pest has been detected in Mexico and parts of Central America, with outbreaks occasionally reaching the southern United States. The current US plan, coordinated by the Department of Agriculture, aims to establish a sterile insect technique programme combined with canine detection units at key border crossings.
Sterile insect technique involves rearing large numbers of male flies, sterilising them with radiation, and releasing them into infested areas. Mating with wild females produces no offspring, gradually suppressing the population. The method has been used successfully against screwworm since the 1950s, but recent climate shifts and increased movement of animals have heightened the risk of incursions.
Detector dogs are being trained to identify the scent of screwworm larvae and infested wounds. These dogs will work alongside human inspectors at ports and airports, screening livestock imports and exports. The UK’s Animal and Plant Health Agency has expressed interest in the canine component, though no formal partnership has been announced.
For Britain, the primary concern is the potential introduction of screwworm through imported animals or contaminated materials. The agency maintains a contingency plan that includes surveillance, movement restrictions, and the availability of veterinary treatments. Officials have stated that enhanced monitoring is a precaution, not a response to any active threat.
The US programme has drawn attention from international agricultural bodies, including the Food and Agriculture Organization. The combination of sterile insect release and canine detection represents an integrated pest management approach that could serve as a template for other countries. However, critics question the scalability of the dog training component and the long-term cost of maintaining sterile fly production.
Both nations share a mutual interest in protecting agricultural sectors worth billions of pounds. The UK exported over £1.5 billion in live animals and animal products in 2023, and an outbreak would disrupt trade agreements and cause significant economic damage. The agency’s monitoring includes reviewing US data on fly populations and dog field trials.
The US Department of Agriculture has not set a timeline for full deployment, but pilot programmes in Texas and Florida are expected to begin within the next 12 months. The British agency will continue its assessment and may seek bilateral cooperation if the methods prove effective.
