US plans to fight flesh-eating screwworm outbreak with flies and dogs

June 5, 2026

US agriculture and health officials have announced a comprehensive response plan after detecting the New World Screwworm parasite in Texas for the first time domestically since 1966, following its northward spread from Panama through Central America and Mexico. The primary strategy involves releasing sterile flies to prevent reproduction, but current production capacity of 100 million flies weekly falls far short of the estimated 600 million needed to effectively combat the outbreak. Authorities have established a containment zone near the Mexico border where the infected calf was discovered and are implementing quarantines, movement restrictions, and deploying specially-trained detection dogs at border crossings.

Who is affected

Cattle ranchers and the beef industry
A three-week-old calf in La Pryor, Texas (first detected case)
2,070 human cases reported across affected regions
Residents and livestock owners within the 20km control zone near the Mexico border
Pet owners in affected areas
US Department of Agriculture (USDA)
US Centers for Disease Control and Prevention (CDC)
Customs and Border Protection
Government facilities in the US and Mexico producing sterile flies

What action is being taken

Releasing four million sterile flies by ground and four million by plane weekly
Establishing and maintaining a 20km-wide control zone around La Pryor, Texas
Implementing quarantines, movement controls, and surveillance in the control zone
Stationing specially-trained "Beagle Brigade" dogs at borders to detect screwworms
Producing approximately 100 million sterile flies per week at facilities in the US and Mexico

Why it matters

This outbreak represents a significant threat to the US cattle industry and beef markets, as screwworm parasites can kill livestock if left untreated by burrowing through living flesh. The parasite's return after nearly 60 years of absence demonstrates a failure of containment efforts that had successfully pushed the species south of Panama, with the northward expansion attributed to reduced monitoring programs, inadequate international cooperation, and potentially climate change enabling the warm-climate parasites to survive in more northern regions. The current production capacity of sterile flies being only one-sixth of what experts estimate is needed raises concerns that the outbreak could establish itself permanently in the US, reversing decades of eradication efforts.

What's next

Officials plan to scale up production to 600 million sterile flies per week
Ranchers are being instructed to cover wounds on livestock to prevent infestation
People should check themselves and their pets and immediately report any detections to officials

Read full article from source: BBC