Flesh-eating screwworms detected in Texas calf

In La Pryor, Texas, a three-week-old calf was found with larvae in its umbilical area, confirming the first US case of flesh-eating New World screwworm since 1966. This detection ends a period of eradication that had lasted nearly six decades. The re-emergence signals that flesh-eating screwworms are entering US territory in 2026, posing a direct threat to livestock and public health.

The United States had believed it permanently eradicated the New World screwworm decades ago, prior to its re-emergence. This confirmed case in Texas proves that even long-defeated parasites can breach national borders, challenging established biosecurity protocols.

Without swift and comprehensive action, the re-established screwworm population could severely impact the US cattle industry and potentially human health, reversing decades of eradication efforts.

How Do Screwworms Threaten US Cattle?

• The New World screwworm fly has been detected in south Texas, marking the first time in decades it has threatened the U.S. cattle industry, according to PBS.
• US agriculture and health officials have outlined a plan to combat the flesh-eating parasite, the New World Screwworm, which has been detected in the US for the first time since 1966, states BBC.

The rapid outlining of a combat plan by US officials underscores the serious economic threat this parasite poses to the vital cattle industry in Texas and beyond. Companies in the US cattle industry, having operated for nearly 60 years without this threat (PBS), are now facing an immediate and costly biosecurity challenge that could rapidly escalate without aggressive, coordinated intervention.

How Did Screwworms Re-Enter the US?

The sterile fly barrier at the Darién Gap was breached in 2022, according to arstechnica. This critical containment barrier provides a plausible route for the re-introduction of the screwworm into previously eradicated zones. The 2022 breach of the Darién Gap sterile fly barrier (arstechnica) reveals that the US's decades-long eradication success (BBC) has fostered a dangerous complacency, leaving the nation vulnerable to pathogens that were believed to be permanently defeated.