The United States has shut its southern border to livestock imports amid rising alarm over the spread of the New World screwworm fly in Mexico a flesh-eating parasite that once devastated American agriculture and is now inching closer to Texas.
The parasite, notorious for its larvae that infest and consume the flesh of warm-blooded animals, has re-emerged in northern Mexico. Although Mexican authorities argue that the situation is under control with confirmed infestations down 19% since late June U.S. officials remain wary of the potential economic fallout should the screwworm cross into American livestock regions.
To counter the threat, the U.S. Department of Agriculture has allocated $30 million to intensify efforts to breed and release sterile male screwworm flies. This well-established technique interrupts reproduction cycles and aims to gradually wipe out the fly population.
Additionally lawmakers have urged the fast-tracking of treatment approvals pointing to current restrictive labeling regulations that are slowing down access to effective anti-parasitic medications.
While the border closure has drawn criticism from Mexican President Claudia Sheinbaum, who labelled the response as excessive, U.S. officials defend it as a necessary precaution. The screwworm’s return threatens not only livestock but also wildlife and even humans in rare cases, making rapid containment a top priority.
The situation has reignited memories of the costly and lengthy eradication campaign in the mid-20th century, which successfully eliminated the parasite from the U.S. by 1982. With the parasite now on the move again, vigilance and cross-border cooperation will be critical to preventing a new agricultural crisis.