Deadly cattle parasite resurfaces in Texas as officials debate responsibility while a billion-dollar response plan is launched to protect livestock industry
A growing livestock health crisis is unfolding in the United States as the New World screwworm parasite re-emerges in Texas, triggering both a major federal response and a heated political blame game.
US Agriculture Secretary Brooke Rollins recently visited affected ranches in Texas, where early cases of the parasite were detected in cattle. During her visit, she also observed the release of sterile flies, a long-used biological control method aimed at stopping the parasite’s reproduction cycle.
However, the outbreak has quickly turned political. Rollins blamed the return of the parasite on policies from the Biden administration, while Democratic leaders argue that budget reductions in agricultural programs under former President Donald Trump weakened prevention systems.
What makes screwworm dangerous?
The New World screwworm is a parasitic fly whose larvae infest open wounds of warm-blooded animals, feeding on living tissue rather than dead flesh. Infected animals can suffer severe injury and, in untreated cases, death—posing a serious threat to livestock industries.
Experts stress that while it does not affect food safety, its impact on animal health and productivity can be economically devastating.
A billion-dollar response underway
To contain the outbreak, the US Department of Agriculture (USDA) is preparing an aggressive national response strategy expected to exceed $1 billion.
A key component includes the construction of a large-scale facility capable of producing up to 300 million sterile flies per week. This method works because female screwworm flies mate only once—if they mate with a sterile male, the eggs do not hatch, gradually collapsing the population.
Spread linked to climate and geography
Scientists warn that the parasite, once eradicated in North America for over 60 years, is now reappearing after crossing from Central America, where it had been contained near Panama for decades.
Experts say warmer temperatures are likely contributing to its spread. Screwworms thrive in humid environments above 25°C, and climate conditions are increasingly expanding suitable habitats further north.
Seven cases have already been confirmed in Texas and New Mexico, leading to quarantine zones around affected areas.
Global impact and trade disruption
The outbreak has already disrupted livestock trade across North America:
- Mexico has reported over 28,000 cases in recent years
- The US previously restricted livestock imports from Mexico
- Canada has temporarily halted imports of cattle and horses from Texas
While authorities believe the situation can still be contained, experts warn that failure to act quickly could turn it into a billion-dollar international livestock crisis.
Unanswered scientific questions
Despite decades of control success using sterile fly programs, scientists are still unclear why the screwworm re-emerged after being largely eliminated. Experts emphasize that immediate containment, international cooperation, and expansion of sterile fly production are critical to pushing the parasite back toward its previous containment zone in Panama.
