Federal authorities have confirmed a second case of the New World screwworm in Texas, triggering an emergency response that includes the release of millions of sterile flies designed to halt reproduction of the parasite. The infections, discovered in Zavala County southwest of San Antonio, mark the first detection of the flesh-eating pest in the United States since the 1960s.
Governor Greg Abbott issued a statewide disaster declaration Friday, warning that the coming months will be "an extraordinarily challenging summer" for affected areas. State officials are coordinating with the USDA and the Texas Animal Health Commission to contain what amounts to the parasite's first documented resurgence in the continental US after creeping northward from Central America over the past year.
The first confirmed case involved a three-week-old calf with an umbilical lesion. The second was discovered days later after USDA officials tested multiple suspect cases in the region. Both infections were found roughly five miles apart in the same county, prompting officials to establish an infested zone and implement animal movement restrictions to prevent further spread.
The screwworm fly lays eggs that hatch into larvae capable of burrowing through living flesh. If left untreated, the infestation can prove fatal to livestock and other warm-blooded animals. The condition caused by the parasite, known as NWS myiasis, is characterized by the larvae feeding on tissue and creating painful wounds.
To combat the outbreak, authorities are dispersing millions of sterile male flies throughout the affected area. These flies cannot reproduce but will mate with wild females, disrupting the reproductive cycle and degrading the parasite's ability to spread. The USDA has confirmed that the US food supply remains safe, as the screwworm does not infect meat or produce.
The Texas Animal Health Commission had spent more than two years preparing for such a resurgence. The agency's director, Dr Bud Dinges, urged livestock owners and caretakers to remain vigilant for signs of infestation and report suspected cases immediately. The commission emphasized that a combination of sterile fly releases, enhanced surveillance, movement controls, prompt wound treatment, and public education constitutes a proven eradication strategy.
The detection carries significant economic consequences. The US beef industry, already strained by more than a year of border closures on live cattle imports from Mexico, faces potential losses from animal deaths and increased treatment and labor costs. The sector has contracted to a 75-year low, with imports from Mexico now banned despite historically supplying 4 to 5 percent of all cattle raised for US beef production, or more than 1 million head annually.
Canada's food inspection agency responded swiftly by announcing a temporary ban on livestock from Texas, refusing to accept cattle and horses that entered the state within 21 days of crossing the border. While Canadian officials acknowledged that the parasite is unlikely to establish itself in the country's colder climate, they urged farmers to monitor livestock for wounds and lesions accompanied by discharge or odor.
Author James Rodriguez: "This isn't just a Texas problem anymore, and the timing couldn't be worse for an industry already on its knees from trade restrictions."
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