A parasitic fly that feeds on living flesh has been detected in cattle in Texas, marking the first cases in the United States since the 1960s. The New World screwworm, eradicated from the country decades ago, has triggered an aggressive federal and state response aimed at preventing further spread.
The first case was confirmed in a three-week-old calf with an umbilical lesion in Zavala County, southwest of San Antonio. A second infection was discovered days later in a one-year-old calf approximately five miles away. The Texas Animal Health Commission established an infested zone in the area and implemented animal movement restrictions to contain the parasite.
The New World screwworm is a parasitic larva that burrows through the living flesh of warm-blooded animals and humans, causing a painful condition called myiasis. If left untreated, the infection can be fatal to infected animals.
Texas Governor Greg Abbott issued a statewide disaster declaration in response to the outbreak. "We're in the season for spread," Abbott warned, predicting an "extraordinarily challenging summer" for affected areas. State officials are coordinating with the federal government to slow the parasite's expansion.
The response includes releasing millions of sterile screwworm flies near the infection sites. These sterile male flies cannot reproduce with wild females, which prevents the population from expanding. The U.S. Department of Agriculture has deployed teams and is testing suspect cases to identify additional infections. Officials emphasized that this combination of sterile fly release, enhanced surveillance, movement restrictions, prompt wound treatment, and public education represents a proven and effective control strategy.
The Texas Animal Health Commission had spent more than two years preparing for a potential resurgence of the parasite. "We are putting these preparations into action, and we encourage all animal owners and caretakers to continue to remain vigilant for the presence of larvae in animal wounds and immediately report any suspicions," said commission director Dr Bud Dinges.
A widespread outbreak could significantly impact the U.S. cattle industry. The country has faced economic pressures since the disease appeared in Central America more than a year ago. The U.S.-Mexico border has been closed to live cattle imports during this period, shrinking the roughly 100 billion dollar beef industry to a 75-year low. The United States formerly imported more than one million cattle annually from Mexico, representing approximately 4 to 5 percent of all cattle sold for beef production.
Canada's food inspection agency announced a temporary ban on livestock from Texas, prohibiting cattle and horses that were in the state within 21 days before crossing the border. Though officials noted the parasite is unlikely to establish itself in Canada's colder climate, they warned farmers to monitor livestock for wounds accompanied by discharge or foul odor.
The USDA confirmed that the U.S. food supply remains safe, as the screwworm does not infest meat, fruits, vegetables, or other food sources.