Gov. Greg Abbott of Texas said on Friday that the state is working with the federal government to slow the spread of the New World screwworm days after the first case was detected in the United States in decades.
Later in the day, the U.S. Department of Agriculture said that a second case had been confirmed, this time in a one-month-old calf. The cases are about five miles apart in Zavala County, southwest of San Antonio. The second case was anonymously confirmed by an official with the Texas Animal Health Commission who was not authorized to speak publicly. The calf is being treated, the official said.
Mr. Abbott said in a press briefing Friday that Texas, led by the U.S.D.A., is dispersing millions of sterile male New World screwworm flies that would prevent wild female flies from producing offspring and gradually drive the population toward eradication. He also signed a statewide disaster declaration to ensure that the affected areas received resources ahead of what he said is likely to be “an extraordinarily challenging summer to get through this.”
“We’re in the season for spread,” he said.
The move comes two days after the U.S.D.A. confirmed the first case of screwworm since the 1960s in a three-week-old calf in La Pryor, Texas, a rural ranch area 97 miles southwest of San Antonio. The screwworm is a fly whose larvae feed on the tissue of livestock, wildlife and pets that has long been eradicated in the country.
The news unnerved the cattle and beef industries in Texas, long considered the heart of the American beef industry. Texas leads the nation in beef production, with more than 4.1 million cattle, and accounts for about 15 percent of beef production in the United States, according to the Texas Agriculture Department.
Even before the confirmed case in Texas, the beef industry was facing its fair share of challenges. The American cattle inventory has diminished to its lowest levels since 1952 partly due to persistent droughts and high feed prices. Domestic beef prices continue to climb to record highs.
The screwworm had been eradicated by the mid 2000s from all of North and Central America. But the parasite resurfaced in 2024 after it was detected along Mexico’s border with Guatemala. More than 20,000 cases have been detected in Mexico alone in recent years resulting in the United States barring the entry of all Mexican cattle for more than a year.
In recent days, Sid Miller, the Texas Agriculture Commissioner, accused the federal Agriculture Department of dismissing his concerns of a possible screwworm infestation.
“Instead of using every available tool, U.S.D.A. moved too slowly and relied solely on a partial solution that takes years to fully implement,” he said in a statement.
The infected calf in La Pryor, Texas, is being treated and making progress, said Lewis R. Dinges, the executive director with the Texas Animal Health Commission.
“We are doing any and all things possible to stop the spread of New World screwworms as we speak,” Mr. Dinges said.
Infestations occur after a female fly lays eggs, some 10 or 400 at a time, on a fresh wound. It can take just a few hours for the eggs to hatch into larvae that burrow and feed on the flesh. An open wound attracts more flies, which in turn lay more eggs. An infection can kill a cow within two weeks if left untreated.
Mr. Abbott also urged for production of more sterile flies to increase “as quickly as possible.” The Army Corps of Engineers recently broke ground on a $750 million production facility at Moore Air Base in Edinburg, Texas, in hopes of controlling the pest in the future. The facility is expected to start producing 100 million sterile flies per week in late 2027, and later increase that figure to 300 million per week. One such facility in Panama, the only one of its kind, produces about 100 million such sterile flies weekly. Those are transported to Mexico and the United States.
In addition, the Agriculture Department moved to declare a 12-mile “infested zone” quarantine area where the infected calf was found. The agency also increased surveillance and limited the movement of all warm-blooded animals. The department and the Texas Animal Health Commission have deployed veterinarians and animal health officials to the affected region.
State officials and the Agriculture Department said that the federal Food Safety and Inspection Service will ensure that all beef, poultry and eggs are safe to eat. Screwworm flies do not move very far and do not infest fruit or vegetables, but they spread with the transportation of unknowingly infected animals.
It is unknown how the calf in Texas was infected. In the past, officials have said that illegal livestock transport and warm weather patterns have contributed to the worm’s climb north. Wild animals like deer and pets can also be infected.
Mr. Abbott urged averaged Texans to “check your animals daily,” and report any suspected cases to the state.
“This is a highly treatable condition if acted on quickly,” he said.
