US moves to contain screwworm outbreak in Texas after first case in decades

AUSTIN: US federal and Texas state authorities have launched emergency containment measures in South Texas after a calf on a farm near La Pryor was found infested with screwworm, the first confirmed case in Texas since 1966.

US Agriculture Secretary Brooke Rollins said on Thursday that no additional infestations had been found in cattle or any other animals near the confirmed case. Officials responded by halting animal movement within a 20-kilometre, or 12.4-mile, zone around the site and introducing further controls aimed at stopping the parasite from spreading.

Roads leading out of La Pryor have been fitted with flashing orange signs directing vehicles carrying livestock to stop at checkpoints, where sheriffs and state personnel are inspecting animals for symptoms of screwworm. Speaking to reporters, Rollins said the US Department of Agriculture believed the outbreak could be contained.

"If we all work ​together and follow these treatment and movement restriction guidelines, there is no reason to believe that this incursion will result in any sort of establishment of the pest on our side ​of the border."

Rollins had also told US lawmakers earlier that the USDA considered the case manageable and said screwworm does not pose a food safety threat.

Economic concerns and market reaction

The discovery has raised concerns in the cattle market, with traders warning that a broader outbreak could put additional pressure on the US cattle herd, already at its lowest level in 75 years, and weaken consumer demand for beef. Feeder cattle futures on the Chicago Mercantile Exchange fell initially on Thursday on fears about market fallout, before rebounding by more than 3%.

Texas’ livestock industry could face estimated losses of as much as $1.8 billion if screwworm were to spread widely. Matt Wiegand, a commodity broker at FuturesOne, said the scale of the market impact would depend on how quickly the parasite spreads and how consumers respond.

"We're going to need to see how fast it spreads and how the consumer reacts."

He added:

Until we see a big demand impact from the consumer side, (cattle) numbers are still tight.

US cattle supplies have been shrinking after prolonged drought increased feeding costs and forced ranchers to reduce herd sizes. That contraction has made it harder for processors including JBS, Cargill and Tyson Foods to secure enough animals for their beef plants.

The Meat Institute, which represents meat processors, called on the USDA to consider allowing what it described as low-risk livestock shipments for slaughter, even after the agency froze animal movement in the area around the case. The group said that could include animals sent directly to slaughter from farms that are not infested.

How screwworm spreads

Screwworms are parasitic flies whose females deposit eggs in open wounds and mucous membranes of warm-blooded animals. After hatching, the larvae burrow into living tissue and can eventually kill the host if treatment is not provided.

Nate Sheets, a Republican nominee for Texas agriculture commissioner, described the threat in stark terms.

"The New World screwworm sounds like something from a horror movie, but it's real."

"It is an agricultural emergency."

The USDA has spent millions of dollars trying to keep the pest out of the United States and has already blocked imports of Mexican livestock for more than a year. Rollins said US ports of entry would stay closed to Mexican livestock until further notice.

Despite that, Lee Haines, an associate research professor of biological sciences at the University of Notre Dame in Indiana, said the infestation showed the flies had entered the United States and would spread through wildlife populations. He said the burden would fall most heavily on farmers who must keep watch over animals spread across large, open rangeland where they may go unchecked for days.

Screwworm was eliminated from the United States in the 1960s through the release of large numbers of sterilised male flies, which mate with wild females and produce infertile eggs. US officials said they are again releasing sterile flies both on the ground near the infected site and from the air. Dudley Hoskins, a USDA undersecretary, said authorities were intensifying those efforts in the affected area.

"We are really flooding the zone in this impacted area."