For the first time in nearly a decade, a deadly cattle parasite has been confirmed in the United States, threatening a livestock herd already at its smallest size in 75 years. The U.S. Department of Agriculture announced late Wednesday that a suspected case in South Texas tested positive for the New World screwworm, a pest capable of killing an animal within days.
First detection since 2016
The screwworm was last detected in the U.S. in 2016 among deer in the Florida Keys, and it was eradicated by 2017. The current case involves a three-week-old calf in Zavala County, Texas, which is the only case being tracked by the agency, according to Agriculture Secretary Brooke Rollins. The USDA has implemented quarantines, movement controls, and surveillance in a 20-kilometre zone around the detection, and has expedited the release of sterile flies to prevent the pest's spread.
Impact on cattle industry
Zavala County, though not in Texas's main cattle production areas, has a prominent livestock industry with over 38,000 cattle as of 2022. The detection comes at a dire time for the U.S. beef and cattle industry, as a smaller herd has already pushed consumer prices to record highs. Shares of Tyson Foods Inc. and JBS NV rose in premarket trading Thursday after falling the previous day on unconfirmed reports of the infection. Feeder and live cattle futures in Chicago both declined Wednesday.
Corbitt Wall, a livestock market analyst at DV Auction, noted that the primary risk is to livestock, not meatpackers or consumers, as most calves are still on pasture and not being sold. While the detection could support cattle prices by threatening supply, it also gives consumers pause, Wall said. The USDA stated that the food supply remains safe, as screwworm does not infest meat or other food sources.
Government response
Agriculture Secretary Rollins expressed confidence that the pest will not become established in the U.S. Senate and House Agriculture Committee Chairmen John Boozman and GT Thompson called for a full deployment of the government's response plan, emphasizing that the case should not cause panic. The U.S. has been preparing for months, pausing imports of live Mexican cattle and building facilities to disperse sterile flies. However, screwworm cases in Mexico have recently accelerated, with the closest detection in a goat about 25 miles from the U.S. border.
Broader implications
The screwworm's presence in Mexico and the halt to live cattle trade have exacerbated supply tightness for U.S. meatpackers, who face operational losses from fewer and costlier animals. This shortage has sent consumer beef prices to all-time highs, challenging President Donald Trump's promise to ease grocery prices. The USDA's previously prepared plan includes movement restrictions for animals in and out of an infested zone in the event of a localized outbreak.
