The U.S. Department of Agriculture confirmed the first domestic case of the New World flesh-eating screwworm in a Texas calf [1].
The reemergence of this destructive parasite threatens the U.S. cattle supply for the first time in decades. Because the parasite attacks living tissue, it can cause severe injury or death to livestock if not treated immediately.
USDA Secretary Brooke Rollins said the parasite was detected in a three-week-old calf [2] located in Zavala County, Texas [3]. The discovery has prompted federal authorities to implement emergency quarantine and control measures to prevent the parasite from spreading further into the interior of the country.
Rollins said the agency is focusing its efforts on the border region. "It's really south Texas where we're really combatting this every day," Rollins said.
Federal officials said the parasite had previously been detected in Mexico within 25 miles [4] of the U.S. border. The USDA announcement regarding the domestic case was made on June 3, 2024 [5].
To combat the spread, the government is investing in a multi-million dollar sterile-fly facility [6]. This biological control method involves releasing sterile male flies into the wild to disrupt the breeding cycle of the parasite. This strategy was used in previous decades to successfully eradicate the New World screwworm from the U.S. mainland.
Currently, only one case has been officially detected within the U.S. [1]. Agriculture officials continue to monitor livestock in the South Texas region to ensure the infestation remains contained.
“"It's really south Texas where we're really combatting this every day."”
The reappearance of the New World screwworm represents a significant biosecurity breach. Because the parasite can devastate livestock populations and impact meat production, the USDA is reverting to aggressive biological warfare—specifically the sterile-fly technique—to prevent a wider agricultural crisis along the southern border.
