USDA Confirms New World Screwworm in Texas Calf, Launches Quarantine and Sterile-Fly Response

U.S. Department of Agriculture confirmed a case of New World screwworm in a three-week-old calf in Zavala County, Texas, on Wednesday night. U.S. infection since the parasite was eradicated in the 1960s.

A sample from the calf was sent to the National Veterinary Services Laboratories in Ames, Iowa, for confirmatory testing. Agriculture Secretary Brooke Rollins posted that the testing had confirmed the infection. The USDA is establishing a unified Incident Command Team with the Texas Animal Health Commission and sending response personnel to the area.

Officials have created a 20-kilometer quarantine, movement-restriction, and increased-surveillance zone around the detection site. The agency will release sterile flies through ground-release chambers near the site. Four million sterile flies were already being released by air in the area this week.

Earlier detections occurred in Mexico. On May 28, a case was found in a five-year-old goat in Coahuila, 25 miles from the border. Another case was identified in a calf 39 miles from the border, also in Coahuila.

-Mexico border. It is constructing a $750 million sterile-fly production facility in South Texas. The screwworm biological barrier at the Darién Gap was breached in 2022. Screwworms were declared eradicated from Panama in 2006.

State representative Don McLaughlin posted on social media that a case had been found one mile from the Texas border. Reuters reported that McLaughlin suspected the fly was now in the United States. McLaughlin said samples were taken Tuesday from two calves on a ranch in La Pryor, Texas, in Zavala County.