USDA Confirms First New World Screwworm Detection in Texas Elk

The U.S. Department of Agriculture announced Wednesday that it has confirmed the first detection of the New World screwworm parasite in wildlife in the United States, finding the organism in an elk harvested on a game ranch in Pecos County, Texas. The Texas Animal Health Commission will adjust a previously established infested zone, and the USDA together with the Texas Parks and Wildlife Department are expanding wildlife surveillance in the region.

"We encourage all hunters and landowners to be vigilant for signs of New World screwworm while they are out in the field this season," Texas wildlife division director Alan Cain said in a statement.

The parasite, eradicated from the United States decades ago, has been moving northward from Central America through Mexico, prompting a more than year-long ban on Mexican cattle imports. Although the United States halted livestock imports from Mexico last year to block the pest, trade resumed in August at an Arizona port as part of a phased reopening plan. The import suspension has tightened U.S. cattle supplies and contributed to record-high beef prices for consumers.

Earlier in June, a calf in Zavala County, Texas, near the U.S.–Mexico border tested positive for screwworm, and dozens of additional cases have been reported this year in animals such as a horse and a dog.