USDA confirms New World screwworm in a Texas elk

Hunters are asked to report visible maggots and suspicious wounds

The U.S. Department of Agriculture and the Texas Parks and Wildlife Department have confirmed the first known case of New World screwworm in U.S. wildlife during the current outbreak. The parasite was found in a female elk harvested in Pecos County, Texas. The case came after the USDA detected the parasite in a calf in early June, leaving farmers concerned about a potential spread among ranches.

The USDA announced the wildlife case Wednesday in a statement. The elk had been harvested by a hunter on a game ranch in Pecos County. The Texas Parks and Wildlife Department said a sample from the elk had been submitted to the USDA Agricultural Research Service’s Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, where the parasite was identified and confirmed.

Texas Parks and Wildlife Department wildlife division director Alan Cain urged field users to remain alert. “We encourage all hunters and landowners to be vigilant for signs of New World screwworm while they are out in the field this season,” Cain said in a statement.

The USDA listed visible maggots in wounds or body openings and foul-smelling injuries among the warning signs. The agency also advised hunters to watch for animals that appear lethargic or weak, infestation around the nose, mouth, ears, eyes or genital areas, and wounds that are open, draining or enlarging.

The USDA asked people in the field to report suspicious signs without delay. “If you see anything suspicious, report it immediately,” the agency said. “Fast reporting helps animal health officials respond quickly and helps limit the pest’s spread.”

The June detection occurred in a calf in Zavala County and was the first finding of New World screwworm in the United States. The elk finding is the first known case in U.S. wildlife during the ongoing outbreak rather than the first U.S. detection overall.

The current outbreak was first detected in Panama and Costa Rica in 2023. Since then, cases in animals and people have been reported across Central America and Mexico.

The United States has been preparing for possible infestations. The Food and Drug Administration has issued emergency use authorizations for drugs intended to prevent and treat New World screwworm among livestock and pets.