The U.S. Department of Agriculture confirmed Wednesday that a hunter-harvested elk in Pecos County, Texas, was infected with the New World screwworm, marking the first detection of the parasite in American wildlife during the current outbreak.

The elk was found on a game ranch, and the infestation was identified after the animal was harvested. The discovery prompted federal and state authorities to expand wildlife surveillance in the area and prepare to modify an existing screwworm-infested zone.

New World screwworm is a parasitic fly whose larvae burrow into and feed on the living tissue of warm-blooded animals. The infestation can cause severe, expanding wounds and can become fatal without prompt treatment. Livestock, wildlife, pets, and, in some cases, humans can be affected.

The parasite was eradicated from the United States in 1966 through an extensive sterile-fly program. However, it has been spreading north through Central America and Mexico, prompting renewed efforts to prevent it from becoming established in the U.S.

The wildlife discovery comes amid other recent detections. In June, the USDA confirmed a case in a calf in Zavala County, Texas. On Wednesday, New Mexico authorities also reported a case in a beef cow in Otero County, underscoring the continued threat to livestock and animal health.

Officials are urging hunters, ranchers and landowners to inspect animals carefully and report suspected infestations. Warning signs include maggots in wounds, open or enlarging sores, foul-smelling injuries, unusual weakness, and signs of distress.

Hunters are also being advised to examine harvested animals before field dressing or moving carcasses. Early reporting can help officials identify additional cases and limit the parasite’s spread.

The USDA and Texas Parks and Wildlife Department are continuing surveillance in the affected region as officials work to protect wildlife, livestock, and the broader agricultural industry.