The U.S. Department of Agriculture said Wednesday it had confirmed the first detection of the flesh-eating New World screwworm parasite in American wildlife, found in an elk on a game ranch in Pecos County, Texas, after the animal was harvested by a hunter and reported to authorities.
The finding marks a troubling expansion of a pest that U.S. officials had worked for decades to eradicate from American soil before its unwelcome return earlier this year, when the first new domestic cases in more than two decades were confirmed in livestock in South Texas and New Mexico. Until now, officials had tracked the parasite's spread primarily through cases in cattle, goats and a dog, with wildlife infestations considered possible but unconfirmed — and harder to monitor, since wild animals are not examined as routinely as livestock.
A Parasite That Targets Living Tissue
New World screwworm flies lay eggs in open wounds on warm-blooded animals, and the larvae that hatch feed on living tissue rather than dead flesh, a trait that can turn even minor cuts into serious, potentially fatal infestations if left untreated. The parasite poses a particular threat to the cattle industry, and its reappearance in the U.S. earlier this year prompted authorities to establish quarantine zones, expand surveillance and trapping efforts, and accelerate the release of sterile screwworm flies — a decades-old eradication technique that works by flooding affected areas with lab-raised, reproductively sterile males to crash the wild population's breeding rate.
The USDA is urging hunters, ranchers and wildlife managers across Texas to inspect animals for wounds showing signs of infestation and to report suspected cases promptly, warning that undetected spread through wildlife populations could complicate eradication efforts that have otherwise made progress since the parasite's return this year. Officials said the elk case does not necessarily indicate a wider outbreak in wildlife, but it does confirm that the parasite can establish itself outside of livestock settings — a scenario eradication officials had hoped to avoid.