Flesh-eating parasite New World screwworm confirmed in Texas, USDA says

New World screwworm, a parasitic fly that eats warm-blooded animals alive, has been found in a calf in Texas, the U.S. Department of Agriculture said on Wednesday evening, exposing the nation's cattle herd to a serious new threat.

A case was confirmed in a calf in La Pryor, Texas, a town about 30 miles (48 km) northeast of the U.S.-Mexico border - a blow to U.S. cattle ranchers who have been bracing for a domestic screwworm outbreak as the pest has advanced north through Mexico over the past year.

USDA Secretary Brooke Rollins said the case, the first in Texas since 1966, was the only confirmed infestation in the country.

The pest could further shrink the U.S. cattle herd, which is at its lowest level in 75 years. Tight supplies have already reduced beef production and driven prices to record highs for consumers.

The detection also threatens Texas' livestock industry, which could face up to $1.8 billion in estimated economic losses if the pest spreads, and represents a setback for U.S. efforts that cost millions of dollars to keep the pest out, experts said.

Reuters reported on Wednesday morning that samples of a suspected screwworm infestation at a ranch in La Pryor had been sent for testing to the federal government's lab in Ames, Iowa. Chicago Mercantile Exchange feeder cattle futures FCQ26 extended losses, ending 1.7% lower, with traders worried that confirmation of a U.S. case may reduce demand for beef.

Screwworms are parasitic flies whose females lay eggs in open wounds and mucous membranes on any warm-blooded animal. Once the eggs hatch, hundreds of screwworm larvae use their sharp mouths to burrow through living flesh, eventually killing their host if left untreated. They mostly spread through the movement of infested animals.

The fly can infest people and pets as well, but the risk to humans is low and human cases of screwworm are rare, experts said. The fly poses no food safety issues.

Production: Jose Pablo Diaz/Reuters