U.S. agriculture officials confirmed that a second case of the New World Screwworm was detected in Texas on Friday. The first domestic case of the larvae was discovered in Zavala County roughly 100 miles southwest of San Antonio on Wednesday, after months of a rising number of cases in northern Mexico worried cattle farmers and Texas agriculture officials. A second case — roughly 5.6 miles from the first one — was confirmed Friday in a 1-month-old calf, the USDA said in a news release.
The parasitic flies lay eggs in open wounds and feed on living flesh, causing damage — and often, death — to livestock. In rare cases, the maggots can infect humans. They pose a threat to the state’s $17 billion cattle industry, which produces more beef than any state in the U.S. The flies can also infest any warm-blooded animals, including wildlife and pets.
A federal response team collected samples to look for any additional screwworm cases in Zavala County near where the second case was detected, and they all came up negative, the USDA said. Once widespread across the southern United States, the flies were eradicated domestically in the 1960s. The USDA said the cases detected this week are the first in Texas since 1966. As of Wednesday, officials had reported more than 171,700 animal cases and more than 2,070 human cases in Mexico and Central America.
Federal and state officials are releasing hundreds of thousands of sterile flies to try and stop the spread — a strategy meant to have sterile males mate with females so their eggs never hatch into the flesh-eating maggots that infect livestock. Female flies only mate once in their weekslong adult lives.