The United States spent more than half a century and hundreds of millions of dollars driving the flesh-eating New World screwworm as far from its borders as possible. Now, it’s back.The species can eat the tissue of any warm-blooded animal, but it’s a particular threat to livestock and is often fatal for cattle. Some environmentally minded bioethicists have openly debated whether it would be moral to deliberately drive the screwworm into extinction.“There are some species that it’s worth considering wiping out altogether and I do think the screwworm is one,” said Gregory Kaebnick, a senior research scholar at the Hastings Center for Bioethics.AdvertisementAdvertisementThe Agriculture Department announced Wednesday that the New World screwworm had been found in a calf in Texas — the first detection in U.S. cattle during a natural incursion since 1982. The agency reported a second case Friday. It was discovered about six miles from the first infection. The discovery represents a worrisome comeback for the species and a failure in containment for the U.S., reprising a decadeslong battle the country waged once already.Experts said the U.S. will run much the same playbook as it did starting in the late 1950s, when the government embarked on an aggressive, multinational fight against the screwworm. Because female screwworms only mate once, the strategy is to mass-produce sterile males and release them into the wild, where they serve as reproductive dead ends.“It is a tremendous strategy. It has worked and will continue to work moving forward,” said Chad Cross, a professor of parasitology at the Texas Tech University School of Veterinary Medicine.He added that the new Texas case “is a stark reminder of how quickly we need to act to ensure that it doesn’t spread further.”AdvertisementAdvertisementThe screwworm is not a worm at all, but a species of blowfly native to the southern U.S. The flies are attracted to rotting, unkept wounds. …
