Judy McCullough, a rancher in Wyoming, still remembers the blood sprayed on the barn walls, the smell of burning tar and the fear of finding a maggot nestled in the broken hide of a cow.
More than 70 years ago, when Ms. McCullough was a child on her grandfather’s cattle ranch, the new world screwworm was all but certain to incite dread. Feeding on the flesh of the live cattle, it laid eggs on open wounds, killing the animals if it went untreated.
Ranchers resorted to a number of preventative measures: spraying noxious pesticides, dehorning and castrating calves in colder months that screwworm larvae could not survive, and branding using a tar mixture to minimize open flesh.
“Nothing’s nastier than this maggot,” Ms. McCullough, 79, said, recalling the aftermath of a gory dehorning. She pointed to the care that people “took of wounds, even on themselves,” given that the fly could be equally deadly to humans.
Since the 1970s, the screwworm has largely stayed out of the United States, kept at bay by an eradication campaign that has prevented the large-scale loss of livestock and wildlife and saved the cattle industry $2.3 billion a year, according to one government estimate. But after breaching a biological barrier in Panama in 2022, the flesh-eating parasite is at risk of returning, spurring the United States and Mexico to invest in increased biological countermeasures, surveillance, detection and scientific research.
The efforts reflect a scramble to address a potentially lethal threat whose spread could have wide-ranging ramifications. The cattle industry already faces high feed prices, drought and consolidation. And because the screwworm’s appetite is not limited to beef, its return could infect other farmed animals, wildlife like deer and rabbits, pets and even people.
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The post Gene Editing and Fly Factories: The Fight Against a Flesh-Eating Pest appeared first on New York Times.
