PerspectiveAmerica’s Never-Ending Battle Against Flesh-Eating Worms

Screwworms once killed millions of dollars’ worth of cattle a year in the southern U.S. Their range extended from Florida to California, and they infected any living, warm-blooded animal: not only cattle but deer, squirrels, pets, and even the occasional human. Sarah Zhang writes in The Atlantic that, in fact, the screwworm’s scientific name is C. hominivorax or “man eater”—so named after a horrific outbreak among prisoners on Devil’s Island, an infamous 19th-century French penal colony in South America.

She adds:

For untold millennia, screwworms were a grisly fact of life in the Americas. In the 1950s, however, U.S. ranchers began to envision a new status quo. They dared to dream of an entire country free of screwworms. At their urging, the United States Department of Agriculture undertook what would ultimately become an immense, multidecade effort to wipe out the screwworms, first in the U.S. and then in Mexico and Central America—all the way down to the narrow strip of land that is the Isthmus of Panama. The eradication was a resounding success. But the story does not end there. Containing a disease is one thing. Keeping it contained is another thing entirely, as the coronavirus pandemic is now so dramatically demonstrating.

To get the screwworms out, the USDA to this day maintains an international screwworm barrier along the Panama-Colombia border. The barrier is an invisible one, and it is kept in place by constant human effort. Every week, planes drop 14.7 million sterilized screwworms over the rainforest that divides the two countries. A screwworm-rearing plant operates 24/7 in Panama. Inspectors cover thousands of square miles by motorcycle, boat, and horseback, searching for stray screwworm infections north of the border. The slightest oversight could undo all the work that came before.

The insect is relentless in its search for hosts. Those who fight it must be relentless too.