An invasive parasite is reportedly heading toward the United States, following the same land corridor through South and Central America that more than a million migrants have used to reach the southern border in recent years. Now, the U.S. government is intervening in an effort to halt the advance of the New World screwworm before it enters American territory.
Darien Gap becomes parasite’s pathway
The Darien Gap — a rugged stretch of land connecting Colombia and Panama — is the only land route between South and North America. More than 1.2 million migrants crossed through the Darien between 2021 and 2024, according to data from Panamanian officials.
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Among the travelers, authorities say, was the New World screwworm.
Agriculture secretary announces response plan
Secretary of Agriculture Brooke Rollins announced the large-scale initiative targeting the parasite at a recent news conference in McAllen, Texas.
“That’s why we’re here in McAllen, Texas, to announce a bold new initiative that addresses the deadly parasite called the New World screwworm,” Rollins said. “It would devastate ranchers who raise our cattle, sheep, goat and horses — especially if it made its way across the border.”
Rollins said planes will drop millions of sterilized male screwworms over known infestation zones abroad. The effort aims to prevent the parasite from reproducing and spreading northward.
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The Darien Gap, the only land route between South and North America, saw 1.2 million migrants pass between 2021 and 2024.
Strategy mirrors previous successful eradication effort
The method mirrored a successful campaign from 1982 when the screwworm was officially eradicated from Mexico using sterile fly drops, as well as successful efforts in the U.S. that led to the screwworm’s eradication in 1966. For decades, the U.S. has worked in partnership with Panama to maintain buffer zones and prevent re-infestation.
However, U.S. officials have now told Newsweek that increased human and animal traffic through the Darien Gap is elevating the risk again.
US announces plan to combat screwworm spread
The U.S. Department of Agriculture is allocating $8.5 million to construct a sterile fly dispersal site at a former Air Force facility in Texas. Officials say the site will be operational within six months.
An additional $20 million will go toward expanding output at existing dispersal facilities in Mexico.
To help contain the spread, U.S. ports of entry have been temporarily closed to live cattle arriving from Mexico. However, Rollins said some ports may reopen “in upcoming weeks” if containment efforts prove effective.
Parasite poses danger to animals and humans
The screwworm is a flesh-eating fly that primarily targets livestock and wildlife. Its larvae are known to burrow into open wounds of living animals. While rare, human infections do occur, with deaths reported in Costa Rica and Honduras this year.
As of now, officials report that the flies have been detected as far away as 700 miles from the Texas border.
