AUSTIN, TX — Agriculture officials are on high alert as a terrifying, flesh-eating parasite has been detected just miles from the Texas-Mexico border. The return of the New World screwworm, a pest once eradicated from North America, is being described by officials as a “flashing red warning sign” for the nation’s livestock industry.
Earlier this week, the U.S. Department of Agriculture (USDA) confirmed active cases of the screwworm in the Mexican state of Nuevo León. Texas Agriculture Commissioner Sid Miller noted that one infected calf was discovered only 62 miles from the border—the northernmost active case recorded to date.
What is the New World Screwworm?
The New World screwworm is not a typical fly. Unlike most maggots that feed on dead tissue, screwworm larvae feed on the living flesh of warm-blooded animals and, in rare cases, humans.
According to the Centers for Disease Control and Prevention (CDC), the infection process is gruesome:
- The Strike: A female fly lays eggs in an open wound, which can be as small as a tick bite, or in an animal’s eyes, nose, or mouth.
- The Infestation: The eggs hatch into larvae (maggots) that burrow deep into the living tissue to feed, creating foul-smelling, painful wounds.
- The Cycle: After feeding for several days, the larvae drop to the ground, burrow into the soil, and emerge as mature flies to start the cycle again.
The Economic Threat to Texas
Texas is home to the largest cattle industry in the United States, and the reemergence of this parasite could be catastrophic. While the USDA currently maintains there is no immediate risk to American livestock, pets, or people, officials aren’t taking any chances. Southern ports of entry have been closed to livestock trade to prevent the parasite from crossing the border.
A recent study published in the journal Nature suggests that climate change is playing a role in the fly’s northward march. Hotter temperatures and shifting weather patterns are creating “favorable conditions” for the flies to thrive in Texas and other southern states. If the screwworm becomes established in the U.S. again, economic losses could soar into the billions of dollars.
A History of Eradication
The United States was declared free of indigenous screwworms in 1966, thanks to a massive biological program. Scientists used a “sterile insect technique,” releasing millions of sterilized male flies to crash the wild population. By the early 2000s, the pest was considered eradicated from North America.
Aside from a small, isolated outbreak in the Florida Keys in 2017, the U.S. has remained largely screwworm-free for decades. However, the steady northward movement from endemic regions in South and Central America now threatens that status.
What Residents Should Watch For
While the risk to humans is low, pet owners and ranchers are urged to be vigilant. Any open wound on an animal should be treated and monitored. Signs of infestation include:
- Wounds that do not heal or emit a foul odor.
- Visible movement of larvae within a wound.
- Animals appearing distressed or lethargic.
What do you think, Texas? Are you concerned about the return of this parasite, or do you trust the border closures to keep our livestock safe? Share your thoughts in the comments below.
