Archive · 5 Sep 2026
Horse Smuggling Exposes Gaps in U.S. Screwworm Defenses
Screwworm is a parasite whose larvae eat the flesh of animals.
It has appeared again among animals in the United States after being absent for decades.
Some horses and other animals are being moved secretly across the Mexico-U.S.
border.
These animals do not receive the normal health checks that legal imports receive.
That means sick animals could cross without anyone noticing.
Officials have not proven that smuggled animals caused any U.S. screwworm cases.
However, scientists say they could help the parasite travel faster.
Police say cartels use the same remote routes to move animals, drugs and people.
The disease could seriously harm ranchers and the wider Texas economy.
Texas deputies intercepted six horses that had crossed illegally from Mexico near Redford in late May.
Smuggled horses and other animals bypass required veterinary inspections, health certifications and quarantine measures.
The United States has confirmed 48 screwworm cases, but officials have not linked any to animal smuggling.
Mexico has reported more than 2,000 equine screwworm cases since its outbreak began in 2024.
Experts warn undocumented animal movements could accelerate disease spread, while a widespread Texas outbreak could cost up to $1.8 billion.
- Who
- U.S. border authorities, local law enforcement, animal-health officials, researchers and smugglers moving horses and other animals.
- What
- Illegal animal trafficking is continuing across parts of the Mexico-U.S. border, creating a possible pathway for New World screwworm to spread.
- When
- A six-horse interception occurred in late May; Reuters reported the investigation on September 5, and Mexico's outbreak began in 2024.
- Where
- Remote stretches of the Texas-Mexico border, including Redford, Presidio County, Zapata County and Terrell County.
- Why
- Smuggled animals avoid veterinary inspections, certifications and quarantine measures, while trafficking offers financial opportunities and supports other cartel activities.
Disease-risk concerns
Evidence and enforcement limits
Could smuggling spread screwworm?
Disease-risk concerns
Researchers and animal-health experts say undocumented crossings can move infected animals faster than the parasite would travel naturally because the animals avoid inspections and treatment.
Evidence and enforcement limits
U.S. officials have not linked any of the 48 confirmed U.S. cases to smuggling, and the United States Department of Agriculture has not identified the outbreak's original source.
How serious is the trafficking problem?
Disease-risk concerns
Local law enforcement and federal officials describe animal trafficking as a significant security and agricultural concern involving horses, cattle, dogs and other animals.
Evidence and enforcement limits
Authorities face limited visibility across hundreds of miles of rugged terrain, and the reported cases do not establish how widespread the trafficking is or prove that it caused disease transmission.
- Intercepted shipment
- Six horses were stopped near Redford, Texas, after crossing the Rio Grande illegally from Mexico.
- Confirmed U.S. cases
- U.S. authorities have confirmed 48 screwworm cases.
- Mexican equine cases
- Mexico's animal-health agency has confirmed more than 2,000 equine cases since 2024.
- Potential economic cost
- Experts estimate a widespread Texas outbreak could cost up to $1.8 billion.
- Horse value
- Smuggled horses can sell for at least $30,000 on the black market, according to a local sheriff's deputy.
- Recent interceptions
- Presidio County authorities have intercepted more than 50 smuggled horses in the past two years.
- Disease source
- The United States Department of Agriculture says investigations into how screwworm first reached the country are ongoing.