U.S. Halts Southern Border Livestock Imports Amid Screwworm Threat

U.S. Halts Southern Border Livestock Imports Amid Screwworm Threat.

U.S. Agriculture Secretary Brooke Rollins announced the suspension of all live cattle, horse, and bison imports across the Southern border as of Sunday, citing a growing threat posed by the New World screwworm, a parasitic flesh-eating pest detected in southern Mexico over the past year.

What Is the Legal Basis for the Ban?

Under the authority of the Animal Health Protection Act and related federal regulations, the USDA has broad powers to halt imports to protect domestic animal health.

This suspension leverages those powers to prevent reintroduction of a parasite that was eradicated from the U.S. decades ago through intensive sterilization programs.

Secretary Rollins framed the decision not as punitive, but as “a matter of national food and animal security,” affirming that the agency is “acting swiftly to protect the integrity of our livestock industry.”

Understanding the New World Screwworm Threat

The New World screwworm fly (Cochliomyia hominivorax) poses a unique threat to warm-blooded animals, including livestock and in rare cases, humans.

Female flies lay eggs in open wounds, and the emerging larvae consume living tissue, often leading to mutilation or death if untreated.

While eradicated in the U.S. since the early 1980s, the parasite continues to affect regions of Latin America. Its northward spread toward the U.S. border has raised serious concerns among veterinary and agricultural officials.

Cross-Border Trade and Legal Ramifications

The import halt has major implications for international agricultural trade, livestock contracts, and biosecurity compliance:

Trade Disruption: The U.S. imports hundreds of thousands of livestock animals annually from Mexico, particularly for feedlots and slaughterhouses in Texas and other border states. The sudden halt is expected to disrupt supply chains and raise legal questions about force majeure clauses in livestock contracts.
Regulatory Oversight: Livestock exporters and importers must remain compliant with USDA and APHIS (Animal and Plant Health Inspection Service) regulations, which could tighten further in response to the ongoing parasite threat.
Binational Cooperation: Mexican Agriculture Secretary Julio Berdegué expressed hope for a quick resolution, stating: “We don’t agree with this measure, but we’re confident we’ll reach an agreement sooner rather than later.” Mexico and the U.S. have previously collaborated successfully on screwworm eradication and inspection protocols.

Legal and Policy Considerations for Stakeholders

Agricultural law practitioners should monitor:

USDA policy updates and inspection protocols for livestock trade
Insurance and liability implications for livestock losses due to suspended contracts
Cross-border commercial disputes triggered by force majeure claims
International trade agreements potentially affected by unilateral health measures

The USDA has confirmed it will review the ban monthly, and emphasized its commitment to re-opening trade once the screwworm threat is contained.

In the meantime, increased surveillance, field inspections, and containment strategies are being deployed, including the use of USDA “tick riders” – inspectors on horseback patrolling the southern border.

For legal professionals, this incident serves as a powerful reminder of the increasingly complex intersection between agricultural law, international trade policy, and biosecurity regulation.

The abrupt suspension of cross-border livestock imports highlights the extent to which disease control measures can trigger significant legal and commercial consequences across multiple jurisdictions.

As climate change accelerates the migration of pests and pathogens, and as zoonotic diseases pose greater threats to both public health and global food security, regulatory responses are likely to become more frequent, more urgent, and more legally intricate.

U.S. Halts Southern Border Livestock Imports Amid Screwworm Threat