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U.S. Suspends Live Animal Imports Amid Screwworm Outbreak in Mexico

Medically reviewed by Carmen Pope, BPharm. Last updated on May 15, 2025.

By I. Edwards HealthDay Reporter

THURSDAY, May 15, 2025 — The U.S. Department of Agriculture (USDA) has temporarily halted the import of live cattle, horses and bison from Mexico.

The move aims to stop the spread of New World screwworm, a dangerous flesh-eating parasite that can be deadly to animals and can sometimes harm people, CNN reported.

The screwworm was found on Mexican farms as far north as Oaxaca and Veracruz, about 700 miles from the U.S. border.

Screwworm flies lay eggs in wounds of warm-blooded animals. The larvae burrow into flesh, causing painful infections and sometimes death, according to CNN.

“The protection of our animals and safety of our nation’s food supply is a national security issue of the utmost importance,” USDA Secretary Brooke Rollins said in a statement.

The ban will last at least two weeks but could be extended and reviewed on a “month-by-month” basis, the USDA said.

“This is not about politics or punishment of Mexico, rather it is about food and animal safety," Rollins said in a statement.

Mexico’s Agriculture Secretary Julio Berdegué and President Claudia Sheinbaum both objected to the move. Sheinbaum called the move "unfair," saying, “the Mexican government has been working on all fronts from the very first moment we were alerted to the screwworm.”

This is not the first time in recent memory that the border has closed to live animal trade.

A similar shutdown happened in November when screwworms were detected in southern Mexico. The ban was lifted in February once steps were in place to inspect animals, CNN reported.

Screwworms mainly affect livestock but can also infest humans, according to the U.S. Centers for Disease Control and Prevention (CDC). Mexico confirmed its first human case in April in a 77-year-old woman, who was treated with antibiotics and is stable.

Screwworm was declared gone from the U.S. in 1966, but outbreaks have happened. In 1972, Texas reported 90,000 cases. A small outbreak occurred in 2016 in the Florida Keys, which affected some deer.

The USDA says screwworm has moved north in recent years from Central America to Mexico.

“The United States and Mexico continue efforts to interdict and eradicate NWS in Mexico and work in good faith,” the USDA said. “However, despite these efforts and the economic impact on both countries due to this action, there has been unacceptable northward advancement of NWS and additional action must be taken to slow the northern progression of this deadly parasitic fly.”

Disclaimer: Statistical data in medical articles provide general trends and do not pertain to individuals. Individual factors can vary greatly. Always seek personalized medical advice for individual healthcare decisions.

© 2025 HealthDay. All rights reserved.

Posted May 2025

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