U.S. Suspends Livestock Imports from Mexico Amid Screwworm Outbreak

Tone & Political Bias: Center

Why: The article presents factual developments and statements from both U.S. and Mexican authorities without favoring either side or using partisan framing.

USDA Halts Imports to Prevent Screwworm Spread

On May 11, 2025, the U.S. Department of Agriculture (USDA) announced an immediate suspension of live cattle, horse, and bison imports from Mexico. This move aims to prevent the spread of the New World screwworm, a parasitic fly that poses a serious threat to livestock health and, in rare cases, to humans. The USDA clarified that the import ban is a protective measure, not a punitive one.

What Is the New World Screwworm?

The New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae infest open wounds in warm-blooded animals. The larvae consume live tissue, which can lead to death if untreated. Though the pest primarily affects livestock, it can also harm wildlife, pets, and occasionally humans. Infestations can progress rapidly, often requiring swift veterinary or medical intervention.

U.S. Eradication History and Economic Risk

The U.S. successfully eradicated the screwworm by the early 1980s using a sterile insect technique. This involved releasing millions of sterilized flies to interrupt breeding cycles. A resurgence of the parasite could cause major economic losses. For instance, a 1976 outbreak in Texas infected more than 1.4 million cattle and cost an estimated $132 million per year.

Current Outbreak in Mexico

Mexican authorities have confirmed screwworm cases in the southern states of Oaxaca and Veracruz—about 700 miles from the U.S. border. Additionally, a human case was reported in Chiapas, where a 77-year-old woman was treated for screwworm infestation. These developments have heightened concerns among U.S. officials about a possible northward spread.

Mexico Pushes Back on Suspension

Mexican President Claudia Sheinbaum labeled the U.S. decision as "unfair," asserting that her government is actively working to contain the outbreak. She called for diplomatic dialogue and cooperation rather than trade disruption, warning that the suspension could harm rural economies on both sides of the border.

Joint Efforts to Contain the Parasite

Despite the disagreement, the U.S. and Mexico continue to collaborate on containment efforts. These include deploying sterile screwworm flies in affected areas across southern Mexico and Central America. The USDA has indicated that the ban on livestock imports will be reviewed on a monthly basis and lifted once it is safe to do so.

The screwworm outbreak has reignited concerns over cross-border biosecurity and highlighted the economic and public health vulnerabilities tied to livestock trade. Both countries remain in ongoing talks to monitor and control the spread of the pest.