In the cattle country outside Tapachula, near Mexico's southern border with Guatemala, rancher Julio Herrera inspects his herd for signs of the flesh-eating screwworm-a parasite whose maggots burrow into the flesh of living animals, often fatally if untreated.

Herrera says his efforts are undermined by a bigger problem: illegal livestock smuggling from Central America. "From Guatemala there is indiscriminate passage of stolen cattle, sick cattle. There is no health control," he told Reuters.

The outbreak, which began in November 2024, has already claimed its first human life-an 86-year-old woman in Campeche-and more than 30 confirmed human infections in late July. While treatable in both humans and animals, the parasite poses a serious economic and sanitary threat.

An Industry Under Siege
Mexico's meat sector is losing an estimated $25-$30 million monthly, according to the Mexican Association of Meat Producers (AMEG). The U.S., which imports roughly $1 billion in cattle from Mexico annually, has kept its border largely closed since May, driving up beef prices north of the border.

Authorities estimate at least 800,000 cattle cross illegally into Mexico each year, often stolen, unvaccinated, and fitted with counterfeit ear tags. Organized crime syndicates control much of this trade, using falsified documents to move animals into legitimate markets.

Government Response and Criticism
Local officials acknowledge the problem but say screwworm flies-capable of traveling far beyond road networks-are also spreading the outbreak. The federal government has announced a $51 million sterile fly production plant in Chiapas, co-funded by the U.S., but it will not be operational until 2026.

Meanwhile, measures like screwworm-detection dogs, producer training, and free de-worming treatments are being deployed. Chiapas Agriculture Secretary Marco Barba insists infected animals are not entering the food supply, seeking to dispel myths that have cut beef consumption.

But ranchers remain frustrated. "It's a business," says Jorge Ortiz, a local slaughterhouse worker and pig farmer. "It needs federal action to control."

Trade Tensions With the U.S.
Mexico has three months to resolve the crisis or risk higher U.S. tariffs. USDA officials are "staffing up in the hundreds" to verify Mexico's data, according to U.S. Agriculture Secretary Brooke Rollins.

Veterinarians in Chiapas, however, say resources aren't reaching rural areas. "Right now, it's a very serious situation," says Alfonso Lopez, who treats new cases daily.

For ranchers like Herrera, the urgency extends beyond livestock. "What happens with the coyotes, the stray dogs, the deer, the jaguar?" he asks. The screwworm, he warns, threatens all warm-blooded animals-and without stronger border enforcement, the fight may already be slipping away.