The New World screwworm, a flesh-eating pest with a devastating track record in livestock, has now been detected in Ixhuatlán de Madero, Veracruz, just 370 miles south of the U.S. border, and significantly north of previous hot spots. The July 8 report from Mexico's National Service of Agro-Alimentary Health, Safety and Quality (SENASICA) has triggered an immediate livestock trade shutdown.

This detection is the most northerly to date, surpassing cases in Oaxaca and southern Veracruz reported just two months ago that were less than 700 miles from U.S. territory. In May, those discoveries led to the initial port closure on May 11, 2025.

Rollins: "We Are Pausing Port Reopenings to Protect American Herds"

A previously announced phased reopening of five southern ports between July 7 and September 15 has now been scrapped. Secretary Rollins cited concerns over Mexico's containment measures and the rapidly advancing NWS front.

"The United States has promised to be vigilant - and after detecting this new NWS case, we are pausing the planned port reopenings to further quarantine and target this deadly pest in Mexico," said Rollins. "We must see additional progress combatting NWS in Veracruz and surrounding states in order to reopen livestock ports along the Southern border."

USDA Steps Up Action: Surveillance, Eradication, and Infrastructure

The USDA's 5-point plan, launched in June, remains in full force. Key strategies include:

• Stringent animal movement controls across Mexico

• Aggressive trapping and surveillance programs

• Continued USDA site visits throughout Mexico

• Expansion of sterile fly dispersal efforts

Rollins also confirmed the construction of a new sterile fly dispersal facility in South Texas, which would allow USDA to respond quickly if NWS reaches U.S. soil. A domestic sterile fly production facility is also in the design phase.

These actions form part of USDA's long-term goal to push NWS back to the Darien Gap, the natural barrier between Panama and Colombia, and keep it there.

Trade Disruption Hits Livestock Sector Hard

The renewed closure is a major blow to U.S. cattle feeders, bison ranchers, and equine markets, many of whom rely on Mexican imports for restocking. Input suppliers and border logistics operations also face immediate fallout.

With no confirmed timeline for port reopening, stakeholders are calling for enhanced communication and coordination between USDA, border states, and Mexican authorities to mitigate further economic damage.

What's at Stake?

The New World screwworm was eradicated from the U.S. decades ago, thanks to an ambitious USDA-led sterile fly release program. A reintroduction could devastate livestock herds, increase veterinary input costs, and trigger long-term disruptions to the food supply chain.

As Secretary Rollins emphasized, "We are committed to protecting our border at all costs."