Screwworm Cases Bring Livestock Movement Restrictions to Southern New Mexico

Much of New Mexico’s southern border region is under a state-designated screwworm “infested zone” following three confirmed animal infections, requiring ranchers in affected areas to obtain Livestock Board authorization before moving cattle. The restrictions come as two border crossings prepare to resume accepting certain livestock imports from Mexico on Oct. 26.

An interactive map published by the state shows designated areas covering the southwestern bootheel and territory east of Las Cruces. The movement restrictions are intended to limit the spread of New World screwworm, a parasitic fly whose larvae consume living tissue.

The state Livestock Board announced infections in a calf and a horse in Grant County on Oct. 16. A third case, involving a cow in Otero County, was announced Wednesday, Oct. 21. State Veterinarian Samantha Holeck said officials were coordinating with state and federal partners to investigate the infections, expand surveillance and watch for further cases.

Holeck cautioned that colder weather could slow the pest’s spread without eliminating it. She and other state officials urged livestock owners to continue checking their animals for signs of infection. The fly’s reemergence, discovered last year, has alarmed the cattle industry across much of Mexico and in New Mexico, Texas and Arizona. It moved north through Mexico after remaining largely contained in Central America for decades.

Despite the recent infections, the U.S. Department of Agriculture has authorized a limited resumption of livestock imports through New Mexico. During a Tuesday visit to Columbus, Agriculture Secretary Brooke Rollins announced that the port there would begin accepting cattle on Oct. 26. The Santa Teresa crossing is scheduled to begin accepting horses the same day.

The two crossings previously handled approximately one-third of the nation’s cattle imports before screwworm concerns led to their closure in July. According to the New Mexico Border Authority, Mexican producers send about 300,000 cattle through Columbus and Santa Teresa annually.

Authority officials said the cattle import prohibition halted a $1.3 billion industry, with the Columbus port particularly affected. The planned reopening would restore cattle imports there while allowing horse imports to resume at Santa Teresa.

USDA described the reopening as a phased process. It said another crossing, at Nogales, Arizona, could reopen if conditions continued to permit safe trade and the necessary inspection arrangements and infrastructure were ready.