SANTA CRUZ COUNTY, Ariz. (KGUN) — Cattle shipments from Mexico are expected to resume at the Mariposa Port of Entry on November 30, ending a roughly 14-month suspension tied to the spread of New World screwworm, a parasitic fly that threatens livestock.
U.S. Agriculture Secretary Brooke Rollins announced the anticipated reopening Tuesday during a visit to Nogales, where she toured facilities used to screen cattle and produce entering the United States.
The facilities have undergone upgrades aimed at detecting and preventing the spread of the parasite, including additional inspection equipment and infrastructure.
“We’re managing the new world screw worm,” Rollins said. “Got that under control — we’re not out of the woods yet. But we are to the point where understand how to contain.”
Rollins said the upgraded facilities include additional canine inspection teams and dipping vats designed to strengthen safeguards against the pest.
“We added K9 teams, dog teams,” she said. “We added dipping vats — I mean we definitely built some new infrastructure.”
The New World screwworm is the larval stage of a fly whose larvae feed on the living tissue of warm-blooded animals, often entering through open wounds. Infestations can cause severe tissue damage and death if left untreated, making the parasite a significant threat to cattle producers and the broader livestock industry.
The pest was largely eradicated from the United States and much of Central America through decades of control efforts, including the release of sterile male flies to prevent reproduction.
Its resurgence in Central America and subsequent movement north prompted U.S. officials to restrict cattle imports from Mexico as they worked to prevent an outbreak north of the border.
U.S. Rep. Juan Ciscomani, an Arizona Republican who represents the state's 6th Congressional District, said the Mariposa reopening follows the resumption of cattle crossings at other ports.
“What we’re doing here is announcing another opening for cattle to start crossing now at this port,” Ciscomani said. “The first port was in Douglas, now several others have opened. And now this one has here.”
The suspension of cattle shipments has also affected the U.S. beef supply and contributed to pressure on prices, according to Rollins. She said the restrictions were necessary to protect domestic cattle herds from a potentially devastating outbreak.
“If we hadn’t closed those ports, and if we did have 90,000 cases of new world screw worm in Texas, we would have no cattle industry at all,” Rollins said. “And so you’re $6.50 a pound ground beef would probably be 15 to 20 a pound.”
The reopening is expected to help restore cattle movement across the border while maintaining inspections intended to prevent the parasite from spreading into the United States.
Rollins said officials anticipate making further progress against the pest over the coming year, though she acknowledged that the threat has not been eliminated.
“By end of next year, we’ll actually begin to push it back,” she said. “So we’re going to be done with this I believe, in a year to 18 months.”
The planned reopening of Mariposa is part of a broader effort to resume cross-border cattle trade while protecting U.S. livestock from another screwworm outbreak.
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Eddie Celaya is a multimedia journalist at KGUN 9. Born in Tucson and raised in the Phoenix area, Eddie is a life-long Arizonan and graduate of the University of Arizona who loves the desert and mountains and hates the cold. Previously, Eddie worked in print media at the Arizona Daily Star. Share your story ideas with Eddie at edward.celaya@kgun9.com, or by connecting on Facebook or Instagram.
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