Border Checkpoint Stops Another New World Screwworm Case as U.S. Fast-Tracks Cattle Treatment

Mexico’s tougher, two-step treatment and added checkpoints are catching cases before they can spread—good news for producers near the border.

MEXICO CITY (RFD-TV) — A new livestock checkpoint in Montemorelos, Nuevo León, stopped a calf carrying New World screwworm—and the larvae were already dead.

Under Mexico’s reinforced rules, all animals receive a double treatment (ivermectin plus a larvicidal bath). Inspectors treated and checked the full load of 85 head and found no other cases.

This most recent case was discovered 170 miles south of the border, in a shipment of more than 80 animals. Mexico’s ag ministry says this was the second confirmation in two weeks.

The infected animal was a calf, but no other livestock was infected with screwworm. Mexican officials say that when the pest was discovered, it was already dead, primarily due to mandatory treatments in Mexico.

A detection was reported last month, located closer to the US, just 70 miles south of the Texas border. Officials said this incident is separate from the Sept. 20 detection in Sabinas Hidalgo, which was officially declared inactive on Oct. 5 after tracing, wound care for thousands of animals, trapping, and sterile-fly releases.

Farm-Level Takeaway: Border controls and mandatory treatments in Mexico, plus a new U.S. tool (Dectomax-CA1), are tightening the net on screwworm. Mexico’s tougher, two-step treatment and added checkpoints are catching cases before they can spread—good news for producers near the border.

On the U.S. side, regulators have conditionally approved Dectomax-CA1 (doramectin injection) for the prevention and treatment of screwworm in cattle, with 21 days of reinfestation protection. The move is meant to get producers a tool now while full-effectiveness data are finalized. Label restrictions and withdrawal times still apply, and veterinarians are urging the targeted use of these products as part of an integrated parasite control plan to help prevent animals from developing resistance to treatments.

Agriculture Secretary Brooke Rollins says she has been in touch with Mexican officials. As a result of this latest detection, the USDA will send crews to the region to deploy traps and release more sterile flies. Rollins says the USDA’s number one goal remains keeping the U.S. herd safe and secure.

Related Stories
NCBA CEO Colin Woodall says more conversations need to occur with stakeholders present surrounding President Trump’s proposal to lower consumer beef prices with Argentinian imports.
Corn and wheat inspections outpaced last year, but soybean movement remains seasonally active yet behind, keeping basis and freight dynamics in focus by corridor.
Bubba and Amy Miller run Miller Cattle Company in Eros, Louisiana. After visiting other homesteading fairs, they decided to put on their own.
Lawmakers are pressing for answers on how Washington’s “managed trade” approach — keeping leverage through long-term tariffs — will affect farmers, global markets, and future export opportunities.
Beef industry groups seem to agree — market-based pricing, not federal intervention, best supports rancher livelihoods and long-term beef supply stability.
Cattle groups say additional imports would offer little relief for consumers but could erode rancher confidence as the industry begins to rebuild herds.
Bioethanol is becoming a global standard. For growers, that boom comes as drops in Mississippi River levels and in soybean demand occur in tandem, leaving barge space for corn and wheat.
The government shutdown has touched nearly every sector of the ag industry since it began, and now impacts are spilling over into dairy.
Expect firm calf and fed-cattle prices — pair selective heifer retention with prudent hedging and liquidity to bridge rebuilding costs.