A hunter’s elk in West Texas is the first wild animal in the US confirmed with New World screwworm, the USDA announced on October 21. New Mexico confirmed a case in a beef cow the same day and a calf the next. For people, the CDC still calls the risk to the US public “very low.”
The elk worries officials more than another cow would. Ranchers can inspect, treat and fence cattle, but deer and elk roam where nobody checks them. Wildlife can carry the pest across large areas and state lines, APHIS says.
Is screwworm in your state?
Texas and New Mexico hold the confirmed animal cases. Arizona had none as of October 20, KJZZ reported, citing the state agriculture department. Still, two new New Mexico cases sat about 10 miles from the Arizona line.
Texas has the most. The Texas Animal Health Commission lists 47 premises in 18 counties with a detection. The first, per the CDC, came on June 3.
The elk was a female shot on a Pecos County game ranch. A USDA lab in Kerrville confirmed the sample, Texas Parks and Wildlife said.
New Mexico’s count has climbed fast. Its first case was a dog in Lea County in June, the Albuquerque Journal reported. Grant County then logged a horse in September and a horse and a calf on October 16. Add the Otero cow and the Hidalgo calf from the state’s case page, and New Mexico has logged six cases since June.
Each case sets off an infested zone of at least 12.4 miles. Animals inside need an inspection, and treatment if required, before they move, New Mexico officials said.
Zones also lift. On October 23, Texas freed parts of Crockett and Pecos counties after traps there came up empty, the commission’s order says. It kept the rest under quarantine because of recent cases nearby.
Can pets or people get screwworm?
Both can, though US human cases remain rare. Female flies seek out fresh wounds, even a tick bite, and lay eggs there, the Albuquerque Journal reported. The larvae then feed on living flesh. Dogs are hosts too: Texas’s Pecos County zone began with a dog on June 30.
For people, a CDC risk assessment dated October 7 found “no known domestically acquired human cases in the United States.” It rates the risk as low even where the flies are present. The one US patient, in August 2025, caught it while traveling in El Salvador.
The CDC’s advice is simple. Keep wounds clean and covered, wear long sleeves outdoors, and use an EPA-registered repellent. If you see maggots in a wound, call a doctor. The CDC says “do not try to remove or dispose of the maggots yourself.”
People can’t pass it to each other, the CDC says; flies spread it. Nor is it a foodborne bug like Cyclospora, the parasite behind this summer’s outbreak and the research cuts around it. The food supply remains safe, according to USDA.
Will screwworm push beef prices higher?
Not in the data yet. Beef and veal prices in September ran 3.5% above a year earlier, USDA’s Economic Research Service said on October 23. They slipped 1.3% from August. ERS still expects an 8.7% rise for 2026, and its outlook doesn’t mention screwworm.
The bigger force is a record-low cattle herd. Beef prices are up 57% since 2020, the Dallas Fed noted in May. Screwworm adds pressure by cutting off Mexican cattle, which the US barred in July 2025.
The Dallas Fed put the cost of a 1972-scale outbreak today at about $2.5 billion for the Southwest. Households already feel the squeeze, as our look at power and grocery bills found.
Imports are now restarting one port at a time. Douglas, Arizona, reopened on August 24 and Santa Teresa, New Mexico, on September 24, according to APHIS. Columbus, New Mexico, follows on October 26. Nogales, Arizona, is due November 30 if conditions hold.
What do sterile flies actually do?
The US beat screwworm once by breeding it out. Workers sterilize male flies and release them by the millions. A female mates only once, so pairing with a sterile male leaves her with no offspring, USDA’s Agricultural Research Service explains.
Today the flies come from a plant in Panama. USDA disperses about 100 million a week over Mexico and Texas, APHIS says. Planes load them at Moore Air Base in Edinburg, Texas.
A production plant there aims for 100 million flies a week by late 2027, Rural Radio Network reported. APHIS expects 300 million a week by late 2028.
USDA’s long-term target is about 500 million a week. That matches what it used to wipe out the pest here decades ago. Until then supply is the limit, and every wild host that carries larvae outside the release zones stretches it further.
What to watch for, and where to report it
In livestock and pets, look for wounds that won’t heal, maggots, or a foul-smelling discharge. Texas Parks and Wildlife tells hunters to watch for animals that seem depressed, shake their heads, or keep apart. After a harvest, check the eyes, ears, nose, mouth and feet before moving the carcass.
Report a suspected case right away, and don’t move the animal.
- Texas livestock and pets: Texas Animal Health Commission, 1-800-550-8242
- Texas wildlife: Texas Parks and Wildlife, 512-389-4505
- New Mexico animals: New Mexico Livestock Board, 505-841-6161 (possible human cases: 1-833-796-8773)
- Wildlife elsewhere, especially near the border: USDA Wildlife Services, 866-487-3297
- Any other state: your state veterinarian, or the reporting page on USDA’s screwworm site
Cooler weather helps, but only so much. “Cold daytime temperatures can slow screwworm activity, but the risk is not completely eliminated,” said New Mexico Agriculture Secretary Jeff Witte. The next marker comes Monday, when the Columbus port reopens to Mexican cattle.
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