New World screwworm confirmed in dog in New Mexico as Texas reports 3 new cases

US Department of Agriculture (USDA) officials have confirmed New World screwworm (NWS) in a dog in New Mexico, and Texas has three more detections, in a goat and two calves. So far, the United States has six detections of the parasitic fly in the past week.

 The first two detections were announced last week were in Zavala, Texas, but the three new detections show the insect has infiltrated more territory in the United States, including La Salle County, Texas (two calves), Gillespie County, Texas (goat), and now Lea County, New Mexico (dog).

Confirmed  NWS infections in animals are also now farther from the US border with Mexico, which has reported more than 27,000 cases through June 3, according to USDA data.

Caused by the larvae of Cochliomyia hominivorax, a parasitic fly, NWS is a serious threat to livestock, wildlife, pets, and, in rare cases, people. The larvae (maggots) burrow into the living tissue of any warm-blooded animals, causing severe wounds and infections, and infection can be fatal.

This situation is evolving, and we expect new information to emerge.

“This situation is evolving, and we expect new information to emerge as our investigation continues,” said Dudley Hoskins, USDA undersecretary for marketing and regulatory programs. “USDA is committed to sharing what we learn quickly, accurately, and transparently so animal owners and local communities have the information they need to stay vigilant.

“We are working closely with our partners in New Mexico, Texas, and across the region to ensure we identify, contain, and respond to any potential cases as swiftly as possible.”

USDA at odds with Texas ag commissioner  

Last night US Secretary of Agriculture Brooke Rollins voiced growing tensions between the federal NWS response and Texas Agriculture Commissioner Sid Miller. Miller has said the USDA’s response to the threat of NWS was too slow.

“That is a very unserious comment, from perhaps an unserious ag commissioner with just a few months left,” Rollins said of Miller. “It is also a very dangerous suggestion.”

While the crux of the USDA response to the recent detections has been releasing sterile flies into the affected areas, Miller has pushed the federal agency to adopt the Screwworm Adult Suppression System, or SWASS, which combines releasing sterile flies with broader use of insecticides. Miller has urged Rollins and President Donald Trump to take more direct action, as NWS threatens already fragile beef prices and a shrinking cattle supply.

Miller has been warning that Texas was increasingly at risk for NWS because of a spike in activity in Mexico. Since 2024, Mexico has documented a rise in both animal and human cases, especially in Chiapas state. Mexico has confirmed 27,449 cases of screwworm in animals since November 2024, and as many as 2,000 are currently active. As of February this year, 141 people in Mexico had been infected.

Yesterday Rollins announced the USDA has launched a $100 million “New World Screwworm Grand Challenge” to accelerate private-sector innovation. She also said that, in the past week, more than 8,000 traps have been set along the US-Mexico border, and tens of thousands of fly samples were being analyzed.