Confirmed cases of New World screwworm in the United States have climbed to 116, with 56 still active, according to US Department of Agriculture (USDA) data reported by Texas Public Radio on 5 November. The total has nearly doubled since 21 October, when 59 cases had been counted.

The outbreak spans Texas, New Mexico and Arizona. Of the 116 confirmed animal infestations, 114 involved domestic animals, including livestock and pets. The other two were elk in West Texas, the first detections of the parasite in American wildlife in decades.

Deer season puts hunters on watch

The rise comes just as Texas’s general deer season opened on Saturday, 7 November, sending large numbers of hunters into the field. The Texas Parks and Wildlife Department estimates the state’s white-tailed deer herd at about 5.64 million, and no screwworm infestation has yet been reported in a deer.

Hunters are being asked to inspect harvested animals for suspicious wounds and to report anything unusual to state wildlife officials or a vet. The first wildlife case, a hunter-harvested elk on a game ranch in Pecos County, was confirmed on 21 October. A second elk, in Jeff Davis County, has since been confirmed. Both wildlife cases are listed as inactive.

A sharp autumn escalation

The monthly figures show how fast the outbreak has grown. USDA logged four domestic cases in August and three in September, then 36 in October and 30 in the first five days of November. New Mexico’s total has tripled to 30 cases since June, according to reporting by Searchlight New Mexico.

Recent detections include cattle in Hudspeth and Mitchell counties in Texas, a horse in Greenlee County, Arizona, and horses, cattle and a dog in New Mexico. USDA surveillance has also caught wild screwworm flies in six traps, most of them since October.

The parasite that came back after 60 years

The New World screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals. An untreated infestation can kill its host. The United States eradicated the pest from the mainland in 1966 using the sterile insect technique, in which sterilised male flies are released to crash the wild population.

The current outbreak began on 3 June 2026, when a rancher found the first case in a three-week-old calf near La Pryor in Zavala County, Texas. Since then, the USDA says it has evaluated 1,066 suspect samples nationwide, including 558 from Texas, and has ramped up production of sterile flies.

Officials stress that the response is working and that beef in shops is safe to eat. Ranchers are urged to check animals for wounds, treat them promptly and report anything suspicious to their state animal health commission or vet.