Screwworm parasite found in US wildlife for first time, USDA confirms

Pest detected in elk on Texas ranch as infestation spreads north

By LineZotpaper

Published22 October 2026

Read Time2 min

The US Department of Agriculture has confirmed the first detection of New World screwworm in US wildlife, found in an elk on a game ranch in Pecos county, Texas, signaling the parasite's spread beyond livestock.

The USDA said on Wednesday that the elk was reported after being harvested by a hunter. The Texas animal health commission will modify a previously established infested zone, while the USDA and the Texas parks and wildlife department are conducting additional wildlife surveillance in the area.

"We encourage all hunters and landowners to be vigilant for signs of New World screwworm while they are out in the field this season," Texas wildlife division director Alan Cain said.

The parasite was eradicated from the US decades ago but has surged north from Central America through Mexico. Washington imposed a more than year-long ban on Mexican cattle imports to keep it out, resuming trade in August at an Arizona port as part of a phased reopening plan. The halt has tightened US cattle supplies and pushed beef prices to record highs.

Despite those efforts, the screwworm was detected in June on a calf in Texas's Zavala county, near the US-Mexico border. There have since been dozens of cases detected in the US this year, including on a horse and on a dog.

Analysis

Why This Matters

The screwworm had been eradicated from the US decades ago; its return threatens livestock and wildlife.
The pest's spread has already led to a year-long ban on Mexican cattle imports, tightening supplies and pushing beef prices to record highs.
State and federal agencies are expanding surveillance, indicating the risk may grow during hunting season.

Background

The New World screwworm is a parasitic fly whose larvae feed on living tissue, causing wounds and often death in animals. It was eradicated from the US in the mid-20th century but has recently surged north from Central America through Mexico, prompting trade restrictions. The USDA halted Mexican livestock imports last year and resumed them in August at an Arizona port under a phased plan. Detection in US wildlife suggests the pest is establishing a foothold beyond border-adjacent livestock.

Key Perspectives

USDA and Texas officials: Emphasize vigilance and are modifying the infested zone, with additional wildlife surveillance underway in conjunction with Texas parks and wildlife. Hunters and landowners: Urged by Texas wildlife division director Alan Cain to watch for signs of screwworm while in the field this season. Cattle producers and consumers: Already affected by import restrictions and record beef prices, and face continued risk if the pest spreads further.

What to Watch

Results of additional wildlife surveillance in Pecos county and surrounding areas.
Whether the modified infested zone expands or new cases appear in domestic livestock.
The progress of the phased reopening of Mexican cattle imports at US border ports.

Sources

Officials confirm flesh-eating New World screwworm parasite found in US wildlife · World news | The Guardian

Checked

12 claims in this story checked against 1 source: 12 supported.

Show each claim

SupportedUSDA confirmed the first detection of New World screwworm in US wildlife.World news | The Guardian: “The US Department of Agriculture (USDA) said on Wednesday it had ⁠confirmed the ⁠first detection of flesh-eating parasite the New World screwworm in US wildlife”
SupportedThe parasite was detected in an elk on a Texas game ranch.World news | The Guardian: “the first detection of flesh-eating parasite the New World screwworm in US wildlife in an ⁠elk in Pecos county, Texas . The elk was located on a game ⁠ranch”
SupportedThe detection signals the parasite’s spread beyond livestock.World news | The Guardian: “the first detection of flesh-eating parasite the New World screwworm in US wildlife”
SupportedThe parasite is spreading north.World news | The Guardian: “the pest has surged north from Central America through Mexico”
SupportedThe elk was reported after a hunter harvested it.World news | The Guardian: “The elk was located on a game ⁠ranch and was reported after being harvested by a hunter, the ‌USDA said ‌in a statement.”
SupportedThe Texas animal health commission will modify a previously established infested zone, and USDA and Texas Parks and Wildlife are conducting additional wildlife surveillance in the area.World news | The Guardian: “The Texas animal health ‌commission will modify a previously established infested zone, and the USDA and the Texas parks and wildlife department is conducting additional wildlife surveillance in the area”
SupportedAlan Cain said, “We encourage all hunters and landowners to be vigilant for signs of New World screwworm while they are out in the field this season,” and is identified as Texas wildlife division director.World news | The Guardian: ““We encourage all hunters and landowners to be vigilant for signs of New World screwworm while they are out in the field this season,” Texas wildlife division director Alan Cain said in a statement.”
SupportedThe parasite was eradicated from the US decades ago and has surged north from Central America through Mexico.World news | The Guardian: “Eradicated from the US decades ago, the pest has surged north from Central America through Mexico”
SupportedWashington imposed a more than year-long ban on Mexican cattle imports to keep the parasite out, then resumed trade in August at an Arizona port as part of a phased reopening plan.World news | The Guardian: “prompting Washington to impose a more than year-long ban on Mexican cattle imports. The US halted livestock imports ⁠from Mexico last year to keep out screwworm, but resumed trade in August at an Arizona port as part of a ‌phased reopening plan.”
SupportedThe halt tightened US cattle supplies and pushed beef prices to record highs.World news | The Guardian: “The halt has tightened US cattle supplies and pushed beef prices to record highs for American consumers.”
SupportedScrewworm was detected in June on a calf in Texas’s Zavala County, near the US-Mexico border.World news | The Guardian: “the screwworm was detected in June on a calf in Texas’s Zavala county, located near the US-Mexico border.”
SupportedDozens of cases have been detected in the US this year, including in a horse and a dog.World news | The Guardian: “There have since been dozens of cases detected in the US this year, including on a horse and on a dog.”