USDA Confirms Dozens of New World Screwworm Cases in Texas and New Mexico Livestock

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) has confirmed multiple detections of New World screwworm (NWS), a parasitic fly whose larvae infest living tissue of warm-blooded animals, in the United States. As of mid-July 2026, trackers based on APHIS data report 35 confirmed animal cases across 14 counties in two states—34 in Texas and one in New Mexico—with 25 classified as active. GenomicEpi NWS Tracker APHIS Confirmed Detections

The first case was confirmed on June 3, 2026, in a three-week-old calf in Zavala County, Texas, marking the first continental U.S. animal detection since eradication in the 1960s (aside from a localized Florida Keys outbreak in wildlife in 2016-2017). Subsequent cases have involved cattle, sheep, goats, and dogs, with concentrations in counties such as Crockett, Edwards, Terrell, and Zavala. No wildlife or feral cases or positive wild fly traps have been reported. USDA APHIS Announcement Houston Public Media

NWS (Cochliomyia hominivorax) females lay eggs in open wounds or body openings; larvae then burrow into and feed on living flesh, potentially causing severe tissue damage, secondary infections, and death if untreated. It primarily threatens livestock, pets, and wildlife rather than humans. The Centers for Disease Control and Prevention states the risk to the U.S. public remains very low, with no reports of locally acquired human cases; earlier isolated travel-associated human cases from Central America were noted in 2025. The food supply is unaffected, as inspections prevent infested animals from entering commerce. CDC Situation Summary APHIS Screwworm.gov

The pest had been eradicated from the United States and much of North America using the sterile insect technique (SIT), which involves mass-rearing and releasing sterilized male flies that mate with wild females to produce no offspring. A barrier was maintained in Panama, but northward spread through Central America into Mexico began around 2023 due to factors including cattle movements and agricultural expansion. Detections in southern Mexico prompted USDA import restrictions and intensified SIT releases. USDA APHIS Announcement

In response to U.S. cases, APHIS and Texas Animal Health Commission have established infested zones with quarantines and movement controls, increased trapping and surveillance, treated affected animals, and ramped up sterile fly releases—both aerial (millions weekly) and ground-based—across affected and border areas. USDA is investing in expanded sterile fly production capacity, aiming toward hundreds of millions per week, and coordinating with state, federal, and industry partners under a One Health approach. Southern ports have faced livestock trade restrictions. APHIS Current Status Texas Animal Health Commission

Producers are urged to inspect livestock and pets for enlarging or draining wounds, visible larvae, or discomfort, and report suspects immediately to state animal health officials or APHIS. Early treatment is effective. While currently contained to domestic animals in limited areas, unchecked spread could impose significant costs on the livestock industry through animal losses, treatment expenses, trade impacts, and wildlife effects. Officials emphasize preparedness and rapid response tools proven in past eradications. Houston Public Media CDC Situation Summary

Why this is uncovered

Despite official dashboards, state notices, and agricultural media tracking, the detections have received limited mainstream national coverage relative to their potential agricultural and economic stakes. The story is technical, regionally concentrated in rural Texas livestock areas, lacks immediate human health drama (very low public risk, no local human cases), and competes with broader news cycles, leaving primary agency data and specialized outlets as the main sources of ongoing updates.