Flesh-eating screwworm arrives in US with first case detected in Texas cattle

June 4, 2026

The New World Screwworm, a flesh-eating parasite that hasn't been seen in the United States since 1966, has been confirmed in a young calf near the Texas-Mexico border after spreading through Central America and Mexico over the past year. The parasitic fly lays eggs in open wounds of warm-blooded animals, and the hatching larvae consume living tissue, potentially killing their hosts without treatment. Authorities are implementing containment measures including a quarantine zone and planning to release sterile flies to prevent reproduction, though some officials criticize the federal response as too slow.

Who is affected

A three-week-old calf in La Pryor, Texas (confirmed infected)
Cattle ranchers in the US (facing potential outbreak)
Livestock producers in South Texas
Consumers (potential for higher beef prices)
People and pets in affected areas (low risk)
Warm-blooded animals generally

What action is being taken

USDA and Texas authorities are establishing a 20km detection and quarantine zone
USDA personnel have arrived in South Texas to support operations
Plans are in motion to release millions of sterile screwworm flies
Efforts to delay the parasite's arrival have been under way since cases began increasing in Central America and Mexico

Why it matters

This is significant because it marks the return of a dangerous parasite to the US after nearly 60 years of absence. The outbreak threatens the cattle industry with potential herd reductions, decreased beef production, and higher consumer prices. The parasite's ability to kill host animals if left untreated, combined with its spread through animal movement, creates urgency for containment to prevent widespread agricultural and economic damage across Texas and potentially other states.

What's next

Release of millions of sterile screwworm flies (planned)
Continued vigilance requested from livestock producers
Ongoing support operations in South Texas by USDA personnel

Read full article from source: BBC