New World Screwworm Detected in Texas for First Time in Decades

The U.S. Department of Agriculture (USDA) recently confirmed the presence of the New World screwworm in a Texas calf, marking the first domestic case of this parasitic pest in nearly 60 years. The screwworm, which was successfully eradicated from the United States in 1966 using the sterile insect technique, is a fly species that lays eggs in the open wounds or body orifices of warm-blooded animals. Upon hatching, the larvae burrow into living tissue, causing severe, necrotic wounds that can be fatal if left untreated.

While the parasite was eliminated in the U.S. decades ago, it has remained endemic in parts of South America and the Caribbean, and has recently been migrating northward through Central America. Experts have long anticipated the possibility of a reintroduction, given the significant economic threat the pest poses to the livestock industry. Historically, these infestations have caused billions of dollars in losses, making the containment of this current outbreak a matter of national agricultural security.

In response to the discovery in Zavala County, the USDA and the Texas Animal Health Commission have launched an aggressive containment strategy. This includes establishing a 20-kilometer quarantine zone, implementing strict animal movement controls, and deploying sterile flies to disrupt the breeding cycle of the local population. Officials are also conducting intensive surveillance and community outreach to monitor for further infections.

Although human infections are rare, they are possible, particularly for those with open wounds in affected areas. Residents and livestock owners in the region are urged to inspect their animals for signs of infestation, such as foul-smelling or growing wounds, and to report any suspected cases to veterinary authorities immediately. The rapid, coordinated response aims to prevent the parasite from re-establishing a foothold in the U.S. agricultural landscape.