First New World Screwworm Case Found in Texas

Key Takeaways

• USDA confirms first New World Screwworm detection in Texas since 1966.
• Infested calf found in La Pryor, prompting immediate 20km quarantine zone.
• Officials plan to release millions of sterile flies to halt the parasite spread.
• Ranchers fear herd shrinkage and rising beef prices due to the outbreak.

The United States has recorded its first case of a flesh-eating parasite in sixty years. The New World Screwworm was detected in a calf in La Pryor, Texas, marking the first confirmed presence of the species since 1966.

The United States Department of Agriculture (USDA) announced the discovery on Wednesday evening, confirming that the parasite, which had been advancing across Mexico for the past year, had crossed the border. The case was identified in a three-week-old calf, with larvae located in its umbilical area. This detection signifies the end of decades of successful containment efforts, as authorities had been working to delay the arrival of the pest since cases increased in Central America and Mexico.

The arrival of the screwworm poses significant risks to the livestock industry. Cattle ranchers in the region have long feared an outbreak that could shrink herds, reduce beef production, and drive prices higher for consumers. Screwworms are parasitic flies whose females lay eggs in open wounds and mucous membranes on animals. Once the eggs hatch, hundreds of larvae burrow through living flesh with sharp mouths. If left untreated, this infestation can eventually kill the host. While the parasite can infest people and pets, the risk to humans remains low, and human cases are rare. Furthermore, the fly poses no food safety issues for the broader public.

In response to the confirmation, the USDA and Texas authorities have established a 20km (12.4 miles) detection and quarantine zone around the site of the infestation. This measure is critical because the movement of infested animals is the most common way the parasites spread. By restricting movement in the affected area, officials hope to contain the initial outbreak and prevent further dissemination across the state.

The USDA has been preparing for a possible outbreak for some time, stating that these preparations helped delay the parasite's arrival by a year. To combat the infestation, plans are currently in motion to release millions of sterile screwworm flies. This biological control method relies on the fact that females only mate once in their lifetime. By releasing sterile males, any eggs laid by the wild females will be unfertilized and will not hatch, effectively breaking the reproductive cycle of the population.