The US Centers for Disease Control and Prevention issued a health alert Tuesday warning that the New World Screwworm, a parasitic fly, is moving north through Mexico and approaching the Texas border. The CDC is advising clinicians to watch for patients with wounds containing the flesh-eating maggots, which burrow into living tissue. The agency emphasizes immediate removal of every maggot to prevent death.

This threat is not new; the screwworm was eradicated from the US in the 1960s using a sterile male fly release program. The strategy worked for decades, creating a biological barrier in Central America. However, the barrier was breached in 2022, allowing the flies to spread north with unregulated cattle movements. The USDA has been leading the response to the costly livestock threat.

So far, the screwworm has not been detected in the US, and the CDC considers the risk to people low. However, the agency is raising awareness due to the potential for geographic spread. Mexico has reported over 1,190 human cases and seven deaths. The situation highlights the ongoing challenge of containing agricultural pests and the importance of coordinated cross-border surveillance.