Concern Grows Over New World Screwworm Cases in the U.S.
A Maryland resident has been identified as the first U.S. case of New World screwworm connected to travel to El Salvador, a country currently facing an outbreak. The Centers for Disease Control and Prevention (CDC) confirmed the case on August 4, alerting federal health officials who later shared the information via email.
Fortunately, the individual has since recovered, and Maryland health officials reported that no further cases were found in people or animals. The New World screwworm is a fly that lays its eggs in open wounds, and its larvae can cause serious harm by feeding on flesh. Although usually found in South America and the Caribbean, it has occasionally caused issues in the United States, especially in cattle.
The CDC is working alongside the U.S. Department of Agriculture to prevent this parasite from spreading further. Historically, the screwworm was a significant problem for American ranchers, especially in Florida and Texas, until it was mostly eradicated in the 1960s and 1970s. Experts say this Maryland case may not be the first for an American, but it is certainly one of the very few reported in recent times.
What Exactly Is the New World Screwworm?
This blue-green fly has a troubling history, once notorious for causing infestations in the 19th century. Its name comes from the larvae that can resemble screws as they burrow into flesh. Female flies lay their eggs in open wounds, eyes, or mouths—resulting in larvae that feed on tissue.
Risks to Humans
Despite the alarming nature of this parasite, officials emphasize that there is a very low risk for the general public. Those who travel to areas infested with the screwworm or who handle livestock while having untreated wounds are at a higher risk.
Symptoms include unexplained painful wounds or sores, often accompanied by a foul smell or the presence of maggots. For treatment, medical professionals must remove the larvae, sometimes requiring surgery.
Future Concerns
Could we see more cases among humans or animals in the U.S.? It’s certainly a possibility. For decades, scientists managed to keep the screwworm at bay by releasing sterilized male flies. However, recent lapses in this strategy, along with the movement of people and animals, have allowed the screwworm to spread into Central America and Mexico.
Researchers are exploring new methods to combat this parasite, while the government is ramping up efforts to control its spread. Experts indicate that if the screwworm returns, the Texas-Mexico border would likely be the first place affected.
In closing, while health officials are working diligently to monitor and manage this potential threat, it’s crucial for all to stay informed, especially as travel increases and borders remain open.


