The United States has confirmed a case of human infection with a blowfly.

On August 4, the U.S. Department of HEALTH and Human Services (HHS) confirmed the first human case of MEAT myiasis.flies in the United States. The patient, a Maryland resident, recently visited El Salvador, where the plague is still actively raging.

The BBC News agency initially reported the case, explaining that the parasite feeds on living tissue and primarily infects livestock, although it can infect humans in rare cases. This case has raised alarm in the US public health community, despite authorities describing the current public health risk as "very low."

U.S. Department of Health and Human Services spokesman Andrew Nixon explained that this is the first human case in the United States linked to travel to a country experiencing an active outbreak. According to the Centers for Disease Control and Prevention (CDC), people are susceptible to infection through open wounds and in areas where the flies that carry the disease are present, particularly in rural areas where livestock are present.

Background and regional expansion

According to the United States Department of Agriculture (USDA) and reports from media outlets such as The Washington Post and The Times, the screwworm fly, also known as Cochliomyia hominivorax, was eradicated from North America in the 1960s through control programs based on the mass release of sterile flies.

However, since 2023, it has been detected again in Central America and the Caribbean, has spread to Mexico and is threatening to return to the United States, according to BBC News reports and confirmations from the Animal and Plant Health Inspection Service (APHIS), cited by RFD-TV.

The Washington Post emphasized that human infestations are rare but can be serious if not treated promptly, as the larvae destroy living tissue. It also noted that the pest causes significant economic damage, as it can kill livestock and threaten agriculture .

In a similar vein, the U.S. Department of Agriculture (USDA) has estimated that a large-scale outbreak could threaten more than $100 billion in livestock-related economic activity.

Meanwhile, the London newspaper The Times reported that the U.S. Department of Agriculture (USDA) is already coordinating with the Food and Agriculture Organization of the United Nations (FAO) on a plan to release millions of sterile flies in key regions. The initial step will be to build a fly production facility in Texas, with another planned for Mexico, replicating the model that eradicated the pest from North America several decades ago.

A threat beyond animals

Although the screwworm primarily infects cattle , it can also infect pets, wildlife, and, in rare cases, humans. The U.S. Centers for Disease Control and Prevention (CDC) clarified that the risk of infection is higher in rural areas, among travelers, and among people with open wounds.

Blowfly larvae penetrate living tissue to feed, causing severe and painful lesions. In animals, this disease is often fatal if not treated promptly. In humans, treatment involves surgical removal of the larvae and antibiotics to prevent secondary infections.

As BBC News points out, the Maryland case is a reminder that regional health issues can easily cross borders in an interconnected world.

Context in El Salvador

The Maryland case is directly related to the situation in El Salvador, where plague was confirmed in late 2024. Since then, local authorities have maintained a state of animal health emergency to contain the spread of the disease.

According to the Salvadoran Ministry of Agriculture and Livestock, 356 cases of screwworm infestation were recorded between December 2024 and March 2025 in animals of various species, including cattle, pigs, horses, dogs and cats.

The Ministry of Health also reported three human cases of the disease, none of which were fatal. The patients received prompt treatment and were discharged without serious complications.

Plague has particularly affected domestic animals in both urban and rural areas. Veterinary clinics are reporting an increase in visits to vets for infected wounds in dogs and cats, causing concern among pet owners.

Furthermore, agricultural producers reported difficulties accessing medications and medical supplies. The Eastern Agricultural Council of Smallholders (CAMPO) reported that the initial response was limited, and smallholder farmers faced difficulties accessing recommended medications.

The Salvadoran government continues to implement inspection protocols and control campaigns, but experts warn that eradication could take several years and will require international cooperation, as has been the case in past decades.

Global consequences

The confirmation of the first human case in the United States suggests that screwworm is no longer a problem isolated to rural Central America, but is a continental threat.

As The Times newspaper explained, the key will be maintaining multinational coordination to prevent the parasite from re-emerging in North America, where it was eradicated through sustained efforts over more than 30 years.

The Washington Post noted that while the current risk to Americans is low, a large-scale outbreak could have devastating economic and health consequences. According to BBC News, this case serves as a reminder of the vulnerability of healthcare systems to neglected diseases that re-emerge due to changes in mobility and ecosystems.