First human case of flesh-eating screwworm parasite confirmed in US

August 25, 2025

The first human case of New World screwworm (NWS) myiasis in the US has been confirmed in a patient who returned from El Salvador, with confirmation occurring on August 4. This parasitic infestation of fly larvae primarily affects livestock and typically occurs in South America and the Caribbean, though it has now been confirmed in all Central American countries as well as the US and Mexico. Health authorities, including the CDC, have investigated the case but indicate the risk to US public health is currently "very low.

Who is affected

A patient who returned to the US from El Salvador
Livestock (primary targets of the parasite)
People with open wounds who travel to affected regions
Pets, wildlife, and occasionally birds (potential hosts)
The US cattle and livestock industry (potentially)

What action is being taken

The Centers for Disease Control and Prevention (CDC) is working with Maryland's health department to investigate the case
The USDA's Animal and Plant Health Inspection Service is partnering with other agriculture agencies, the state department, and the Food and Agriculture Organization of the United Nations to respond to the outbreak

Why it matters

This is the first human case of travel-associated NWS myiasis from an outbreak-affected country identified in the US
The parasite feeds on live tissue and can cause serious, often deadly damage to animals
A screwworm outbreak in livestock could have severe economic impacts, potentially threatening more than $100 billion in economic activity tied to the cattle and livestock industry
The pest has now spread to all Central American countries despite efforts to halt its northward movement

What's next

No explicit next steps stated in the article

Read full article from source: BBC