Everything We Know About The Human Screwworm Case & What It Means For You

A screwworm may sound like a creature straight out of a Stephen King novel. Unfortunately, it's a real pest — one that has made its way back to the United States after being kicked out years ago. According to the U.S. Centers for Disease Control and Prevention (CDC), a screwworm (or New World Screwworm) is a type of fly that can literally get under your skin. After it enters your body through an open cut or sore, it lays hundreds of eggs. When the eggs hatch, they hungrily feed on the living tissues around them. It's kind of like how a tapeworm feeds, although their food sources are different. (Read how a tapeworm infection is diagnosed.)

Having tiny screwworms burrowing into your body is as painful as it sounds. That said, an infestation of screwworm larvae is treatable through the removal of the larvae by a medical professional. Additionally, human infestations are thankfully rare (albeit deadly if untreated).

On August 4, 2025, the first case of a human being infected by a screwworm was announced by the Department of Health and Human Services (DHHS), which left many people concerned about their own health. The case involved an American traveler who returned to Maryland from a trip to Central America in summer 2025. Around that time, the individual was diagnosed with an infection that turned out to be caused by screwworms. According to reports, the patient was treated and recovered.

Does this mean you could be at risk for being contaminated with screwworm eggs as well? A statement issued by a spokesman from the DHHS to CNN noted that "the risk to public health in the United States from this introduction is very low." As veterinary entomologist Sonja L. Swiger told Scientific American, "A human coming back with [larvae] is generally not going to lead to an outbreak." Plus, you can take precautions if you're headed to a screwworm-heavy destination, like not leaving wounds uncovered and sleeping indoors.

Still, it doesn't erase the panic that screwworms are causing within the American agricultural industry. Screwworms can be a serious threat to farmers across the United States, as one outbreak could lead to the loss of countless animals. That's why the Department of Agriculture announced strategies to protect against a possible screwworm infestation. The agency intends to breed sterile male screwworm flies and release them above agricultural communities and ranches. It is also putting $100 million into technically advanced solutions to keep the screwworm flies out of the nation.

This isn't the first time that screwworms have been on the American government's "most wanted" list of pests. In the 1960s, screwworms became a huge threat, and similar steps were taken to successfully eradicate them for decades.