healthHealth and Medicine

Man's Moving Rash Was Actually Worm Larvae Wriggling Under His Skin


Rachael Funnell

Social Editor and Staff Writer

clockMay 2 2022, 17:25 UTC
Strongyloides stercoralis

Strongyloides stercoralis, who longs to reach adulthood in your intestine. Image credit: Keeb thoj /

A roundworm infection caused a man to develop a curious rash that migrated across his body. Having started near his anus, the mysterious red lesions began moving quite rapidly, leading doctors to a diagnosis of a Strongyloides Hyperinfection Syndrome.

The parasite Strongyloides stercoralis was to blame for the patient’s symptoms, which are detailed in a case report published The New England Journal of Medicine. The affected patient was a 64-year-old man living in Spain who had a diagnosis of metastatic lung adenocarcinoma, a type of cancer.


While in hospital for a malignant mass that was compressing his spine, he was put on a course of high-dose glucocorticoids. A type of steroid, it’s sometimes used in cancer care to complement treatments and deal with some of the side effects.

However, within a few days, a rash appeared near the man’s anus and began to spread across his body. Doctors were able to track the lesions’ progress by drawing around them with a pen – when they looked again 24 hours later the red, wiggly marks were no longer within the ink outline (which you can see here).

The spread was rapid and affected his trunk and limbs, but following a stool examination, the identity of the traveling lines became apparent. The man was infected with roundworms and had developed Strongyloides Hyperinfection Syndrome.


The “rash” was actually larva currens. which is the body’s response to larvae migrating in the skin during an earlier stage of their life cycle. Fortunately, doctors treated the infection with a dose of the Nobel-prize-winning antiparasitic wonder drug Ivermectin (which no, does not treat COVID-19).

It’s possible the patient picked up the parasites as a result of his job as a sewage management worker, where Strongyloides stercoralis could likely be found in wastewater contaminated with human fecal matter. In fact, avoiding sewage is the Center for Disease Control and Prevention’s (CDC) second top tip for avoiding such an infection.

Strongyloides stercoralis is a rhabditid nematode that most people know as roundworms. They commonly parasitize humans and dogs by penetrating their skin as larvae (some brave scientists volunteer to be parasitized in this way for research purposes). Once in the body, they migrate to the small intestine where they become adults and reproduce to give rise to the next generation of skin-penetrating parasites.


It’s the circle of life, and it moves (through) us all.

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