Yes, a potentially deadly parasite that enters people through bare feet is in the US

The Guardian recently published a story with the headline, “A deadly parasite that burrows into the body through bare feet could be multiplying in this US community.” The story was aggregated by several U.S. publishers, including iHeartRadio.

Viewers, including Jane L., reached out to VERIFY asking if the parasite really exists and is in the United States.

THE QUESTION

Is a potentially deadly parasite that enters people through bare feet in the U.S.?

THE SOURCES

• Dr. Rojelio Mejia, infectious disease physician-scientist at Baylor College of Medicine
• Dr. Julie Jacobson, president of the American Society of Tropical Medicine and Hygiene
• Study on the prevalence of intestinal parasites in a low-income Texas community
• U.S. National Library of Medicine
• Centers for Disease Control and Prevention (CDC)
• National Center for Biotechnology Information

THE ANSWER

Yes, a parasite that enters people through bare feet, called Strongyloides, is in the U.S. Most people infected with the parasite don’t experience any symptoms, but infection can be deadly for others, primarily people with suppressed immune systems.

WHAT WE FOUND

Strongyloides stercoralis is a soil-transmitted worm parasite, according to the Centers for Disease Control and Prevention (CDC).

Dr. Rojelio Mejia, an infectious disease physician-scientist at Baylor College of Medicine, says the parasite is found throughout the world, primarily in countries with tropical climates that have poor sanitation systems. In the U.S., Mejia says the parasite has been found in the Appalachian Mountains, as well as in Alabama, and as one study he authored shows, in Texas.

Strongyloides larvae, which are microscopic, often penetrate the feet of humans who walk on soil contaminated with sewage or fecal matter. It then moves through different parts of the body.

“It enters the blood system, travels up to the lungs,” Mejia explained. “In the lungs, it'll go through a couple of changes and it'll crawl its way up your trachea, and you swallow it into your esophagus down into your stomach. And then when it reaches the small intestine and the intestinal system, then it starts replicating itself or giving birth.”

After reproduction, most of the larvae are excreted through feces, the CDC says. The larvae can make their way to the soil through sewage, which is why the parasite is often found in impoverished areas. From there, the larvae can enter the skin of another human and the cycle perpetuates.

But not all the larvae leave the body. Dr. Julie Jacobson, a family practice physician who is also president of the American Society of Tropical Medicine and Hygiene, says a unique quality of the Strongyloides is that it can reinfect humans once it’s inside the body.

“So, people can become more heavily infected,” Jacobson said. “You can be infected and then keep that infection for a very long period of time because it exists and can continue its life cycle while in the human body, and reproduce, both contaminating the environment but also living within the human host and extending many life cycles within the human host.”

According to the U.S. National Library of Medicine, most people don’t have symptoms when they are infected by Strongyloides, a disease known as strongyloidiasis. People who do exhibit symptoms typically experience discomforts such as abdominal pain, a cough, diarrhea or a rash.

But the disease can be fatal — particularly for those with suppressed immune systems.

“At its worst is when people get treated with a steroid or become immunosuppressed for some reason, and then the parasite gets out of control and then can just really take over the body and cause people to get extremely ill and even die,” Jacobson said.

People with symptoms of strongyloidiasis are advised to contact their doctor. A blood test is often used to determine whether a person is infected, the CDC says. Mejia noted that in many of the countries where the parasite is most prevalent, there is limited access to doctors, so many people across the world don’t know they’re infected.

Mejia and Jacobson said people diagnosed with strongyloidiasis are typically treated with anti-parasite medicines like ivermectin – the drug that some people have taken in an effort to treat COVID-19 despite U.S. health agencies warning against it.

“There’s been less supplies for people who really need it for strongyloidiasis,” Mejia said.

An article published on the National Center for Biotechnology Information’s website describes strongyloidiasis as “one of the most neglected of the so-called neglected tropical diseases.” 

“These are solvable problems,” said Jacobson. “So, we don’t need to be afraid of them. We just need to tackle them. And that is by increasing awareness and making sure that tests are available, and that treatment is available, and that we deal with the underlying pieces that may be causing that environmental exposure, where there may be poor septic systems and poverty.”

At an individual level, the CDC says people can reduce their risk of infection by wearing shoes when walking on soil and avoiding contact with sewage and fecal matter.

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