Warning: This story contains graphic images that may be upsetting to some

A mother from Memphis, Tenn., is warning others about the dangers of walking barefoot on the beaches of Florida after her son contracted a frightening and painful hookworm infection in his feet.

Kelli Mulhollen Dumas took to Facebook last week to share images of her son’s foot in which several hookworms appeared to have burrowed into his skin.

She said her son, Michael, had been visiting Pompano Beach, not far from Fort Lauderdale, when his friends decided to bury him in the sand.

Not long after, Michael and three of his companions found they had been infected with hookworm parasites, with Michael having “the worst case, by far.” She said the infection has left her son in pain and has been a “nightmare” for the family.

Mulhollen Dumas reports she contacted the local department of health that serves Pompano Beach and was told that "everyone knows to wear shoes on the beach” because of the risk of parasites.

“I assured them everyone does NOT KNOW THAT,” she wrote in the post, which has been shared more than 8,300 times.

According to the U.S. Centers for Disease Control, hookworms live in the feces of infected animals or humans, and are spread through contact with sand or soil that has been contaminated with feces.

People living in or visiting areas with warm and moist areas where sanitation is poor are most at risk for infection if they walk barefoot or allow their skin to have direct contact with contaminated sand or soil.

Last winter, a couple from Windsor, Ont., also took to Facebook to say they too had contracted hookworms while walking barefoot in the sand in the Dominican Republic. They said their feet felt itchy during the trip and then began to swell on their return home.

It wasn’t until they developed cutaneous larva migrans, the skin condition marked by a telltale red, winding rash, that doctors diagnosed them with a hookworm infection.

The infection clears up on its own after several weeks, but anti-parasitic medications can speed the process along.

In the U.S., the medications can be expensive: Mulhollen Dumas says her son is taking an antibiotic and two anti-parasitic drugs, including one that has cost her more than US$1,300, even with her insurance coverage.