by Robin Smith

I scanned the pharmacy aisle in search of relief from an embarrassing body problem. Foot fungus.

A few days before, I’d propped my feet up on the sofa and pulled off my socks, only to reveal yellow toenails and peeling skin between my toes. The red, scaly soles of my feet resembled the crusty skin of a country cured ham.

“Ew,” my sister said. “How long have they looked like that?”

“I dunno. Maybe a month or two,” I said.

I did not want to have foot fungus. I tried new sneakers. I changed my socks. But my feet still itched.

Finally, I gave in and went to see a doctor. She took one look at my festering feet and gave me her diagnosis: Trichophyton rubrum. It’s the scientific name for the fungus that causes athlete’s foot.

You don’t have to be an athlete to get athlete’s foot. All it takes is walking barefoot in the shower, at the gym, or by the pool, and you could end up with a pesky infection that causes itchy, cracked skin or thick, discolored toenails. Some people have no symptoms at all. My doctor reassured me that most people get fungus infections at some time or other.

Mushrooms, molds and mildew are all fungi. They live in the soil, on plants, even in the air we breathe. Human skin is crawling with fungi too — not only molds like the fuzzy film you find on rotting fruit, but also yeasts, the microscopic, single-celled members of the fungus family. Take Malassezia, which can cause dandruff if it gets out of hand.

Fungal infections can occur anywhere on the body, but are most common in warm, moist places. Think sweaty gym shorts, under diapers, and the spaces between your toes. In a study of more than a thousand people, researchers found 43 species of fungi just lurking in the tiny space under their toenails.

Fungi are able to compete with bacteria to gain a foothold on our skin by feeding on keratin, a tough protein in skin, hair and nails that bacteria can’t stomach. The idea of a fungus munching away on the dead outer layers of my skin made me squirm. But most of the time we live in harmony with our skin microbes. Taking antibiotics to control bacteria can sometimes tip the balance between fungi and bacteria in the fungus’s favor, leading to fungus flare-ups like diaper rash, which is a yeast infection.

To ease the itching my doctor sent me home with a prescription for athlete’s foot cream.

Fungus cells have more in common with human cells than they do with bacteria, she explained. This means that finding drugs that kill the fungus without harming the surrounding tissue can be tricky.

But fortunately, fungi are usually wimpy germs. For people with normal, healthy immune systems, skin fungus infections are annoying but not serious.

About the Author

Robin Smith taught writing at Duke University for four years before joining the news room at the National Evolutionary Synthesis Center in Durham, North Carolina, where she writes about life in the deep sea, atop the world’s highest mountains, and everywhere in between. Robin earned a PhD in evolutionary biology in 2005, and has published academic articles in Evolution, American Naturalist, and the American Journal of Botany. She has also written for the Raleigh News and Observer, the Charlotte Observer, and the blog column of Scientific American. Robin is a member of the National Association of Science Writers, and serves on the board of the local science writing group, Science Communicators of North Carolina. When she’s not at her desk, Robin spends her time dancing, hiking, and learning the secrets of homemade sorbet. She tweets at @NESCent and (more rarely) @robinannsmith.