William Schaffner, MD, professor of preventive medicine and infectious diseases, Vanderbilt University Medical Center, Nashville.
Mycosis or fungal infections are caused by a fungus, such as a yeast or mold, rather than a bacterium or virus. There are millions of fungi around the world, in the air and in the soil, and we carry some ourselves in places like the gastrointestinal tract (starting in the mouth) and on the skin. They usually don’t bother us, unless something triggers their overgrowth. Fungal infections are often opportunistic: They multiply to problematic levels when the opportunity presents itself, such as when taking antibiotics for another infection changes the body’s microbiome.
Anyone can get a fungal infection, but you’re at higher risk if you have certain medical conditions, such as diabetes or a weakened immune system from illnesses such as cancer or HIV/AIDS. Fungal infections are more common in areas of the body that trap moisture or are subject to a lot of friction, like the groin. Many affect the skin or nails. For instance, dermatophytes, fungi that live off skin, hair, and nail cells, can cause ringworm. Ringworm takes many forms depending on the location of the infection—athlete’s foot and jock itch are two well-known manifestations. Many types of fungi can cause onychomycosis, a fungal infection of fingernails or toenails that often discolors, hardens, and/or cracks them. While unpleasant, these are superficial infections that can be treated with antifungal medications that come as pills, lotions, powders, mouthwash, shampoo, or eye drops, as appropriate.
There are more than a hundred yeasts under the candida fungus umbrella, and many infections that fall under the general term of candidiasis. Most of us know about—and many have had—the more common ones that stem from an overgrowth of the yeast Candida albicans, like thrush, which affects the throat, and vaginal yeast infections. Even some cases of diaper rash are from yeasts. While they can be troublesome, treatments can get them under control.
A growing concern currently surrounds the yeast Candida auris (C. auris), which was recognized for causing infections in people only a handful of years ago. These infections occur at a very low rate, but that rate has been increasing over the last three years. According to data from the Centers for Disease Control and Prevention (CDC) published in the Annals of Internal Medicine, from 2016, when C. auris was first reported in the United States, through December 2021, there was a total of 3,270 clinical cases (meaning infection is present) and 7,413 screening cases (meaning the fungus is detected but not causing infection). But 2022 alone saw 2,377 confirmed cases, up from 1,471 in 2021.
The CDC calls C. auris an urgent antimicrobial resistance threat because it can cause severe infections with high death rates and is often resistant to multiple antifungal drugs, notably echinocandins, the medication most recommended to treat these infections. While C. auris is not generally a worry for healthy people, like other fungi, it preys on those who are very sick, frail, and weak from complicated illnesses. Common symptoms of C. auris infection include sepsis, fever, and low blood pressure. Diagnosis is through a blood test—the sample is cultured in a lab to make the yeast easier to detect.
It’s of particular risk in healthcare settings, such as hospital intensive care units, where very ill people are already battling serious medical problems and are getting prolonged antibiotics (or multiple ones) for their underlying problems. These medications give C. auris the leg up it looks for. C. auris can contaminate surfaces in a hospital and can spread easily unless quickly recognized and addressed. Every hospital in this country has an infection control team that knows about C. auris, even if the institution hasn’t experienced it. At nursing homes, there’s less awareness, though it’s less of a threat unless it’s brought in by a patient who came directly from a hospital.
Be aware but not alarmed. If you or a loved one is in any type of medical facility, speak up if you don’t see staff following effective infection control practices like washing their hands before and after each patient contact. Ask if they have measures in place to detect C. auris infections early and isolate patients to prevent the spread.
Practicing good personal hygiene and protecting yourself from various fungi in your environment is key:
If you live in an area with known harmful fungi in the environment, like the fungus Coccidioides that causes the Valley Fever infection and is a problem in California and the Southwest, wear an N95 mask when outdoors when doing dusty work to avoid breathing them in; stay indoors with the windows closed during wind or dust storms, which can blow spores around.