Health Desk

Ringworm Fungal Infections Are Common In The US And Are Becoming Increasingly Resistant To Treatment – 6 Questions Answered

The World Health Organization considers antimicrobial resistance to be one of the most serious threats for global health. Similar to the way bacteria have developed resistance to antibiotics, fungal infections throughout the world are becoming more drug-resistant and more deadly.

In early 2023, the New York State Department of Health reported two cases of severe tinea, a contagious type of ringworm infection. The Centers for Disease Control and Prevention later reported that they were caused by a species of fungus that has been spreading throughout South Asia over the past decade.

The Conversation spoke with Rodney Rohde, a medical laboratory professional and public health microbiologist, about the prevalence of ringworm and the growing threat of antifungal resistance around the world.

1. What is ringworm and how common is it?

When one hears the term ringworm, it likely conjures images of a nasty parasitic worm infection. However, a ringworm infection is a common infection of the skin caused by a fungus. Experts state that about 20%-25% of the population will experience a ringworm infection at any given time.

Fungi can be found almost anywhere – soil, plants, surfaces, on the skin and in our bodies, and even in the air. Research shows that there are up to 40 types of fungus that can cause these ringworm infections, with the most common types being from the genuses Trichophyton, Microsporum or Epidermophyton.

Medical terms for ringworm are "tinea" and "dermatophytosis." Tinea and dermatophytosis are synonyms for a contagious fungal infection of the skin. Other names for ringworm are based on its location on the body – for example, ringworm on the feet is commonly called athlete's foot, and ringworm associated with the groin area is referred to as jock itch. These are characterized by a persistent itchy rash that can appear flaky and cracked.

While anyone can be infected, ringworm is most commonly picked up in the following circumstances:

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– A weakened immune system or an autoimmune disease like lupus.

– Playing a high-contact sport, like wrestling; this ringworm is called tinea gladiatorum.

– Profuse sweating, also known as hyperhidrosis.

– The use of public showers or locker rooms.

– Handling or working with infected animals.

– Living in a subtropical or tropical region.

2. How can you recognize ringworm?

The hair, skin and nails of either fingers or toes are the likely landing spots for a ringworm infection. Signs and symptoms of an infection usually depend on which part of the body is affected, but generally may include hair loss and red, scaly, cracked skin. However, the most well-known sign that gives this infection its ironic and misplaced name – ringworm – is the hallmark ring-shaped rash.

3. How does ringworm spread?

Many fungi can be seen with the naked eye, such as common mushrooms or bread mold.

Fungi can grow in two forms: yeasts, which are single round cells, and molds, which are made up of many cells forming long, thin, hairlike threads called hyphae. Some of them can exhibit both forms of growth and thrive in decaying organic material like soil or a plant. But fungi can also grow in unexpected places, such as on wallpaper.

Fungi are relatively easily transmitted because of their ability to survive on a diversity of surfaces, including medical devices.

Fungal transmission occurs via three primary routes: by coming into close contact with another person who has a ringworm infection; by touching an infected animal, be it livestock, pets or wildlife; or by contacting an infected surface.

Some types of fungi can thrive where it's warm and humid. Ringworm occurs more frequently in tropical areas and during hot, humid summers.

4. How can you reduce the likelihood of getting it?

Some of the best ways to reduce or prevent a ringworm or other fungal infection include:

– Wash hands with soap and warm water.

– Have your pets checked regularly for ringworm.

– Wear shoes and socks that are made of lightweight, breathable materials to reduce moisture.

– Avoid walking barefoot in wet or humid areas like locker rooms or public showers.

– Clip fingernails and toenails regularly to keep them short and clean.

– Change socks and underwear at least once a day, since bacteria and fungi like most, humid environments.

– Avoid sharing clothing, towels, sheets or other personal items with others.

– For athletes involved in close contact sports like wrestling, shower immediately after practice or a match and keep all sports gear and uniform clean.

– Do not share sports gear such as helmets with other players.

5. What treatments are there?

A dermatologist can typically diagnose a ringworm infection visually, but in some cases a small skin scraping, hair or nail sample may be needed for microscopic examination.

There are several treatment options, including antifungal medications prescribed by a physician or dermatologist or over-the-counter products sold as a cream or ointment. A dermatologist may also prescribe an oral pill such as griseofulvin or terbinafine.

Popular over-the-counter products include clotrimazole, sold as Lotrimin or Mycelex, or topical miconazole. For more severe cases, a doctor might prescribe options such as itraconazole medications or tolnaftate.

Finally, in some cases a person may need to use antifungal shampoo and soap to clean themselves and sterilize bedding and clothing.

But treatments don't always work.

6. Why is antifungal resistance a growing problem?

Antimicrobial resistance, including antifungal resistance, is an ongoing global emergency. Experts estimate that drug-resistant infections caused roughly 1.3 million deaths around the world in 2019. By 2050 that figure could rise to 10 million deaths each year.

Over the past 10 years, South Asia has been experiencing an epidemic of antifungal-resistant ringworm caused by the spread of a novel species of fungus called Trichophyton indotineae, which causes skin disease in both animals and humans. Experts believe that inappropriate use of topical antifungal and corticosteroid medications is likely driving its spread.

In February 2023, a New York City dermatologist reported to public health officials two cases in which unrelated patients with severe tinea caused by Trichophyton indotineae were not improving with oral antifungal treatment. A CDC report found that those were the first cases of tinea from that species in the U.S. One of the two patients had no recent international travel history, suggesting that it could be a case of local transmission of Trichophyton indotineae in the U.S.

This article is republished from The Conversation, an independent nonprofit news site dedicated to sharing ideas from academic experts. The Conversation is trustworthy news from experts, from an independent nonprofit. Try our free newsletters.

It was written by: Rodney E. Rohde, Texas State University.

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Rodney E. Rohde has received funding from the American Society of Clinical Pathologists, American Society for Clinical Laboratory Science, U.S. Department of Labor (OSHA), and other public and private entities/foundations. Rohde is affiliated with ASCP, ASCLS, ASM, and serves on several scientific advisory boards. See https://rodneyerohde.Wp.Txstate.Edu/service/.

How Long Is Ringworm Contagious?

Ringworm is highly contagious. You may be contagious for 1-2 weeks before signs appear. The condition is then contagious until all the spores are eliminated from your skin, which could take several weeks or even months with treatment.

Ringworm (tinea corporis) is an infection of the skin caused by tiny fungus spores that reproduce in the dead outer layers of your skin. It's contagious as long as any spores are alive. This means it can spread on contact to other parts of your body, or to other people, even when you're being treated.

While ringworm may clear up on its own, there's no set timetable for this. It's best to seek treatment.

Several different species of fungus can cause tinea.

The name ringworm comes from the circular, ring-like appearance of the red, itchy spots that tinea causes on the skin of your trunk or extremities. Tinea can cause infections on other parts of the body, but then it often doesn't have the same appearance as ringworm.

Ringworm is highly contagious, and it spreads easily from person to person (and even from animal to person).

Athlete's foot (tinea pedis) and jock itch (tinea cruris) are caused by the same organism as ringworm. It's called ringworm when it appears on other parts of your body.

The feet and the crotch area provide a warm, moist environment for the microscopic fungal spores, known as dermatophytes, to live and reproduce. Their food supply is the protein, or keratin, that is found in your skin, especially the dead outer layers.

Athlete's foot is often spread in showers and locker rooms because the fungal spores can live and reproduce in puddles and wet spots, especially when the water is warm.

Once the fungus has infected your feet, you can spread it to other parts of your own body by touching.

Sharing towels, clothing, and bedding can spread it from person to person.

Ringworm and pets

You can also catch ringworm from an infected pet, though this is less common. But the species of fungi that causes ringworm in pets is different from those common among humans. These fungi may sometimes be transferred to a person in close contact with the pet, but the ringworm is not as likely to spread from that person to another.

Microsporum canis (M. Canis) is the most common form of ringworm in pets. Cats and dogs can both carry it, but cats are considered the most important hosts. It's also regularly found on horses and rabbits. Long-haired breeds such as Persian cats and Yorkshire terriers are reported to be more susceptible.

Both humans and animals can be carriers without showing symptoms of ringworm infection.

The incubation period for ringworm in humans is usually one to two weeks. Because the fungal spores are present before you see the ringworm outbreak, you can catch it from someone even before it shows up on them.

There are also some people and animals who can have ringworm but show no symptoms. They can still transfer the ringworm to you.

M. Canis, the common cause of ringworm in pets, can be seen under an ultraviolet light (black light). Under an ultraviolet light, it may appear on the fur within seven days of exposure. But it takes two to four weeks for the symptoms to show up on the animal's skin. During that time, your pet may be infectious without your seeing any symptoms.

As long as the fungal spores are present in the skin, the ringworm can be spread from person to person, or animal to person. You don't stop being contagious when you start using antifungal medication. However, once you start treatment, if you cover the lesions you can significantly decrease the risk of spreading them to others.

The condition is contagious until all the spores are eliminated from your skin. It's difficult even for a doctor to know when all of the fungal spores have been killed.

The fungal spores can also stay alive on clothing, bedding, and elsewhere as long as their food supply (dead skin cells) is present, and they have a moist and warm environment. Spores can live for as long as 12 to 20 months in the right environment.

There's no set time limit for a ringworm infection. Without treatment, it may go away on its own in a matter of months in a healthy person. Or it may not.

Ringworm on the body is usually treated with a topical ointment such as terbinafine. A four-week course is common, but the time can vary.

With treatment, a ringworm infection on a part of the body without hair (glabrous skin) is likely to clear up within two to four weeks of the start of treatment.

More serious cases, and infections in the scalp, can require oral antifungal pills. In this case, too, you're contagious until all the fungal spores are eliminated.

The standard treatment for ringworm is a topical antifungal preparation, such as terbanifine (Lamisil AT).

In more serious cases, your doctor may prescribe an oral antifungal, such as terbanafine, itraconazole (Sporanox, Orungal), or fluconazole (Diflucan, Celozole).

Maintaining good general hygiene is the best prevention against ringworm. Ringworm often spreads from your feet or groin area, so preventing athlete's foot and jock itch can be a first line of defense.

Some tips:

Always wear protective footwear in public showers, locker rooms, and pool areas.

Dry carefully after showering, especially your toes and groin area.

Wear cotton underwear.

Never share towels, clothing, or bedding.

Avoid skin contact with children and pets who may be infected.

CDC: Highly Contagious, Drug-Resistant Ringworm Reported In U.S. For First Time

Trichophyton indotineae, a highly contagious and drug-resistant fungus that can cause ringworm, has ... [+] already been spreading widely in South Asia. Pictured here is a rash from a ring worm infection, otherwise known as dermatophytosis or tinea. (Photo: Getty)

getty

There's a big difference between someone giving you a ring and someone giving you highly contagious, drug-resistant ringworm. While the former may already be quite common in the U.S., the latter had never really been reported in this country. That is until the May 12, 2023, issue of the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR) reported not just one but two cases of ringworm caused by Trichophyton indotineae. These were first ever reported cases in the U.S. Of this highly contagious and drug-resistant fungus that's been causing a not-so-fun epidemic in South Asia.

That's obviously not great news. While you may congratulate someone who gets a ring, the same typically shouldn't be said to someone who gets ringworm. That's especially true when the ringworm is drug-resistant, which makes such an infection even harder to treat. And a fungal infection that's harder to treat is certainly no treat at all.

Public health officials heard of these two cases from a New York City dermatologist on February 28, 2023, which happened to be National Inconvenience Yourself Day. One of the patients, a 28-year-old woman who had no history of recent international travel, had first noticed very itchy rashes on different parts of her body back in the Summer of 2021 and then eventually saw a dermatologist in December 2021. By that time she was in her third trimester of pregnancy and had developed large, round, scaly, very itchy rashes on her neck, abdomen, pubic region, and buttocks. After oral terbinafine treatment didn't do a whole lot, doctors started her on itraconazole, which eventually helped get rid of her rashes.

The second patient, a 47-year-old woman unrelated to the first patient, had a somewhat similar history. The main difference is that while the first patient hadn't had any recent international travel, this second patient was in Bangladesh when she first noticed a widespread, itchy rash. Other family members in Bangladesh had suffered from similar rashes as well. This second patient then returned to the U.S. Where she made the "rash" decision of going to the emergency department three times during the Autumn 2022. All the treatments that she'd received— including various topical antifungal and steroid creams such as hydrocortisone 2.5% ointment and diphenhydramine, clotrimazole cream, and terbinafine cream—did not relieve her symptoms. Eventually, she saw a dermatologist in December 2022. The dermatologist's first prescribed treatment, a four-week course of oral terbinafine, didn't help much. Finally, a four-week course of griseofulvin did lead to approximately 80% improvement in her symptoms. As of the writing of the CDC MMWR, doctors were still considering treatment with itraconazole, given that testing had eventually confirmed T. Indotineae as the culprit.

If you haven't figured it out yet, having ringworm is not fun, assuming that your idea of fun isn't having red, itchy, ring-shaped rashes on different parts of your body. The "ring" in the "ringworm" name comes from these ring-shape lesions. When ringworm affects parts of your body that have hair, you can suffer hair loss. Such body parts include your scalp and those that rhyme with the words "botch" and "benitals."

The "worm" in the "ringworm" name doesn't ting completely true, though. It's actually different types of fungus that can cause ringworm rather than some kind of worm. There are many other names for ringworm because things that suck tend to have many names. For example, dermatophytosis and tinea are two general names for ringworm. When it affects the main trunk of your body, it can be called tinea corporis. When it affects your scalp, it can be called tinea capitis. When it affects your feet, it can be called athlete's foot or tinea pedis. When it affects your crotch, it can be called tinea cruris or jock itch or my-crotch-is-really-itchy.

Pictured here is ringworm affecting the forehead. (Photo By BSIP/UIG Via Getty Images)

Universal Images Group via Getty Images

Various types of fungi can cause ringworm, with T. Indotineae being one of them. The CDC MMWR called T. Indotineae a novel dermatophyte species. In this case, novel means "new" and not a book like 50 Shades of Grey. As mentioned earlier, there's been an epidemic of T. Indotineae. The misuse and overuse of topical antifungal medications and corticosteroids have probably driven the spread of this drug-resistant not-so-fun fungus. While T. Indotineae infections had already been reported in Asia, Europe, and Canada, the U.S. Hadn't joined the fun until these two cases. Plus, since the first patient had no history of recent international travel, she may have gotten it from someone else in the U.S., which would mean that T. Indotineae has already been spreading in this country.

You can catch ringworm by direct contact with someone with ringworm. So don't share things like shirts, pants, skirts, sweater vests, hats, underwear, towels, combs, and jock straps with someone who is already infected. In fact, it's a bad idea to share jockstraps, underwear, or sweater vests whether or not the other person has ringworm. Getting your own jockstraps and underwear is a worthwhile investment, and no one should be wearing sweater vests anymore.

You can also get the infection from other animals that have ringworm. So don't share shirts, pants, skirts, sweater vests, hats, towels, combs, and jock straps with dogs, cats, cows, goats, pigs, and horses either when they are infected.

A third source of ringworm infections is the environment. You can find such fungi on various surfaces, especially when they are damp. Therefore, don't walk barefoot or slide crotch-first on the floors of locker rooms or public showers.

The CDC also recommends additional measure to take to prevent ringworm. This includes keeping your skin clean and dry, wearing shoes keep your feet well-ventilated, and keeping your fingernails and toenails short and clean. You should also wear clean clothes. The CDC recommends changing your socks and underwear at least once a day. This can help you prevent fungal infections and get you more dates.

Steroid creams can actually make ringworm even worse by weakening your skin and its defenses, ... [+] allowing the fungus to spread more widely and deeper in your skin. (Photo by: Jeffrey Greenberg/Education Images/Universal Images Group via Getty Images)

Jeffrey Greenberg/Universal Images Group via Getty Images

Speaking of dates, if you tend to cover yourself with steroid creams before dates, be careful. Rubbing steroid creams on anything that itches or is red can be very problematic if that itchy, reddish thing happens to be ringworm, regardless of whether it is drug-resistant. Steroid creams can actually make ringworm even worse. That's because steroid creams can weaken your skin and its defenses, allowing the fungus to spread more widely and deeper in your skin. It can also give ringworm a more unusual appearance, which is less red and less scaly. This co-called tinea incognito appearance can make ringworm harder to diagnose and be mistaken for other conditions such as atopic dermatitis otherwise known as eczema. So avoid the 'roids when its ringworm.

It is important to ring the alarms about the continued overuse of various steroid and antifungal creams. This includes telling doctors to stop prescribing such creams for anything that happens to be red and itchy. And since many such creams are already widely available over-the-counter, it means warning the public as well. In other words, "it rubs the lotion (or the cream) on its skin" shouldn't always be the solution when you've got some kind of skin issue.

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