Ringworm is a common fungal skin disorder otherwise known as "tinea" or dermatophytosis. It is caused by a fungus that can live on skin, surfaces like gym floors, and household items like towels, bedding, and clothes. While there are multiple forms of ringworm, the most common forms affect
- the skin on the body
- the scalp
- the feet ("athlete's foot"), or
- the groin ("jock itch").
Ringworm attacks dead tissues in places like the hair, nails, and leftover dandruff. But our bodies' immune reactions and local bacterial infections enable ringworm to turn healthy, living skin red and itchy.
Despite its name, ringworm is not caused by a worm. The ancient Greeks called ringworm "herpes," meaning "ring," while the ancient Romans called it "tinea," referring to the larval stage of a clothes moth.
Characterized by round skin lesions (rings) and early belief that the infection was caused by a parasitic worm, the English word "ringworm" was born sometime in the early 15th century. We now know a fungus causes the condition, and not a worm, but the name has stuck.
It’s a Fungus!
It wasn't until 1841 that anyone realized fungus could be responsible for ringworm. In that year, Hungarian physician David Gruby demonstrated that favus, a scalp infection, had a fungal cause. Unfortunately, his research went largely ignored.
In 1934 Chester Emmons published a careful study of several species of infectious fungi, which helped pave the way for our modern understanding of the disease.
Fungal Infections in WWII
American servicemen started contracting ringworm in the humid Pacific Theater during WWII. That's when the U.S. government launched an intensive study of fungal diseases.
Before then, scattered studies of fungus infections conducted in isolation had led researchers to give about 1,000 different names to about 350 species of related fungus. That study made great progress in clearing up much of the confusion.
Although the world is full of yeasts, molds, and fungi, only a few cause skin problems. Ringworm fungi are known as dermatophytes -- microscopic organisms that feed on the dead tissues of your skin, hair, and nails, much like a mushroom can grow on the bark of a tree. Dermatophytes cause superficial infections—so-called because they occur on the surface of the skin.
Causes: Shower Floors, Crowded Areas
Infection is more common in unsanitary and crowded places. That's because these fungi can live on both skin and surfaces like shower floors, and can be transferred by direct contact with infected clothes, sheets, and towels. Even other mammals, including cats and dogs, can transfer these fungal infections to humans.
There are several types of ringworm of the skin, and they tend to specialize. Different infectious fungi target different body parts, including
- the face,
- the scalp,
- the hands,
- the beard,
- the groin,
- the foot, and
- the nails.
On the next several slides, we'll take a look at the various forms of infection, from the top of your head to bottom of your feet.
Tinea corporis refers to ringworm on your trunk, legs, or arms. Different fungi cause this condition in different parts of the world. It's common for this infection to originate in your feet or nails, then spread to other body parts. It may spread to your
- groin, or
When fungus affects the skin of your body, it often produces the round spots of classic ringworm, which is characterized by a red ring of scaly skin that grows outward as the infection spreads. Though children are especially vulnerable, it can infect adults as well.
Acute vs. Chronic
Tinea corporis can be acute or chronic. When acute, the fungus causes itchy, red patches that suddenly appear and may fill with pus and spread rapidly. When chronic, the infection spreads by slightly inflamed rashes more slowly, and tends to appear in body folds. When the infection is widespread and chronic, it is harder to treat and more likely to reappear.
How Long Does Treatment Take?
With treatment, this disease usually goes away within four weeks. Avoid scratching, as this may lead to additional skin infections.
One of the most distinctive signs of Tinea corporis is the appearance of an itchy, red, circular rash in the shape of a ring. This rash may resemble a target or a bullseye, and it usually has raised edges. Finding one of these is a helpful way to distinguish this rash from other common skin rashes such as eczema. Eczema and other rashes may appear similar to ringworm, but they require very different treatment.
Difference From Lyme Disease
One note of caution, though—another skin disease can also cause bullseye rashes. Lyme disease is a serious condition that can cause nerve pain, facial drooping, and brain inflammation, and its characteristic rash is also in the shape of a bullseye. One way to tell the difference is the raised lines that usually accompany fungal rashes.
While fungi cause ringworm, bacteria cause Lyme disease. That's why doctors use different treatments for the two skin conditions. Because of the serious consequences of Lyme disease, anyone in doubt should seek medical attention immediately.
Tinea manuum finds its way onto human hands through either soil, animals, or human contact. This infection is fairly uncommon and frequently confused with other skin conditions. Symptoms of Tinea manuum may include
- an inflamed rash, often with raised borders,
- peeling on the palm,
- dryness on the palm,
- mild itching on the palm, and
- a blistered rash with sticky, clear fluid on the edges of the palm or fingers.
These symptoms are usually seen on only one hand. The people most likely to contract this skin infection are those who
Tinea unguium is usually caused by one of two fungi: Trichophyton rubrum or T. interdigitale. Although Tinea unguium can refer to fungal infection of the fingernails or toenails, toenails are much more likely to contract this disease. Those especially prone to nail fungus include men, older adults, diabetics, people with peripheral vascular disease, or anyone with a compromised immune system.
Some of the symptoms of tinea unguium include:
- yellow, brown, or otherwise discolored nails,
- hard nails,
- brittle nails,
- thick nails, and
- nails that have an irregular shape.
Without proper treatment, a nail infected with this fungal infection is at risk of falling off.
Facial ringworm (Tinea faciaei) is an uncommon infection, and it can arise from contact with several sources, including
- dogs, and
Some of the common features of Tinea faciei include patches that are:
- red, scaly, and round or oval,
- often healed or less scaly and red in the middle, and
- easily aggravated by sunlight.
Perhaps because it is uncommon, this infection is often misdiagnosed as psoriasis, rosacea, contact allergic dermatitis, or many other non-fungal skin conditions.
Tinea capitis is most common in children between the ages of 3 and 7, and is less often found in adults. The hair itself can be infected by various fungi, which may be spread from cattle, horses, pigs, dogs, and cats (especially kittens). One common culprit in the United States is T. tonsurans, a fungus spread from person to person that often has no symptoms.
Some of the symptoms of ringworm on scalp include:
- dry scaling similar to dandruff that is accompanied with hair loss,
- yellow crusts and matted hair,
- black dots of hair broken off at the scalp, with a scaly surface,
- swollen lymph glands on the neck
- a smooth spot where the hair has fallen off, and
- an intensely inflamed mass similar to an abscess.
In severe cases, a large, pus-filled mass called a kerion may develop.
If you have Tinea pedis, the good news is you're not alone. Athlete's foot is the most common form of ringworm in humans. The bad news? It's also one of the most difficult to treat.
The bane of locker rooms and dormitory showers, athlete's foot can be an itchy, painful problem. This infection is most often found on the feet of young adult men. Athlete's foot can appear with several different types of symptoms, including
- dry scaling on the soles of feet that is patchy and fine,
- clusters of blisters on the sides of the feet,
- round, dry patches on the top of the feet,
- dry soles that are not inflamed, and
- moist, peeling skin between toes (athlete's foot).
How Does It Spread?
Anytime you walk around barefoot in a communal shower, bathroom, changing room, or swimming pool, you risk being infected with Tinea pedis. Even if the facility hasn't been used for months, the spores of the fungus may still be active on the surface.
What Does Athlete’s Foot Look Like?
Athlete's foot is one common form of Tinea pedis. If you find the skin between your toes moist, soft and easily pulled away, athlete's foot is a likely cause. Athlete's foot can cause a painful split in the skin, and it may give off an unpleasant smell. The symptoms of athlete's foot may not be caused by a fungus at all. They can also be caused by
- bacterial infections,
- mold infections,
- skin conditions like psoriasis and eczema,
- injury, and
- a buildup of thick corns due to toes pressing into each other.
Athletes are more likely to get athlete's foot because they fall into many categories at risk for this infection, including
- wearing shoes with poor ventilation,
- sweating intensely,
- keeping feet wet for long periods, and
- walking through common areas like locker rooms and showers.
Another itchy problem is Tinea cruris, more commonly known as jock itch. Most common among adult men, jock itch causes a scaly, reddish-brown rash with raised borders to form down the inner thighs. Sometimes ring-like rashes form on the buttocks as well. This infection is unlikely to form on the penis or vulva, or around the anus.
Although jock itch is common, it is sometimes confused with other common conditions, such as
- yeast infection,
- psoriasis, and
- intertrigo, a chafing rash which results from skin rubbing against skin.
What is barber's itch? Like certain forms of ringworm of the scalp, tinea barbae infects the hair itself on a man's face. Beards and moustaches make fertile feeding grounds for the fungi responsible for barber's itch. In the days when men frequently stopped by the barber shop for a shave, this disease was once commonly spread by barbers with unsanitary practices. Today, barber's itch is most common among farmers. Two of the fungi most commonly responsible for the condition, T. verrucosum and T. mentagrophytes, are carried by cattle and horses, respectively.
Common symptoms of tinea barbae include:
- swelling and marked crusting,
- red, lumpy areas around the face,
- hairs that are easily pulled out, and
- facial hair that breaks off.
This infection can appear on the face or neck.
Ringworm is highly contagious. The fungi thrive in warm, moist areas, making locker rooms, public restrooms, showers, public pools, saunas, and similar areas especially likely places to contract the disease. There are three ways to contract an infection, which are based on the three groups of fungi that cause infections:
- Zoophilic: "Animal-loving" fungi that live on cats, dogs, horses, cows, poultry, and other mammals.
- Anthropophilic: "man-loving" fungi that are transmitted from person to person.
- Geophilic: "earth-loving" fungi that occur naturally in the soil.
Humans are most likely to be infected by the fungus Microsporum canis, which is sometimes found on cats and dogs. Sometimes the pets who carry the fungus show no symptoms themselves.
Sources of Infection
To become infected, a person must come in contact with either an infected skin or hair fragment or a fungal spore. Spores can live for years in blankets, clothing, bedding, combs and other places. To make matters worse, botanists believe these spores are airborne, meaning you don't actually have to touch a person, animal, or surface that is already infected—merely being near fungal spores may be enough to become infected.
When a person contracts ringworm, dogs and cats are the most common culprits. Cats are especially vulnerable to this infection. One study showed that when a cat has it, there is a 30 to 70 percent chance someone in the household will contract the disease, too.
Ringworm on a cat usually goes away without treatment, but it takes nine months to a year. During that time the cat's hair will continue to fall out, putting it at greater risk of wounds and infections. Plus, the cat remains contagious to anyone in the home. Symptoms in cats include:
- Broken or stubbly hair
- Crusty, scaling skin
- Changes in hair or skin color
- Inflamed skin
- Circular spots where hair has fallen out
- Excessive grooming
- Infected claws
With treatment, a cat can be cleared in as little as six weeks, though it can take much longer.
For dogs, ringworm infection usually comes from the fungal species Microsporum canis, Microsporum gypseum and Trichophyton mentagrophytes.
Unlike cats, dogs often (but not always) show symptoms. Hairless, circular lesions on the head, ears, paws, and forelimbs are the main symptoms dogs show. These lesions expand, and when they do, they become more irregular in shape and may become scabby.
Puppies, malnourished or stressed dogs, and dogs that have been in a kennel or shelter are especially prone to infection.
Treatment for Dogs
A veterinarian will determine the severity of an infection before recommending treatment. There are various treatments available, including shampoos, ointments, dips, oral treatments and simply clipping back fur.
The lesions should begin to clear up in about one to three weeks. But keep treating your dog for as long as the veterinarian recommends. Just because a lesion heals does not necessarily mean the infection has been cured.
Cats and dogs aren't the only mammals susceptible to these infections. Ringworm can be transmitted from horses, pigs, cattle, rodents, and hedgehogs. These are only some of the animals that might pick up this potentially itchy disease.
Some forms of ringworm are easier to spot than others. The telltale signs of red, raised rings can alert medical professionals to the infection, which makes for a straightforward diagnosis.
At other times, however, ringworm can be difficult to diagnose. Certain types of infection are particularly resistant to diagnosis, such as infections in the face and hands. In these cases, the fungus can cause infections that resemble many other common skin diseases.
If a dermatologist has trouble reaching a diagnosis, a small scraping of the skin is usually taken. That scraping can then be cultured in a laboratory or studied under a microscope to confirm what has caused the infection in the first place.
Fungal diseases like ringworm are more difficult to treat than bacterial infections. That's because fungus have more complicated cells which are more similar to our own. This makes it difficult to develop antifungal medications that will kill the fungus, but do no harm to humans.
As a result, long-term topical and oral treatments are necessary, and they may not be 100 percent effective. Prescription-strength anti-fungals may be more effective, but require a doctor to sign off. Take medication as prescribed. Even after the infection appears to have disappeared, it may reoccur if treatment stops early.
Ringworm can be treated topically with antifungal creams containing
- clotrimazole (Cruex, Desenex, Lotrimin),
- miconazole (Monistat-Derm),
- ketoconazole (Nizoral), and
- terbinafine (Lamisil).
In severe or resistant infections on the scalp or nails, oral medications are necessary, such as:
- itraconazole (Sporanox), and
- fluconazole (Diflucan).
Ringworm is a very common infection, and anyone can contract it. Some people are especially prone to infection, though. Anyone with a compromised immune system is both at a higher risk of being infected and will have a harder time fighting off an infection.
People who use public locker rooms, showers, swimming pools, and similar communal areas that are hot and humid are also at greater risk. Athletes risk infection because they tend to sweat, and their athletic equipment sometimes traps moisture close to the skin. Athletes who make a lot of skin-to-skin contact, such as wrestlers and MMA fighters, are particularly prone to skin infections.
People who spend a lot of time with animals—farmers, veterinarians, and dog groomers, for example—also stand greater risks.
It's not easy to prevent ringworm completely. However, by taking a few simple steps, your risk of developing an infection will be lower. The next several slides provide some helpful prevention tips.
Ringworm spores can live in clothing, sports gear, towels, sheets, and combs for years. Don't use other peoples' intimate items if you want to avoid infection.
To keep ringworm off your feet, don't walk around barefoot in locker rooms, public pools, or public showers. Instead, put on a pair of sandals or slippers to give your skin a barrier of protection.
If you play a contact sport, shower and shampoo carefully after every practice or game. The same rule applies after petting a dog or cat; to avoid transmission of the ringworm fungus from your pets, be sure to wash your hands with soap and water after playing with any mammal.
To avoid trapping moisture close to your skin, wear loose-fitting clothing made of natural fibers. Change your socks and underwear at least once a day to ward off athlete's foot and jock itch.
Fungi love humidity. One of the best ways to keep them away is to stay dry. For instance, completely dry yourself off after showers and baths.
Stay stocking-footed to prevent the spread of any foot fungus to other parts of your body. Before you slide on your underwear, make sure your socks are on tight. This may prevent a case of athlete's foot from turning into an uncomfortable case of jock itch.
If your pets have patches of missing hair, take them to the vet. That's one sign of a ringworm fungal infection. Also keep an eye out for a lesion with a scaly center that looks red and irritated around the edges. Sometimes pets will show circular patches of missing hair, and at other times they will display crusty scales. If you have a cat, keep an eye out for excessive grooming, which may be your cat's way of signaling something is irritating its skin.
IMAGES PROVIDED BY:
- Dr. Libero Ajello/CDC
- Pattie Calfy/iStockPhoto.com
- Dr. Lucille K. Georg/CDC
- CDC/ Dr. Lucille K. Georg; Dr. Libero Ajello
- Dr. Harout Tanielian / Science Source
- Dr. Lucille K. Georg/CDC
- CDC/ Dr. Lucille K. Georg
- Mike Hughey, MD/Brookside Associates
- Maddyportelli / Wikipedia
- Melissa Carlson/Second Chance Animal Aid (SCAA)
Dogchatforum.com/Ringworm in Dogs
- Nicholas Monu/iStockPhoto.com
- Marcin Balcerzak/BigStockPhoto.com
- Thomas Perkins/BigStockPhoto.com
- Borre Heitmann Holmeslet/iStockPhoto.com
- Renee Lee/iStockPhoto.com
- Vladimir Piskunov/iStockPhoto.com
- Omer Sukru Goksu/iStockPhoto.com
- Sean Locke/iStockPhoto.com
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- MedlinePlus: "Ringworm"
- University of Florida: "Ringworm Is Not a Worm"
- New York Department of Health: "Fungi as Human Pathogens"
- University of Hawaii: "Ringworm"
- Online Etymology Dictionary: "Ringworm"
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- Veterinary Medicine and Biomedical Sciences, Texas A&M University: "Animals Ringworm"
- University of California, San Diego Health Library: "Understanding Tinea Unguium"
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- Cornell University College of Veterinary Medicine: "Ringworm: A Serious but Readily Treatable Affliction"
- VCA Animal Hospitals: "Ringworm in Dogs"