Ringworm

Ringworm causes a scaly, crusted rash that may appear as round, ring-like red patches on the skin.

The term ringworm or ringworms refers to fungal infections that are on the surface of the skin. The name is derived from the early belief that the infection was due to a worm, which it is not. Ringworm is a fungal infection of the skin. Nevertheless, the name ringworm remains. Some of these fungi produce a rash of round scaly spots on the skin, but many do not. On the other hand, many rounds, red spots, or rashes on the skin are not due to a fungal infection.

A physical examination of the affected skin, evaluation of skin scrapings under the microscope, and culture tests can help healthcare professionals make the appropriate diagnosis and distinctions from other conditions. A proper diagnosis is best for successful treatment.

The medical term for ringworm is tinea. (Tinea is the Latin name for a growing worm.) Healthcare professionals add another word to indicate the part of the body where the fungus is located. Tinea capitis, for instance, refers to scalp ringworm, tinea corporis to fungus of the body, tinea pedis to fungus of the feet, and so on.

Ringworm is the same skin condition caused by the same types of fungi. It is common to have several areas of ringworm at once in different body areas. However, it is often described by the area of the body affected:

• Tinea corporis: When fungus affects the skin of the trunk or limbs, it often produces the round spots of classic ringworm.
• Tinea cruris: Tinea of the groin ("jock itch") tends to have a reddish-brown color and extends from the folds of the groin down onto one or both thighs. Other conditions that can mimic tinea cruris include yeast infections, psoriasis, and intertrigo, a chafing rash that results from the skin rubbing against the skin.
• Tinea pedis: Commonly known as "athlete's foot," tinea pedis may cause scaling and inflammation with itching and burning irritation in the toe webs, especially the one between the fourth and fifth toes. Another common form of tinea pedis produces a thickening or scaling of the skin on the heels and soles. This pattern of rash is sometimes referred to as a "moccasin distribution." Occasionally, tinea causes blisters between the toes or on the sole. Aside from athlete's foot, tinea pedis is known as tinea of the foot or, more loosely, a fungal infection of the feet. Tinea pedis is an extremely common skin disorder. It is the most common and perhaps the most persistent of fungal (tinea) infections. It is rare before adolescence. It may occur in association with other fungal skin infections such as tinea cruris (jock itch).
• Tinea unguium: Tinea unguium can make the fingernails and, more often, the toenails yellow, thick, and crumbly. This is referred to as onychomycosis.
• Tinea faciei (faciale): Ringworm on the face, except in the area of the beard. On the face, ringworm is rarely ring-shaped. Characteristically, it causes red scaly patches with indistinct edges.
• Tinea manus: Ringworm involving the hands, particularly the palms and the spaces between the fingers. It typically causes thickening (hyperkeratosis) of these areas, often on only one hand. Tinea manus is a common companion of tinea pedis (ringworm of the feet). It is also called tinea manuum.
• Tinea barbae: Ringworm of the bearded area of the face and neck, with swelling and marked crusting, is often accompanied by itching, sometimes causing the hair to break off. In the days when men went to the barber daily for a shave, tinea barbae was called barber's itch.
• Tinea capitis: Scalp ringworm commonly affects children, mostly in late childhood or adolescence. This condition may spread in schools. Tinea capitis appears as scalp scaling associated with bald spots (in contrast to seborrhea or dandruff, for instance, which do not cause hair loss). Occasionally, an erion (a pus-filled, raised swelling) may develop in severe cases of ringworm of the scalp.

Although the world is full of yeasts, molds, and fungi, only a few cause skin diseases. These agents are called dermatophytes (which means "skin fungi"). An infection with these fungi is medically known as dermatophytosis. Skin fungi can only live on the dead layer of keratin protein on top of the skin. They rarely invade deeper into the body and cannot live on mucous membranes, such as those in the mouth or vagina.

Scientific names for the most common dermatophyte fungi that cause ringworm include Trichophyton rubrum, Trichophyton tonsurans, Trichophyton interdigitale, and/or Trichophyton mentagrophytes, Microsporum canis, and Epidermophyton floccosum.

Some fungi live only on human skin, hair, or nails. Others live on animals and only sometimes are found on human skin. Others live in the soil. It is often difficult or impossible to identify the source of a particular person's skin fungus. The fungi may spread from person to person (anthropophilic), from animal to person (zoophilic), or from the soil to a person (geophilic).

Heat and moisture help fungi grow and thrive, which makes them more commonly found in skin folds such as those in the groin area or between the toes. This also accounts for their reputation as being caught in showers, locker rooms, and swimming pools. This reputation is exaggerated, though, since many people with "jock itch" or "athlete's foot" have not contracted the infection from locker rooms or athletic facilities.

Ringworm occurs in people of all ages, but it is particularly common in children.

As described previously, it is possible to acquire ringworm from a variety of places and circumstances. The greatest risk factor is coming in contact with an affected individual. Warm, moist areas are favorable conditions for the growth of fungi, so areas such as communal showers and locker rooms are areas in which transmission is favorable. However, any contact with an infected person or a contaminated surface can cause ringworm infection.

The following factors can increase the risk of ringworm infection:

• Hot and humid climate
• Contact with an infected person, animals, objects, soil, or other surfaces
• Use of public gyms and public showers and playing contact sports
• Sharing clothing, towels, or bedding with an infected person
• Wearing tight or non-breathable clothing
• Wearing wet, damp, or sweat-drenched clothes for a long time
• Having a weak immune system, as may occur with diabetes mellitus, cancers, or prolonged treatment with corticosteroids or other immunosuppressing drugs

The signs and symptoms of ringworm may vary depending on the affected area of the body. An itchy rash is the most common feature. In general, the first stage of symptoms involves a red, scaly area of skin that may be slightly raised (plaque). This stage tends to worsen rapidly. The condition progresses to form the characteristic ring shape. Sometimes, these spots have an "active" outer border as they slowly grow and advance. Sometimes, scaling, crusting, raised areas or even blister-like lesions can appear, particularly on the active border. It is important to distinguish the ringworm of the body from other skin conditions, such as nummular eczema. This condition and others may appear similar to ringworm, but they are not due to a fungal infection and require different treatment.

Ringworm is a contagious disease and can be passed through skin-to-skin contact or by contact with contaminated items. The skin infection can also affect dogs and cats, and pets may transmit the infection to humans.

Ringworm can spread in the following ways:

• Skin-to-skin (or skin-to-fur) contact with infected human skin or animals
• Sharing towels and clothes with the infected person
• Contact with damp, contaminated surfaces at pools or athletic facilities
• Contact with contaminated objects or soil

Ringworm is treated by primary-care specialists, including internists, pediatricians (for ringworm in a child), and family medicine specialists. Because it is a skin condition, many people also seek medical advice from a dermatologist for ringworm. In rare, complicated ringworm infections, an infectious disease specialist may be consulted.

Often, the diagnosis of ringworm is obvious from its location and appearance. Otherwise, skin scrapings for microscopic examination and a culture of the affected skin can establish the diagnosis of ringworm. If the diagnosis is unclear, a potassium hydroxide (KOH) preparation of a skin scraping can be reviewed under the microscope to confirm the diagnosis of a fungus. In complicated cases, the species of fungus may need to be identified by culture (growing it in a microbiology laboratory) to determine the best treatment.

If a fungus infection is present and the skin problem is misdiagnosed, inappropriate treatment might be prescribed that could worsen the infection.

Home remedies cannot cure ringworm. To cure ringworm, it is necessary to take antifungal medications.

Ringworm can be treated topically (with external applications) or systemically (for example, with oral medications):

• Topical treatment: When fungus affects the skin of the body or the groin, many antifungal creams or lotions can clear the condition in around two weeks. Examples of such preparations include those that contain clotrimazole (Cruex cream, Desenex cream, Lotrimin cream, lotion, and solution), miconazole (Monistat-Derm cream), ketoconazole (Nizoral cream and shampoo), econazole (Spectazole), naftifine (Naftin), and terbinafine (Lamisil cream and solution). These treatments are effective for many cases of tinea except for tinea of the nails and scalp. Antifungal shampoo is not effective alone for tinea capitis but may be added to systemic treatment. Many of these antifungal creams are available as over-the-counter preparations. It is usually necessary to use topical medications for at least two weeks. More recently, the U.S. Food and Drug Administration (FDA) approved the antifungal medication luliconazole (Luzu), the first topical azole antifungal agent with a one-week once-daily treatment regimen for the management of tinea cruris and tinea corporis in adults aged 18 years or older.
• Systemic treatment: Some fungal infections do not respond well to external applications. Examples include scalp fungus and fungus of the nails. To penetrate these areas and for particularly severe or extensive diseases, oral medications can be used.

For a long time, the only effective antifungal tablet was griseofulvin (Fulvicin, Grifulvin, and Gris-PEG). Now, other agents are available that are both safer and more effective. These include terbinafine, itraconazole (Sporanox), and fluconazole (Diflucan). Oral medications may be given for a four-week to three-month course, depending on the type of infection.

Ringworm can be cured with appropriate treatment. Ringworm of the skin typically resolves after two to three weeks of treatment, while cases of ringworm of the scalp or nails may require treatment for a few months.

Complications of ringworm are rare and can include a secondary bacterial skin infection or a widespread fungal infection (extremely rare and more likely to occur in individuals with suppressed immune systems).

In rare cases, ringworm on the scalp can develop into a scalp condition known as kerion. A kerion is a red, pus-filled bump or growth on the scalp. You can have multiple kerions at once. Kerions can also cause you to have a fever.

If the kerion is large or particularly painful, your doctor may prescribe corticosteroid pills to relieve the pain and inflammation. Hair regrowth after a kerion can take 6-12 months.

Conventional wisdom holds that minimizing sweat and moisture can help prevent fungal infections. Common recommendations for ringworm prevention along these lines are for men to wear loose-fitting boxer shorts, for women to avoid pantyhose, and so forth. Whether these measures, some of which are quite difficult to implement, are worth all of the effort is open to question.

You can also take steps to prevent the spread of ringworm infections. Do not share clothing, towels, hairbrushes, combs, hair accessories, sports gear, or other personal-care items that cannot be washed or sanitized. Wearing sandals or shoes in gyms, locker rooms, and pools can help reduce your chances of contracting an athlete's foot. Be sure that your child also wears shoes in locker rooms and around pools. You should avoid touching pets that have signs of ringworm (typically bald spots). Wash hands after touching pets and be sure that a child washes his/her hands after touching pets.

If your pet has ringworm, wear gloves, and long sleeves when handling your pet, and vacuum often in areas of the home frequented by your pet. A veterinarian can treat your pet so that the infection can be eradicated.

You can kill fungal spores by disinfecting surfaces and bedding by using a solution of diluted chlorine bleach, benzalkonium chloride, or strong detergents.