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Tinea

Dermatophytosis, Ringworm, Jock Itch, Tinea Pedis

What is Tinea?

Ringworm is a fairly common fungal infection that can affect several different areas of the body. It is caused by species of fungi called dermatophytes that live on the dead tissues of skin, hair and nails. Some species live preferentially on humans, others on animals.

When people use the term ringworm, they often are referring to the infection that causes a ring-shaped rash and bald spot on the skin (tinea corporis) or scalp (tinea capitis). However, ringworm also can affect the feet (tinea pedis) or the groin (tinea cruris) and other areas of the body.

Normally, a person's skin cells move from the lowest layer of the skin to the highest layer of the skin over the course of about a month. Once the skin cells reach the outermost layer, they die and scale off in flakes.

The fungus that causes ringworm grows in moist, warm environments. It lives on the outermost layer of the skin, hair and nails and feeds on the cells there. As it multiplies on the skin, it spreads out in a circle, leaving its distinctive ring-like pattern. Despite its name, there is no worm present under the skin in patients with this infection.

Ringworm is contagious, and people may become infected with the fungus from many different sources. Direct contact with an infected person can transmit the fungus. Direct contact with an infected animal's skin or hair also can cause a person to become infected with ringworm. Animals with ringworm often have a patch of skin where hair is missing. Animals known to transmit ringworm include:

  • Cats (especially kittens)
  • Dogs (especially puppies)
  • Horses
  • Ferrets
  • Rabbits
  • Guinea pigs
  • Cows
  • Goats
  • Pigs
Direct contact with contaminated, damp surfaces (e.g., public showers, locker room floors) and other contaminated items (e.g., combs, unwashed clothing) also can result in ringworm infection. In rare cases, a person can become infected with ringworm after coming into contact with infected soil.

People infected with ringworm are at risk for several complications. Ringworm may spread from the source of origin to other areas of the body. Ringworm is also associated with bacterial skin infections (from scratching the skin with dirty nails) and certain types of skin rashes (e.g., contact dermatitis). Symptoms of these conditions are similar to those of ringworm, except that bacterial skin infections may also include fever.

Types and differences of ringworm

Ringworm involves infection with the dermatophyte fungus. This fungus can affect various areas of the body. Some experts classify all of these infections as ringworm, while other authorities use the term to apply only to infections of certain areas, such as the skin or scalp. The location of the body affected by the fungus determines the name given to the infection, such as:

Tinea capitis

Occurs on the scalp and often leaves bald patches in the affected areas. One or more lesions may appear on the scalp, with or without inflammation. Baldness is usually reversible and may occur in patches or affect the entire scalp. The longer the infection persists, the more likely the hair loss will be permanent. Swollen, raw and pus-filled lesions (pustules) may develop. This type of ringworm may also be further classified as follows:
  • Black dot type. Begins as a small patch that slowly enlarges. There is no itching, but there is redness. Hairs break off at the scalp and particles accumulate in the follicle openings, appearing as black dots. If left untreated, scars may form.
  • Gray patch type. Begins as a small patch that spreads for a while then stops spreading and persists. Redness and scaling are present. Hairs break off just above the scalp level and have a frosted appearance.

Tinea corporis

Occurs on the top layer of skin on the arms, legs, trunk or face and appears as red, flat or slightly raised circular sores that may be intensely itchy. These may be dry and scaly or crusted and moist, and may be accompanied by tiny blisters or solid bumps (papules). As the sores become bigger, the center tends to clear, leaving seemingly normal skin surrounded by an infected edge.

Tinea cruris

Usually involves infection of the groin and is commonly known as jock itch. It may also affect the inner thighs and buttocks. The condition is more common in men than in women and is often transferred from a person's infected foot to the groin area (e.g., during dressing). The scrotum and penis are usually not affected. The borders of the rash are well-defined and scaly and may contain blisters or pustules. The rash increases in size over time.

Tinea pedis

Usually involves infection of the skin between the toes and is often called athlete's foot. In some cases, infection may occur on the foot itself. Typical symptoms include scaling of the skin between the toes, especially the fourth and fifth toe, with itchiness and possibly soreness. It often spreads over the sole and instep of the foot. It may later spread onto the sides or top of the foot and in severe, untreated cases, even over the ankle and leg. Small, fluid-filled blisters may also be present and the border between affected and unaffected skin tends to be very distinct. Athlete's foot is typically more severe in hot weather, when wearing heavy footwear or when perspiring excessively. One or both feet may be affected. Chronic forms tend to be gradually progressive whereas acute forms may be very sudden and tend to be intensely itchy or even painful.

How is it diagnosed?

Tinea signs and symptoms

Scaling patches on the skin of the groin, thighs and buttocks. Patches have well-defined edges. Occasionally small, pus-filled blisters appear.

  • Itching of involved areas.
  • Pain (if the skin becomes secondarily infected with bacteria).

To diagnose ringworm, a physician will begin by performing a physical examination and compiling a thorough medical history of the patient.

Because other skin problems (e.g., atopic dermatitis, psoriasis) may cause symptoms similar to those of ringworm, certain tests may be required to definitively diagnosis ringworm. For example, the fungus that causes ringworm may appear fluorescent when examined under an ultraviolet light called a Wood's lamp. In some cases, a sample of the patient's skin at the affected site may be scraped off (or a small piece of hair or nails clipped off) and examined under a microscope. In other cases, the sample may be sent to a laboratory, where the sample will be cultured (procedure in which conditions are controlled to allow for the reproduction and growth of potential pathogens in a tissue sample). If the fungi that causes ringworm appears in that cultured sample, a patient can be diagnosed as having a ringworm infection.

How is Tinea treated?

Some ringworm infections may get better on their own without any treatment. Patients with minor symptoms also may be able to get rid of their ringworm with simple self-care measures. These include keeping the skin clean and dry, washing sheets and nightclothes daily during the period of infection, and using over-the-counter antifungal medications. However, patients should not use these medications without first consulting a physician.

In other cases, ringworm infections may require treatment with prescription medications such as antifungal creams or oral medications. Oral drugs may have to be taken for extended periods of time for treatment to be effective. In addition, oral medications may cause side effects in some patients, including gastrointestinal upset, rash and abnormal liver function. It typically takes about one month before medications completely remove the fungi causing ringworm from the body. It may take additional time for the affected area to heal properly and for hair to grow back.

Antibiotics may be prescribed to help treat bacterial skin infections that may occur as a complication of ringworm.

Medications

Information
Brand
Generic
Label
http://www.nmihi.com/f/fluconazole.html
Diflucan
Fluconazole
Off-Label
http://www.nmihi.com/t/terbinafine.html
Lamisil
Terbinafine
On-Label
Gyne-lotrimin
Clotrimazole
Off-Label
Nizoral
Ketoconazole
On-Label

What might complicate it?

Left untreated, tinea may spread across infected areas and cause allergic dermatitis, loss of hair, or extensive cracking or eroding of the skin between toes and fingers. Secondary bacterial infections can develop in cracks in the skin or in hair follicles.

Predicted outcome

The prognosis for tinea infection is excellent. There may be cosmetic damage if the infection is not treated immediately, but many of these effects are short-lived.

Alternatives

Other viral or bacterial infections may resemble a more severe tinea infection. Non-infectious skin diseases include psoriasis and seborrheic dermatitis.

Appropriate specialists

Dermatologist and infectious disease specialist.

Notify your physician if

  • You have symptoms of jock itch that don't clear spontaneously in 5 days.

Last updated 2 July 2015