Ringworm

Definition
Ringworm is a superficial fungal infection of the skin.

Causes/associated factors
Ringworm is caused by mold-like fungal organisms known as dermatophytes. These fungi like to live on dead tissue, such as the scalp, nails and outer layers of skin. There are many types of dermatophytes, and the infections they cause are generally classified by the body part affected. Tinea capitis refers to ringworm of the scalp, tinea barbae is ringworm of the beard, and tinea corporis is ringworm of the body -- usually areas that are exposed, such as the face, arms, legs and shoulders. Tinea cruris, or jock itch, is a fungal infection of the groin, tinea pedis is athlete's foot, and onychomycosis is a fungal infection of the nails.
Risk factors for ringworm include living in warm climates, working with animals, and having diabetes or a weakened immune system.


Transmission
Ringworm is infectious, but it's not considered highly contagious. The incubation period (time from exposure until symptoms appear) is about four to 10 days. It can be transmitted by combs, shared hats, barber tools, shower stalls, towels, shoes, backs of theater seats, telephones or by direct skin-to-skin contact. The infection can also be transferred by a dog, cat or, rarely, dirt. (When an animal has a fungal infection, it's not always evident. Hair loss may be present, usually around the animal's eyes, ears and nose. Household pets also require treatment.)

Signs/symptoms
Symptoms of ringworm include scaly, round, itchy patches that gradually expand as the condition worsens. As the patches enlarge, the central area may start to lighten, leaving a raised, red-ringed border on the skin around the central area.

Diagnosis
Diagnosis is based on your medical history and a physical exam. If your doctor decides to test for fungal organisms, skin scrapings may be taken from the affected area and analyzed under a microscope after applying a potassium hydroxide (KOH) solution.

Treatment
Ringworm can usually be effectively treated with topical medication. Over-the-counter topical cream, lotion or powder medications, such as terbinafine (brand name Lamisil, for example), miconazole (Micatin, for example), tolnaftate (Tinactin, for example) or clotrimazole (Lotrimin, for example) can be used on affected areas. Apply according to package directions, being sure to apply 1 inch past reddened areas. Most topical medications should be used for at least one week after symptoms have cleared to completely destroy the fungus.
The condition usually resolves within four weeks, but it may take up to several months, depending on which body parts are affected. If the infection is extensive, prescription medication may be needed. There may be areas of temporary hair loss on the scalp.

It's important to see or call your doctor if symptoms develop on the scalp. Ringworm on the scalp is usually treated with an oral prescription medication. If you have lesions on the scalp, be sure to shampoo every day.


Complications
Secondary bacterial infections may occur in severe cases where inflammation is present. Scarring may result. Ringworm of the scalp may also lead to scarring and permanent hair loss. People who have weakend immune systems are at risk for a more severe infection.

Pregnancy-specific information
Pregnancy is not a risk factor for ringworm.

Senior-specific information
Growing older is not a risk factor for this condition.

Prevention
If you have ringworm, avoid skin-to-skin contact with others. Don't share towels, combs or hats. Keep the affected areas clean and dry. Wash all clothing, towels and linens that have come in contact with affected areas.