Ringworm is a relatively common fungal infection that can affect people of all ages. However, most types of ringworm are more common among children than adults. Outbreaks may occur in infant nurseries, daycare centers and schools.

Ringworm is most likely to occur when a person’s skin, scalp or nails are persistently wet (e.g., from sweating) or when minor injuries occur in these areas of the body. People living in humid environments are at increased risk of contracting ringworm.

People with compromised immune systems also are more vulnerable to ringworm infection. This includes patients with diabetes, HIV and AIDS. Having certain skin conditions may also increase the risk of contracting ringworm. This includes atopic dermatitis, also known as eczema, which appears as itchy, inflamed patches of skin.

Ringworm usually appears as a circular rash with sharply defined edges. These edges are dark red, with more normal-looking skin near the center. This ring-like appearance is characteristic of a ringworm infection.

More than one rash may appear on the skin, and these rashes can sometimes overlap. Rashes and other symptoms of ringworm may occur on several different areas of the body at the same time. Affected areas tend to be itchy. They may also be dry and scaly, or wet and crusty.

Additional symptoms associated with ringworm may vary, depending on the location of the rash on the body. For example, when ringworm affects the scalp or beard, the patient develops a sore resembling a pimple that gradually turns into a bald spot of scaly skin. Ringworm of the nails creates discolored, thick, crumbly nails. Ringworm of the skin starts as a red, scaly patch or bump that begins to resemble a ring or series of rings. Ringworm of the foot or groin often appears as red, scaly patches of skin.

Some patients infected with ringworm do not experience any symptoms at all.