Tinea corporis (ringworm) is a fungal infection of the skin that is not caused by an actual worm. The fungi usually come from the Trichophyton, Microsporum and Epidermophyton families, and are caught by close contact with another infected human or animal (e.g. cat, dog). The fungi prefer areas of the body where there is heat (under clothing, in shoes), friction (from tight clothes or skin folds rubbing together) and moisture (from sweat), and more common in the tropics. It affects both sexes and all ages equally.
The fungus settles in one spot on the skin, where a red dot may be seen. This slowly enlarges as the fungus spreads, and after a few days the centre of the red patch becomes pale again and similar to normal skin, because the infection is no longer active at this point. The infection continues to spread and forms an enlarging red ring on the skin. Multiple ring-shaped spots with a pale centre are seen on the chest, abdomen and back. It usually does not cause an itch or discomfort.
The diagnosis is proved by taking a skin scraping and examining it under a microscope for fungal spores. Antifungal creams, ointments, lotions and tinctures are usually effective. Antifungal tablets are available for more serious infections, but sometimes they are very slow to work, and may need to be taken for up to six months. Without treatment, the ringworm may persist for many months.
The prognosis is very good with proper treatment, but the infection tends to recur if treatment ceased prematurely. Children may return to school a day after appropriate treatment has been commenced.