Ringworm is a skin infection caused by a fungus. The infection causes a rash that may have a ring-shape with a raised edge. It can be quite itchy and flaky. When the scalp is infected, there is often an area of baldness. Fungal infections of the feet are usually very itchy and cause cracking between the toes.
Ringworm (or tinea corporis) is a common fungal infection resulting from dermatophytes, which are microscopic organisms that live off the dead outer layer of skin. Ringworm can affect anyone at any time. The estimated lifetime risk of developing any superficial fungal infection is 20-30%. If you live in a warm, humid climate, have direct contact with active lesions on someone else (or a pet), or have a weakened immune system (as a consequence of medical problems such as diabetes, leukemia, or AIDS), your risk for developing ringworm is higher.
Although the world is full of yeasts, molds, and fungi, only a few cause skin problems. These agents are called the dermatophytes, which means "skin fungi." 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. The skin lesions that appear with ringworm are variable, and do not necessarily form a ring. There will be hair loss, usually in small patches at first. As time goes on the patches may disappear or appear at other locations on the skin. There might be scratching due to itchiness. If the hair loss occurs on the face or feet there is a chance it is due to digging habits or exposure to rodents.
Ringworm looks like its name. It forms a red, elevated, rapidly growing, ringlike sore on the skin. The center of the ring may be clear. The sore itself may contain scales, crust, or fluid-filled areas. Itching and pain may accompany the sore (doctors call them lesions). Each lesion is less than 5 cm across (about 2 inches) and occurs alone or in groups of 3-4. Ringworm is spread by either direct or indirect contact. People can get Ringworm by direct skin-to-skin contact with an infected person or pet. People can also get Ringworm indirectly by contact with objects or surfaces that an infected person or pet has touched, such as hats, combs, brushes, bed linens, stuffed animals, telephones, gym mats, and shower stalls. In rare cases Ringworm can be spread by contact with soil.
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 can clear the condition in two weeks or so. Examples of such preparations include those that contain clotrimazole (Cruex cream, Desenex cream, Lotromin cream, lotion, and solution, and Lotrisone cream); miconazole (Monistat-Derm cream and Lotrimin cream, powder, and spray); ketoconazole (Nizoral cream and shampoo); and terbinafine (Lamisil cream and solution). These treatments are effective for many cases of foot fungus as well. Systemic treatment: Some fungus infections do not respond well to external applications. Examples include scalp fungus and fungus of the nails. To penetrate these areas, oral medications are necessary.
For a long time, the only effective antifungal tablet was griseofulvin (Fulvicin, Grifulvin, and Gris-PEG). In recent years, newer agents have been introduced that are both safer and more effective. These include terbinafine (Lamisil), itraconazole (Sporanox), and fluconazole (Diflucan). Reputations die hard, however, and many people continue to fear that even these newer agents are "bad for the liver," when in fact they are quite safe when used properly.
Since fungi are everywhere it is almost impossible to prevent exposure. As is the case in many diseases, routine hygiene consisting of washing your hands frequently and keeping your pets haircoat clean will go very far in preventing this problem. Pets that chase rodents, especially into burrows, might be at an increased risk.