Ringworm (or tinea corporis) is a common fungal infection resulting from dermatophytes, which are microscopic organisms that live on the dead outer layer of skin. The fungus that causes the ring-shaped rash remains outside of your body at all times.
There is no actual worm involved. Ringworm can affect anyone at anytime.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.
The signs of ringworm look 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 three or four.
- Lesions commonly are found on the trunk, legs, arms, neck, and face (referred to as tinea faciei).
- This type of ringworm does not involve the bearded area, scalp, groin (jock itch), hands, or feet (athlete's foot).
Ringworm is very common. In a study done in an inner-city school system, approximately 6% of school children were infected. Most ringworm infections result from human dermatophytes, which are transmitted by direct contact with other human ringworm sores. Still, you can also develop ringworm from the soil or through exposure to animals (commonly the household pet).
Although the world is full of yeasts, molds, and fungi, only a few cause skin problems. These agents are called thedermatophytes, which means "skin fungi". An infection with these fungi is sometimes known as dermatophytosis. 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.
Scientific names for the most common of the dermatophyte fungi that cause ringworm include Trichophyton rubrum, Trichophyton tonsurans, Trichophyton interdigitale, and/or Trichophyton mentagrophytes, Microsporum canis, and Epidermophyton floccosum.
What are the sources of skin fungi?
Some fungi live only on human skin, hair, or nails. Others live on animals and only sometimes are found on human skin. Still others live in the soil. It is often difficult or impossible to identify the source of a particular person's skin fungus. The fungi may spread from person to person (anthropophilic), from animal to person (zoophilic), or from the soil to a person (geophilic).
Heat and moisture help fungi grow and thrive, which makes them more commonly found in skin folds such as those in the groin or between the toes. This also accounts for their reputation as being caught from showers, locker rooms, and swimming pools. This reputation is exaggerated, though, since many people with "jock itch" or "athlete's foot" have not contracted the infection from locker rooms or athletic facilities.
Although infection may go away without treatment, some ringworm may require antifungal medications applied as cream to the lesions (topical).
- Apply topical antifungal medications to the lesion itself and 1 inch beyond its border twice daily for a minimum of two weeks, and at least one week after it goes away. Keep the infected area clean and dry. Over-the-counter medications available at the drugstore include;
- miconazole 2% (Monistat-Derm, Lotrimin AF Powder, Lotrimin AF Powder Spray, Lotrimin AF Liquid Spray, and Micatin);
- clotrimazole 1% (Lotrimin AF Cream and Mycelex);
- butenafine 1% (Lotrimin Ultra, and Mentax);
- terbinafine 1% (Lamisil AT).
- Although diaper rash, yeast infections, and ringworm are all caused by types of fungus, the medications used for those infections (nystatin) are NOT effective for ringworm.
- Ringworm is highly contagious.
- avoid touching suspicious lesions;
- maintain proper hygiene by washing your hands and body frequently and laundering the linens and clothes of an infected family member separately;
- avoid contact sports such as wrestling until you have been treating the lesions for at least 48 hours.