Ringworm infection has nothing to do with worms. The ancient Greeks called the disease "herpes," meaning "circular," because of the distinctive appearance of the rash. The Romans believed the rash had something to do with the larval, worm-like, stages of a moth. Ringworm is caused by a common type of fungus, called dermatophytes.
Ringworm of the Skin
Adult human skin covers an area of about 20 square feet. Its functions include thermoregulation, insulation, and acting as a physical barrier against pathogens. The combination of skin oils and perspiration form a protective chemical barrier, called the "acid mantle." The acid mantle is slightly acidic, ranging in pH from about 4.5 to 6.0, with an average pH of 5.5, according to DermaNet NZ, which deters many of the bacteria, fungi and viruses that would otherwise invade the body. As long as the skin does not become injured and the acid mantle remains fully in place, skin effectively blocks infection. When skin is injured or cut, or when the acid mantle is disrupted, pathogens can invade skin and cause infection.
Dermatophytes are a group of fungi that cause a number of infections when they invade the skin. The infection contains the word "tinea" which refers to a ringworm infection, as well as the location on the body where the infection took hold. "Tinea corporis" refers to a ringworm infection of the body, while "tinea faciei" affects the face. "Tinea manuum" occurs on the hands. When ringworm infects the skin of the feet, it is called "tinea pedis," or, more colloquially, "athlete's foot." "Tinea cruris," or "jock itch," is a dermatophyte infection of the groin area.
As new skin cells are made, older cells are pushed toward the surface of the skin, where they eventually fall off. Discovery Kids reports that skin sheds between 30,000 and 40,000 dead skin cells every minute. Because of this relatively quick shedding process, dermatophytes have to quickly and continuously multiply in order to retain a colony in skin. When dermatophytes are shed along with skin cells, they can remain viable for more than a year, according to DermaNet NZ.
Ringworm of the Nails
Dermatophytes can also infect finger- and toenails, which have a high keratin content. When they do, they can cause the nail to deform and crumble. Untreated, the nail and nail bed can become destroyed by the fungus. Tinea unguium, which is also called dermatophyte onychomycosis, is a dermatophyte infection of the nails. The University of Adelaide in Australia, reports that tinea unguium affects about three percent of population in countries such as Australia, the United States and Great Britain.
Ringworm of the Hair
Dermatophytes also infect the scalp and beard and mustache areas. According to the American Academy of Family Physicians, the hair shaft is rich in keratin and when dermatophytes attack it, hair becomes brittle and breaks off. "Tinea barbae," or ringworm of the beard, affects men and women who have heavy, course facial hair. "Tinea capitis" refers to ringworm of the scalp. When it occurs, round patches of rash appear in the hair. Oftentimes, the patches are bald. Kerion is a severe infection on the scalp, according to Mayo Clinic. It causes pus-filled sores to develop. When the pus weeps and drains, it leaves crusty patches.
