Ringworm

This redirect is about the fungal infection. For the band, see Ringworm (band).

Ringworm

Ringworm, also known as “Tinea,” is an infection of the skin, characterized by a reddish to brownish raised or bumpy patch of skin that may be lighter in the center, giving the appearance of a “ring.” Contrary to its name, ringworm is not caused by a worm but by parasitic fungi (Dermatophytosis). It can exist anywhere on the body.

Fungi are organisms that survive by eating plant or animal material, those that cause parasitic infection (dermatophytes) feed on keratin, the material found in the outer layer of skin, hair, and nails. These fungi thrive best on skin that is moist, hot, and hidden from the light. Together with the other dermatophytosis, up to twenty percent of the population has one of these infections at any given moment.

Transmission

Ringworm is very common, especially in children, and may be spread by skin-to-skin contact, as well as via contact with contaminated items such as hairbrushes or through the use of the same toilet seat as an infected individual. Ringworm spreads readily, as those infected are contagious even before they show symptoms of the disease. Participants in contact sports such as wrestling have a risk of contracting the fungal infection through skin-to-skin contact.

Ringworm is mildly contagious. Ringworm is also a common infection in domestic animals, especially farm animals, dogs and cats and even small pets like hamsters or guinea pigs. Humans can contract ringworm from these animals as humans are in close contact with them. Chickens may also be a source, due to the dirty conditions in which many poultry live and in which ringworm may thrive. Ringworm can also be caught from other humans, both by direct contact and by prolonged contact with flakes of shed skin (from sharing clothes or from house dust, for instance).

To catch ringworm, you have to be exposed to it and you have to be susceptible. Some people are much more susceptible than others. Those with eczema or other skin problems get ringworm more easily because the protective barrier of the skin's outer layer is less intact. Children are more susceptible before puberty. Some people are genetically predisposed, and can get it easily throughout life.Can be transfered from animals to humans

Symptoms and diagnosis

The best known sign of ringworm in people is the appearance of two or more red raised itchy patches with defined edges, not unlike the herald rash of Pityriasis rosea. These patches are often lighter in the center, taking on the appearance of a ring with hyperpigmentation around the circumference caused by an increase in melanin. If the infected area involves the scalp or beard area, then bald patches may become evident. The affected area may become itchy for periods of time.

Plucked hair treated with KOH showing ectothrix spores and hyphae from a case of feline ringworm

Doctors can diagnose ringworm on sight, or they may take a skin scraping, or in the case of animal ringworm or tinea capitis, examine plucked hairs for fungal elements. This is examined under a microscope, or put on an agar plate in a microbiology laboratory and allowed to grow.

Specialized agar plate, called Dermatophyte Test Medium is used to culture and identify ringworm organisms

Some of the fungi fluoresce under a black light examination, often with a Wood's lamp.

In domestic animals, ringworm can cause a variety of symptoms, but most cases show scaling and patches of hair loss. Some cats can be carriers, but show no symptoms.

Sometimes a ringworm infection may cause skin lesions in a part of the body that is remote from the actual infection. Such lesions are called "dermatophytids". The lesions themselves are fungus-free, and normally disappear upon treatment of the actual infection. The most common example is an eruption in the hands resulting from a fungus infection of the feet. Dermatophytids are essentially a generalized allergic reaction to the fungus.

Treatment

Topical antifungal drugs containing miconazole (Daktarin, Micatin & Monistat), clotrimazole (Canesten, Hydrozole), terbinafine (Lamisil), butenafine and tolnaftate (Tinactin), many available without a prescription, are used to clear up the infection. Pyrithione zinc, found in Head & Shoulders shampoo, is a very effective treatment for ringworm on the scalp and can be used as a body wash to assist in overall treatment.

On September 28, 2007, the U.S. Food and Drug Administration stated that Terbinafine (Lamisil by Novartis AG) is a new treatment approved for use by children aged 4 and up. Antifungal granules can be sprinkled on a child's food to treat ringworm of the scalp, Tinea capitis. Itching, burning, cracking, and scaling that accompany this condition may prevent effective treatment. Ointments may be mixed with hydrocortisone creams such as Cortaid appear to reduce inflammation, but can allow the infection to spread in an uncharacteristic manner, resulting in a lesion known as tinea incognito. Fungal infections may take a while to clear up, but most ringworm infections should see improvement in a week or two. Treatment is usually continued for two weeks after symptoms disappear to prevent future occurrence. Types affecting the nails or scalp are very difficult to treat due to fungal infection in follicle roots or under the nail itself.

Griseofulvin is a traditional drug used to treat ringworm in both animals and people. It can be very effective, but likely requires a prescription and may produce side effects. In cats and cattle, sulfurated lime rinses are often used to treat ringworm; and dilute povidone-iodine may be used as a wash in cattle. Enilconazole, as a rinse, is an effective ringworm treatment available in many countries for treating animals.

Lufenuron, the active ingredient in Program oral flea treatment, is also commonly prescribed by vets to treat ringworm infections in cats and dogs.

Prevention

Fungi thrive in warm, moist areas, such as locker rooms and swimming pools, and in skin folds. The fungi may be present without any symptoms. To prevent ringworm:

• Do not share clothing, sports equipment, towels, or sheets. If you think you have been exposed to ringworm, wash your clothes in hot water with fungus-killing (fungicidal) soap.

• Avoid walking barefoot, wear appropriate protective shoes to the beach and wear flip-flops in locker rooms.

See also

• Folliculitis
• Pityriasis rosea
• Antifungal drugs

References

• The Merck Manual, Twelfth Edition, 1972, p. 1451

External links

• Tinea photo library at Dermnet
• Pictures Of Ringworm
• Ringworm and Radiation

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