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Dermatophytes (Ringworm)

Dermatophytes are types of fungi that cause common skin, hair and nail infections. Infections caused by these fungi are also known by the names “tinea” and “ringworm.” It is important to emphasize that “ringworm” is not caused by a worm, but rather by a type of fungus called a “dermatophyte.” One example of a very common dermatophyte infection is athlete’s foot, which is also called tinea pedis. Another common dermatophyte infection affecting the groin area is jock itch, also known as tinea cruris.

Trichophyton rubrum and Trichophyton tonsurans are two common dermatophytes. These two species are usually transmitted from person to person. Another common dermatophyte is Microsporum canis, which is transmitted from animals such as cats and dogs to people. Dermatophytes like to live on moist areas of the skin, such as places where there are skin folds. They can also contaminate items in the environment, such as clothing, towels and bedding.


Dermatophyte infections can affect the skin on almost any area of the body, such as the scalp, legs, arms, feet, groin and nails. These infections are usually itchy. Redness, scaling, or fissuring of the skin, or a ring with irregular borders and a cleared central area may occur. If the infection involves the scalp, an area of hair loss may result. More aggressive infections may lead to an abscess or cellulitis. Areas infected by dermatophytes may become secondarily infected by bacteria.

Symptoms typically appear between 4 and 14 days following exposure.


Your doctor may make a presumptive diagnosis based on your symptoms and physical examination. To confirm the diagnosis your doctor may obtain scrapings of affected skin or clippings of affected nails. These may be examined under a microscope and may be sent to the laboratory for a fungal culture. Keep in mind that the results of the fungal culture may not be available for 2-4 weeks.


Spread usually occurs through direct contact with an infected person or animal. Clothing, bedding and towels can also become contaminated and spread the infection.


Good hygiene, such as regular handwashing, is important. People should avoid sharing hairbrushes, hats and other articles of clothing that may come into contact with infected areas. Pets with signs of skin disease should be evaluated by a veterinarian. Beauty salons and barbershops should disinfect instruments with approved disinfectants after each use. Contact your local and/or state health department for specific guidelines and regulations in your area.


The particular medication and duration of treatment is based on the location of the infection. Scalp infections usually require treatment with an oral antifungal medication. Infections of other areas of skin are usually treated with topical antifungal medications. Nail infections can be challenging to treat, and may be treated with oral and/or topical antifungal medications.



Centers for Disease Control and Prevention, USA.