Athlete's foot

Athlete's foot is a fungalinfection of the skin, usually between the toes, caused by parasitic fungi.

Causes

The body normally hosts a variety of saprophyticmicroorganisms, including bacteria and fungi. Some of these are useful to the body. Pathogenicor disease causing organisms or the overgrowth of saprophitic ones can multiply rapidly and cause infection. Athlete's foot is a layman's description of a skin fungal infection. Fungal infections of the skin are called dermatophytosis. Dermatophytes may be spread from other humans (anthropophilic), animals (zoophilic) or may come from the soil (geophilic). Anthropophillic dermatophytes are restricted to human hosts and produce a mild, chronic inflammation. Zoophilic organisms are found primarily in animals and cause marked inflammatory reactions in humans who have contact with infected cats, dogs, cattle, horses, birds, or other animals. Geophilic species are usually recovered from the soil but occasionally infect humans and animals. They cause a marked inflammatory reaction, which limits the spread of the infection and may lead to a spontaneous cure but may also leave scars. Infectionsor infestations occur when dermatophytesgrow and multiply in the skin.

Classification by area

When these infections occur on the feet they are called tinea pedis. On the head, tinea capitus, the bearded areas tinea barbaethe smooth skin areas tinea corporis. In addition to dermatophytes, other classes include yeasts such as Candida albicans. An intertrigo can occur when a fold of skin, typically between the toes or fingers, but also in the underarm area, beneath pendulous breasts or in the groin area traps moisture making an ideal growth field for the fungal invader.

Deeper invasion of the tissue of the foot, so called madura footor maduramycosiscan be caused by yeast. The lumps are called mycetoma. These infections are limited to the skin but do destroy local tissues. The infections usually occur in the subtropic and tropic regions but are sometimes seen in populations with impaired immunity such as the homeless and those with AIDS. The disease is named after the region in India where it was first described in 1842.

Other fungal infections such as coccidiomycosis, psittacosisand aspergillosiscan have skin manifestations but are usually systemic infectionsassociated with the lungs.

Growth environment

Growth of the athlete's foot fungus is promoted by a dark, warm, moist environment such as that found inside shoes. The fungi persist for a long time in the environment, facilitating transmission of the disease in communal areas such as locker rooms and showers.

Symptoms

Image:Intertrigo-1.jpg Athlete's foot causes scaling and itching of the affected skin. Blisters and cracked skin may also occur, leading to exposed raw tissue, pain, swelling, and inflammation. Despite its name, the infection can be spread to other areas of the body, such as the armpits and the groin.

When the infection occurs between the toes or fingers or in any fold of skin, it is called an intertrigo.

Treatment

The infection is often treated with topical antifungalagents such as miconazole, itraconazole, terbinafineand a keratolyticsuch as salicylic acid. Topical agents only clear the infection about 30% of the time and provide mycologic cures (absence of organisms) less than 15% of the time. The time line for cure may be long, often 45 days or longer. However, because the itching associated with the infection subsides quickly, patients may not complete the courses of therapy prescribed.

Some topical applications such as Castellani's Paint, often used for intertrigo, work well but in small selected areas. Carbol Fuscin Red dye used in this treatment like many other vital stainsis both fungicidaland bacteriocidal; however, because of the staining are cosmetically undesirable. For many years gentian violetwas also used for interdigital and other bacterial and fungal infections.

Oral treatment with griseofulvinwas begun early in the 1950s. Because of the tendency to cause liver problems and to provoke aplastic anemiathe drugs were used cautiously and sparingly. Over time it was found that those problems were due to the size of the crystal in the manufacturing process and microsize and now ultramicrosize crystals are available with few of the original side effects. Oral treatment provides long lasting mycologic cure.

If the fungal invader is not a dermatophyte but a yeast, other medications such as diflucanmay be used. Typically diflucan is used for candidal vaginal infections moniliasisbut has been shown to be of benefit for those with cutaneous yeast infections as well. The most common of these infections occur in the web spaces (intertriginous) and at the base of the fingernail or toenail. The hall mark of these infections is a cherry red color surrounding the lesion and a yellow thick pus.

Remedies and folklore

Traditional remedies for athlete's foot include crocodile oilin a topical application on the affected area. Users report instant relief from itching allowing lesions to heal. Proponents of urine therapyclaim that urineis very effective at killing athlete's foot. Urea, the "active ingredient" in urine, is already used in many drugs and treatments made by pharmaceuticalcompaniesto treat athlete's foot. This controversial treatment method recommends urinating on the infected area once a day in the shower. According to supporters, urine therapynot only kills existing fungi, it prevents new fungi from growing in the infected area.

One biochemist states that urea is only used to soften the outer layers of skin so that antifungal drugs can reach fungi below the surface, and that the urea must be concentrated and applied for a long period of time in order to be effective. [1] According to another article about high-concentration urea cream, the compound is used to "dissolve proteins and [as a] denaturant. The ability of urea to macerate [tissue] has been attributed to a 'proteolytic effect', but others attribute the maceration to the hydrating properties of urea." [2] This use requires a high concentration of urea, up to 40%, and extended exposure. Urea itself without the presence of an additional antifungal drugis not referred to in scholarly literature as having antifungal properties. Thus, it is unlikely that urinating on one's feet in the shower will significantly improve a case of athlete's foot.

See also

• List of tinea infections

External links

• NIH Medline Athlete's Foot page
• Page about Urine Therapy (UT)
• eMedicine Health Athlete's Foot
• eMedicine and Mycetomade:Hautpilz

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This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article Athlete's foot.