Athlete's foot, ringworm and jock itch can be one fungus in different places
The mould behind athlete's foot does not care where it lives. Scratched onto the hands, torso or groin, the same infection simply changes name: ringworm on the body, jock itch in the groin. Many people never realise they are dealing with one disease, and it can travel back to freshly treated feet.
Doctors call it tinea pedis. It is a fungal skin infection that usually settles between the toes, most often in the gap between the fourth and fifth, and next most often on the sole. Itching, scaling, cracking and redness are typical, and blisters appear occasionally. Around 15 percent of people worldwide have it at any time, men more than women, and it peaks among older children and young adults. It was first described medically in 1908.
The culprits are dermatophytes, mostly moulds that live in the dead outer layers of skin, digest keratin and prefer human hosts. Trichophyton rubrum causes most cases in the general population, while T. mentagrophytes is behind the majority in athletes. Despite the name, you need not play sport to catch it. Warm, damp settings such as pool surrounds, communal showers and enclosed shoes favour the fungus, and it spreads by touch, through shed skin flakes, and even via pets. It is thought to have been rare until the 20th century, when more shoe-wearing, health clubs, war and travel helped it spread.
Scratching makes things worse. It can break the skin, invite bacterial infection, and carry the fungus to fingers and fingernails. Left alone long enough, the infection can move into the toenails, a condition called onychomycosis. Some people also develop an id reaction, an allergic response that brings blisters on the hands, chest or arms and usually fades once the foot infection is treated. Diabetes, a weakened immune system and heavy sweating all raise the risk.
Diagnosis is normally made by looking at the skin. When there is doubt, a skin scraping treated with potassium hydroxide can reveal branching fungal threads under a microscope. A black light, handy for scalp fungus, is of little use here because these species do not glow under ultraviolet. Treatment described in the sources includes antifungal creams such as clotrimazole, typically used for four weeks, and tablets such as terbinafine for stubborn cases.
Source: Athlete's foot
