Athlete's foot

Athlete's foot, known medically as tinea pedis, is a common of the feet caused by fungus. Signs and symptoms often include itching, scaling, cracking and redness. In rare cases the skin may. Athlete's foot fungus may infect any part of the foot, but most often grows between the toes. The next most common area is the bottom of the foot. The same fungus may also affect the or the. It is a member of the group of diseases known as.

Athlete's foot is caused by a number of different, including species of ', ', and . The condition is typically acquired by coming into contact with infected skin, or fungus in the environment. Common places where the fungi can survive are around swimming pools and in locker rooms. They may also be spread from other animals. Usually diagnosis is made based on signs and symptoms; however, it can be confirmed either by or seeing  using a.

Some methods of prevention include avoiding walking barefoot in public showers, keeping the toenails short, wearing big enough shoes, and changing socks daily. When infected, the feet should be kept dry and clean and wearing sandals may help. Treatment can be either with applied to the skin such as  or for persistent infections antifungal medication that are taken by mouth such as. The use of the cream is typically recommended for four weeks.

Athlete's foot was first medically described in 1908. Globally, athlete's foot affects about 15% of the population. Males are more often affected than females. It occurs most frequently in older children or younger adults. Historically it is believed to have been a rare condition, that became more frequent in the 1900s due to the greater use of shoes,, war, and travel.

Signs and symptoms
Athlete's foot is divided into four categories or presentations: chronic interdigital athlete's foot, plantar (chronic scaly) athlete's foot (aka "moccasin foot"), acute ulcerative tinea pedis, and vesiculobullous athlete's foot. "Interdigital" means between the toes. "Plantar" here refers to the sole of the foot. The ulcerative condition includes macerated lesions with scaly borders. Maceration is the softening and breaking down of skin due to extensive exposure to moisture. A is a type of  characterized by  and  (blisters). Both vesicles and bullae are fluid-filled s, and they are distinguished by size (vesicles being less than 5–10 mm and bulla being larger than 5–10 mm, depending upon what definition is used).

Athlete's foot occurs most often between the toes (interdigital), with the space between the fourth and fifth digits most commonly afflicted. Cases of interdigital athlete's foot caused by Trichophyton rubrum may be symptomless, it may itch, or the skin between the toes may appear or ulcerative (, flaky, with ), with or without itching. An acute ulcerative variant of interdigital athlete's foot caused by T. mentagrophytes is characterized by pain, maceration of the skin, erosions and fissuring of the skin, crusting, and an odor due to secondary bacterial infection.

Plantar athlete's foot (moccasin foot) is also caused by T. rubrum which typically causes asymptomatic, slightly erythematous plaques (areas of redness of the skin) to form on the plantar surface (sole) of the foot that are often covered by fine, powdery.

The vesiculobullous type of athlete's foot is less common and is usually caused by T. mentagrophytes and is characterized by a sudden outbreak of itchy blisters and on an erythematous base, usually appearing on the sole of the foot. This subtype of athlete's foot is often complicated by secondary bacterial infection by ' or '.

Complications
As the disease progresses, the skin may crack, leading to and. If allowed to grow for too long, athlete's foot fungus may spread to infect the toenails, feeding on the keratin in them, a condition called.

Because athlete's foot may, it may also elicit the , causing the host to scratch the infected area before they realize it. Scratching can further damage the skin and worsen the condition by allowing the fungus to more easily spread and thrive. The itching sensation associated with athlete's foot can be so severe that it may cause hosts to scratch vigorously enough to inflict s (open wounds), which are susceptible to bacterial infection. Further scratching may remove scabs, inhibiting the healing process.

Scratching infected areas may also spread the fungus to the fingers and under the fingernails. If not washed away soon enough, it can infect the fingers and fingernails, growing in the skin and in the nails (not just underneath). After scratching, it can be spread to wherever the person touches, including other parts of the body and to one's environment. Scratching also causes infected skin scales to fall off into one's environment, leading to further possible spread.

When athlete's foot fungus or infested skin particles spread to one's environment (such as to clothes, shoes, bathroom, etc.) whether through scratching, falling, or rubbing off, not only can they infect other people, they can also reinfect (or further infect) the host they came from. For example, infected feet infest one's socks and shoes which further expose the feet to the fungus and its spores when worn again.

The ease with which the fungus spreads to other areas of the body (on one's fingers) poses another complication. When the fungus is spread to other parts of the body, it can easily be spread back to the feet after the feet have been treated. And because the condition is called something else in each place it takes hold (e.g., (ringworm) or  (jock itch), persons infected may not be aware it is the same disease.

Some individuals may experience an allergic response to the fungus called an in which blisters or vesicles can appear in areas such as the hands, chest, and arms. Treatment of the underlying infection typically results in the disappearance of the id reaction.

Causes
Athlete's foot is a form of ( of the skin), caused by s, fungi (most of which are mold) which inhabit dead layers of skin and digest keratin. Dermatophytes are, meaning these fungi prefer human hosts. Athlete's foot is most commonly caused by the molds known as ' and ', but may also be caused by . Most cases of athlete's foot in the general population are caused by T. rubrum; however, the majority of athlete's foot cases in athletes are caused by T. mentagrophytes.

Transmission
According to the UK's, "Athlete’s foot is very contagious and can be spread through direct and indirect contact." The disease may spread to others directly when they touch the infection. People can contract the disease indirectly by coming into contact with contaminated items (clothes, towels, etc.) or surfaces (such as bathroom, shower, or locker room floors). The fungi that cause athlete's foot can easily spread to one's environment. Fungi rub off of fingers and bare feet, but also travel on the dead skin cells that continually fall off the body. Athlete's foot fungi and infested skin particles and flakes may spread to socks, shoes, clothes, to other people, pets (via petting), bed sheets, bathtubs, showers, sinks, counters, towels, rugs, floors, and carpets.

When the fungus has spread to pets, it can subsequently spread to the hands and fingers of people who pet them. If a pet frequently gnaws upon itself, it might not be fleas it is reacting to, it may be the insatiable itch of tinea.

One way to contract athlete's foot is to get a fungal infection somewhere else on the body first. The fungi causing athlete's foot may spread from other areas of the body to the feet, usually by touching or scratching the affected area, thereby getting the fungus on the fingers, and then touching or scratching the feet. While the fungus remains the same, the name of the condition changes based on where on the body the infection is located. For example, the infection is known as ("ringworm") when the torso or limbs are affected or  (jock itch or dhobi itch) when the groin is affected. Clothes (or shoes), body heat, and sweat can keep the skin warm and moist, just the environment the fungus needs to thrive.

Risk factors
Besides being exposed to any of the modes of transmission presented above, there are additional risk factors that increase one's chance of contracting athlete's foot. Persons who have had athlete's foot before are more likely to become infected than those who have not. Adults are more likely to catch athlete's foot than children. Men have a higher chance of getting athlete's foot than women. People with diabetes or weakened immune systems are more susceptible to the disease. HIV/AIDS hampers the immune system and increases the risk of acquiring athlete's foot. (abnormally increased sweating) increases the risk of infection and makes treatment more difficult.

Diagnosis
When visiting a doctor, the basic diagnosis procedure applies. This includes checking the patient's medical history and medical record for risk factors, a medical interview during which the doctor asks questions (such as about itching and scratching), and a physical examination. Athlete's foot can usually be diagnosed by visual inspection of the skin and by identifying less obvious symptoms such as itching of the affected area.

If the diagnosis is uncertain, direct of a  preparation of a skin scraping (known as a ) can confirm the diagnosis of athlete's foot and help rule out other possible causes, such as, , , , , or. s known to cause athlete's foot will demonstrate multiple septate branching on microscopy.

A (black light), although useful in diagnosing fungal infections of the scalp, is not usually helpful in diagnosing athlete's foot, since the common dermatophytes that cause this disease do not fluoresce under ultraviolet light.

Prevention
There are several preventive foot hygiene measures that can prevent athlete's foot and reduce recurrence. Some of these include keeping the feet dry, clipping toenails short; using a separate nail clipper for infected toenails; using socks made from well-ventilated cotton or synthetic moisture wicking materials (to soak moisture away from the skin to help keep it dry); avoiding tight-fitting footwear, changing socks frequently; and wearing s while walking through communal areas such as gym showers and locker rooms.

According to the, "Nails should be clipped short and kept clean. Nails can house and spread the infection." Recurrence of athlete's foot can be prevented with the use of antifungal powder on the feet.

The fungi (molds) that cause athlete's foot require warmth and moisture to survive and grow. There is an increased risk of infection with exposure to warm, moist environments (e.g., occlusive footwear&mdash;shoes or boots that enclose the feet) and in shared humid environments such as communal showers, shared pools, and treatment tubs. is a and common household cleaner that kills mold. Cleaning surfaces with a chlorine bleach solution prevents the disease from spreading from subsequent contact. Cleaning bathtubs, showers, bathroom floors, sinks, and counters with bleach helps prevent the spread of the disease, including reinfection.

Keeping socks and shoes clean (using bleach in the wash) is one way to prevent fungi from taking hold and spreading. Avoiding the sharing of boots and shoes is another way to prevent transmission. Athlete's foot can be transmitted by sharing footwear with an infected person. Hand-me-downs and purchasing used shoes are other forms of shoe-sharing. Not sharing also applies to towels, because, though less common, fungi can be passed along on towels, especially damp ones.

Treatment
Athlete's foot resolves without medication (resolves by itself) in 30–40% of cases. Topical antifungal medication consistently produce much higher rates of cure.

Conventional treatment typically involves thoroughly washing the feet daily or twice daily, followed by the application of a. Because the outer skin layers are damaged and susceptible to reinfection, topical treatment generally continues until all layers of the skin are replaced, about 2–6 weeks after symptoms disappear. Keeping feet dry and practising good hygiene (as described in the on prevention) is crucial for killing the fungus and preventing reinfection.

Treating the feet is not always enough. Once socks or shoes are infested with fungi, wearing them again can reinfect (or further infect) the feet. Socks can be effectively cleaned in the wash by adding bleach or by washing in water 60 °C (140 °F). Washing with bleach may help with shoes, but the only way to be absolutely certain that one cannot contract the disease again from a particular pair of shoes is to dispose of those shoes.

To be effective, treatment includes all infected areas (such as toenails, hands, torso, etc.). Otherwise, the infection may continue to spread, including back to treated areas. For example, leaving fungal infection of the nail untreated may allow it to spread back to the rest of the foot, to become athlete's foot once again.

s such as terbinafine are considered more efficacious than s for the treatment of athlete's foot.

Severe or prolonged fungal skin infections may require treatment with oral antifungal medication.

Topical treatments
There are many topical antifungal drugs useful in the treatment of athlete's foot including:, , (a synthetic thiocarbamate), terbinafine hydrochloride, butenafine hydrochloride and. The fungal infection may be treated with topical agents, which can take the form of a spray, powder, cream, or gel. Topical application of an antifungal cream such as once daily for one week or  once daily for two weeks is effective in most cases of athlete's foot and is more effective than application of  or. Plantar-type athlete's foot is more resistant to topical treatments due to the presence of thickened hyperkeratotic skin on the sole of the foot. and medications such as,  , and  are useful adjunct medications and improve penetration of antifungal agents into the thickened skin. Topical are sometimes prescribed to alleviate inflammation and  associated with the infection.

A solution of 1% dissolved in hot water is an alternative to antifungal drugs. Potassium permanganate is a and a strong.

Oral treatments
For severe or refractory cases of athlete's foot oral is more effective than. or may also be taken orally for severe athlete's foot infections. The most commonly reported adverse effect from these medications is gastrointestinal upset.

Epidemiology
Globally, fungal infections affect about 15% of the population and 20% of adults. Athlete's foot is common in individuals who wear unventilated (occlusive) footwear, such as rubber boots or vinyl shoes. Countries and regions where going is more common experience much lower rates of athlete's foot than do populations which habitually wear shoes; as a result, the disease has been called "a penalty of civilization". Studies have demonstrated that men are infected 2–4 times more often than women.