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 microscopy of a potassium hydroxide preparation of a skin scraping (known as a KOH test) can confirm the diagnosis of athlete's foot and help rule out other possible causes, such as candidiasis, pitted keratolysis, erythrasma, contact dermatitis, eczema, or psoriasis. Dermatophytes known to cause athlete's foot will demonstrate multiple septate branching hyphae on microscopy.

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

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 sandals while walking through communal areas such as gym showers and locker rooms.

According to the Centers for Disease Control and Prevention, "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—shoes or boots that enclose the feet) and in shared humid environments such as communal showers, shared pools, and treatment tubs. Chlorine bleach is a disinfectant 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.

Advice often given includes:

- Avoid sharing clothing, sports equipment, towels, or sheets.

- Wash clothes in hot water with fungicidal soap after suspected exposure to ringworm.

- Avoid walking barefoot; instead wear appropriate protective shoes in locker rooms and sandals at the beach.

- Avoid touching pets with bald spots, as they are often carriers of the fungus.

To avoid misdiagnosis as nail psoriasis, lichen planus, contact dermatitis, nail bed tumors such as melanoma, trauma, or yellow nail syndrome, laboratory confirmation may be necessary. The three main approaches are potassium hydroxide smear, culture and histology. This involves microscopic examination and culture of nail scrapings or clippings. Recent results indicate the most sensitive diagnostic approaches are direct smear combined with histological examination, and nail plate biopsy using periodic acid-Schiff stain. To reliably identify nondermatophyte molds, several samples may be necessary.

There are four classic types of onychomycosis:

- Distal subungual onychomycosis is the most common form of "tinea unguium" and is usually caused by "Trichophyton rubrum", which invades the nail bed and the underside of the nail plate.

- White superficial onychomycosis (WSO) is caused by fungal invasion of the superficial layers of the nail plate to form "white islands" on the plate. It accounts for around 10 percent of onychomycosis cases. In some cases, WSO is a misdiagnosis of "keratin granulations" which are not a fungus, but a reaction to nail polish that can cause the nails to have a chalky white appearance. A laboratory test should be performed to confirm.

- Proximal subungual onychomycosis is fungal penetration of the newly formed nail plate through the proximal nail fold. It is the least common form of "tinea unguium" in healthy people, but is found more commonly when the patient is immunocompromised.

- Candidal onychomycosis is "Candida" species invasion of the fingernails, usually occurring in persons who frequently immerse their hands in water. This normally requires the prior damage of the nail by infection or trauma.

no approved human vaccine exist against "Dermatophytosis". For horses, dogs and cats there is available an approved inactivated vaccine called "Insol Dermatophyton" (Boehringer Ingelheim) which provides time-limited protection against several trichophyton and microsporum fungal strains.

Medical professionals recommend a preventative based approach of stopping fungus before it occurs. Prevention is preferable over a reactive treatment approach. The preventative based approach involves removing heat and moisture to the groin area.

- Dry off with a clean towel immediately after showering, swimming or perspiring.

- Shower after physical activities.

- Wear underwear with high air and moisture permeability fabric, such as linen (flax).

Tinea cruris is similar to, but different from Candidal intertrigo, which is an infection of the skin by "Candida albicans". The latter is more specifically located between intertriginous folds of adjacent skin, which can be present in the groin or scrotum, and be indistinguishable from fungal infections caused by "tinea". However, candidal infections tend to both appear and with treatment disappear more quickly. It may also affect the scrotum.

At the start of each wrestling meet, trained referees examine the skin of all wrestlers before any participation. During this examination, male wrestlers are to wear shorts; female wrestlers are only permitted to wear shorts and a sports bra. Open wounds and infectious skin conditions that cannot be adequately protected are considered grounds for disqualification from both practice and competition. This essentially means that the skin condition has been deemed as non-infectious and adequately medicated, covered with a tight wrapping and proper ointment. In addition, the wrestler must have developed no new lesions in the 72 hours before the examination. Wrestlers who are undergoing treatment for a communicable skin disease at the time of the meet or tournament shall provide written documentation to that effect from a physician. This documentation should include the wrestler’s diagnosis, culture results (if possible), date and time therapy began, and the exact names of medication for treatment. These measures aren’t always successful, and the infection is sometimes spread regardless.

Keeping the skin clean and dry, as well as maintaining good hygiene, will help larger topical mycoses. Because fungal infections are contagious, it is important to wash after touching other people or animals. Sports clothing should also be washed after use.

Systemic mycoses due to opportunistic pathogens are infections of patients with immune deficiencies who would otherwise not be infected. Examples of immunocompromised conditions include AIDS, alteration of normal flora by antibiotics, immunosuppressive therapy, and metastatic cancer. Examples of opportunistic mycoses include Candidiasis, Cryptococcosis and Aspergillosis.

According to the NCAA Wrestling Rules and Interpretations, used by all high schools in the United States: "Infection control measures, or measures that seek to prevent the spread of disease, should be utilized to reduce the risks of disease transmission. Efforts should be made to improve wrestler hygiene practices, to utilize recommended procedures for cleaning and disinfection of surfaces, and to handle blood and other bodily fluids appropriately. Suggested measures include: promotion of hand hygiene practices; educating athletes not to pick, squeeze, or scratch skin lesions; encouraging athletes to shower after activity; educating athletes not to share protective gear, towels, razors or water bottles; ensuring recommended procedures for cleaning and disinfection of wrestling mats, all athletic equipment, locker rooms, and whirlpool tubs are closely followed; and verifying clean up of blood and other potentially infectious materials." More ways of prevention include wearing long sleeve shirts and sweatpants to limit

the amount of skin to skin contact. A wrestler should also not share their

equipment with other teammates and should regularly check their skin for any lesions or other signs of outbreaks. Body wipes are also common to see Coaches must also enforce the disinfecting and sanitary cleansing of the wrestling mats and other practice areas. This can greatly limit the spread of skin infections that can infect an individual indirectly.

One high school wrestling coach from Southern California described his methods of prevention using three simple procedures. “Keep the mats [clean]…you’ve got to bleach and mop them every day before practice. Along the same lines, gear should also be washed regularly, especially headgear…Most importantly, the wrestlers need to shower immediately after practices. If one kid doesn’t, and he gets [infected], it can spread to everyone else on the team within a week. I’ve had it happen before, to the point where some schools won’t allow any of our guys to wrestle in a meet. When this happens, it’s a huge blow to the school’s record and reputation. In the future, we are less likely to be invited to exclusive tournaments in the coming year.”

Bumblefoot is so named because of the characteristic "bumbles" or lesions, as well as swelling of the foot pad, symptomatic of an infection. Topical antiseptics in addition to oral or injected antibiotics may be used to combat the infection, which if left untreated may be fatal.

Diagnosis of mycetoma is usually established clinically in endemic areas.

X rays and ultrasonography may be employed in evaluating the extent of the disease. X rays findings are extremely variable. The disease is most often observed at an advanced stage that exhibits extensive destruction of all bones of the foot. Rarely, a single lesion may be seen in the tibia where the picture is identical with chronic osteomyelitis. Cytology of fine needle aspirate or pus from the lesion, and tissue biopsy may be undertaken sometimes. Some publications have claimed a "dot in a circle sign" as a characteristic MRI feature for this condition (this feature has also been described on ultrasound).

The following clinical conditions may be considered before diagnosing a patient with mycetoma:

1. Tuberculous ulcer

2. Kaposi's sarcoma, a vascular tumour of skin usually seen in AIDS.

3. Leprosy

4. Syphilis

5. Malignant neoplasm

6. Tropical ulcer

7. Botryomycosis, a skin infection usually caused by the bacteria Staphylococcus aureus.

Immersion foot syndromes are a class of foot injury caused by water absorption in the outer layer of skin. There are different subclass names for this condition based on the temperature of the water to which the foot is exposed. These include trench foot, tropical immersion foot, and warm water immersion foot. In one 3-day military study, it was found that submersion in water allowing for a higher skin temperature resulted in worse skin maceration and pain.

"Warm water immersion foot" is a skin condition of the feet that results after exposure to warm, wet conditions for 48 hours or more and is characterized by maceration ("pruning"), blanching, and wrinkling of the soles, padding of toes (especially the big toe) and padding of the sides of the feet.

Foot maceration occur whenever exposed for prolong periods to moist conditions. Large watery blisters appear which are painful when they open and begin to peel away from the foot itself. The heels, sides and bony prominences are left with large areas of extremely sensitive, red tissue, exposed and prone to infection. As the condition worsens, more blisters develop due to prolonged dampness which eventually covers the entire heel and/or other large, padded sections of the foot, especially the undersides as well as toes. Each layer in turn peels away resulting in deep, extremely tender, red ulcerations.

Healing occurs only when the feet are cleansed, dried and exposed to air for weeks. Scarring is permanent with dry, thin skin that appears red for up to a year or more. The padding of the feet returns but healing can be painful as the nerves repair with characteristics of diabetic neuropathy. Antibiotics and/or antifungal are sometimes prescribed.

Foot immersion is a common problem with homeless individuals wearing one pair of socks and shoes for extensive periods of time, especially wet shoes and sneakers from rain and snow. The condition is exacerbated by excessive dampness of the feet for prolonged periods of time. Fungus and bacterial infections prosper in the warm, dark, wet conditions and are characterized by a sickly odor that is distinct to foot immersion.

In 2016, thermography was used to identify and evaluate bumblefoot lesions in 67 captive penguins from three species.

Steps to prevent diabetic foot ulcers include frequent review by a foot specialist, good foot hygiene, diabetic socks and shoes, as well as avoiding injury.

- Foot-care education combined with increased surveillance can reduce the incidence of serious foot lesions.

Foot rot, or infectious pododermatitis, is a hoof infection commonly found in sheep, goats, and cattle. As the name suggests, it rots away the foot of the animal, more specifically the area between the two toes of the affected animal. It is extremely painful and contagious. It can be treated with a series of medications, but if not treated, the whole herd can become infected. The cause of the infection in cattle is two species of anaerobic bacteria, "Fusobacterium necrophorum" and "Bacteroides melaninogenicus". Both bacteria are common to the environment in which cattle live, and "Fusobacterium" is present in the rumen and fecal matter of the cattle. In sheep, "F. necrophorum" first invades the interdigital skin following damage to the skin, and causes interdigital lesions and slight inflammation. The second stage of the disease is marked by the invasion of the foot by the foot rot bacterium "Dichelobacter nodosus", a Gram-negative anaerobe. Usually, an injury to the skin between the hooves allows the bacteria to infect the animal. Another cause of foot rot may be high temperatures or humidity, causing the skin between the hooves to crack and let the bacteria infect the foot. This is one of the reasons foot rot is such a major problem in the summer. Foot rot is easily identifiable by its appearance and foul odor. Treatment is usually with an antibiotic medication, and preventing injury to the feet is the best way to prevent foot rot.

The disease is different in cattle and sheep and cross-infection is not thought to occur.

Scaly foot, or knemidocoptiasis is a bird ailment that is common among caged birds and also affects many other bird species. It is caused by mites in the genus "Knemidocoptes" which burrow into the bird's flesh. The tunnels made by the mites within the skin cause dermatitis and scaly lesions. Scaly face is caused by the same mite responsible for scaly foot and other related mites cause depluming. The condition is transmitted from one bird to another by direct prolonged contact.

The first sign of a foot-rot infection is when the skin between the claws of the hoof begins to swell (cellulitis). Swelling usually appears 24 hours after infection. The skin between the toes may be very red and tender and the toes may separate because of all the swelling. This is very painful to the animal and can cause lameness. The animal may also have a raised body temperature. A crack can develop along the infected part and is yellow in color. The foot will have a foul odor. Tendons and joints in the area can become infected, which is much harder to treat. A condition known as "super foot rot" is seen in some animals. Super foot rot infection occurs much faster and is usually much more severe. Most normal foot rot treatments will not cure this foot rot and a veterinarian should be contacted immediately.

Vaccines have been developed, but their efficacy is questionable and the immunity they provide is of short duration.

Diagnosis is clinical. Sensation is tested using graded monofilament.

Scaly foot, otherwise known as knemidocoptiasis, is caused by burrowing mites in the genus "Knemidocoptes". The condition can be compared with sarcoptic mange in mammals, but does not seem to cause the same level of itching. The birds chiefly affected are galliformes (chickens and turkeys), passerines (finches, canaries, sparrows, robins, wrens), and psittacine birds (parrots, macaws, parakeets, budgerigars). The condition sometimes additionally affects piciformes (woodpeckers, toucans) and anseriformes ducks, geese, swans), raptors and other birds. The two species of mite most often implicated are "K. jamaicensis" and "K. intermedius". Other related species of mite affect feather follicles and cause depluming. The mites are mostly transmitted by prolonged direct contact, particularly from parent bird to unfledged nestling.

Assessment of diabetic foot ulcer includes identifying risk factors such as diabetic peripheral neuropathy, noting that 50 percent of people are asymptomatic, and ruling out other causes of peripheral neuropathy such as alcohol abuse and spinal injury.

The location of the ulcer, its size, shape, depth and whether the tissue is granulating or sloughy needs to be considered. Further considerations include whether the there is malodour, condition of the border of the wound and palpable bone and sinus formation should be investigated. Signs of infection require to be considered such as development of grey or yellow tissue, purulent discharge, unpleasant smell, sinus, undermined edges and exposure of bone or tendon.

Identification of diabetic foot in medical databases, such as commercial claims and prescription data, is complicated by the lack of a specific ICD-9 code for diabetic foot and variation in coding practices. The following codes indicate ulcer of the lower limb or foot:

- 707.1 Ulcer of lower limbs, except pressure ulcer

- 707.14 Ulcer of heel and midfoot

- 707.15 Ulcer of other part of foot

- 707.19 Ulcer of other part of lower limb

One or more codes, in combination with a current or prior diagnosis of diabetes may be sufficient to conclude diabetic foot:

- 250.0 Diabetes Mellitus

- 250.8 Diabetes with other specified manifestations