Tinea corporis is caused by a tiny fungus known as dermatophyte. These tiny organisms normally live on the superficial skin surface, and when the opportunity is right, they can induce a rash or infection.

The disease can also be acquired by person-to-person transfer usually via direct skin contact with an infected individual. Animal-to-human transmission is also common. Ringworm commonly occurs on pets (dogs, cats) and the fungus can be acquired while petting or grooming an animal. Ringworm can also be acquired from other animals such as horses, pigs, ferrets and cows. The fungus can also be spread by touching inanimate objects like personal care products, bed linen, combs, athletic gear, or hair brushes contaminated by an affected person.

Individuals at high risk of acquiring ringworm include those who:

- Live in crowded, humid conditions.

- Sweat excessively, as sweat can produce a humid wet environment where the pathogenic fungi can thrive. This is most common in the armpits, groin creases and skin folds of the abdomen.

- Participate in close contact sports like soccer, rugby, or wrestling.

- Wear tight, constrictive clothing with poor aeration.

- Have a weakened immune system (e.g., those infected with HIV or taking immunosuppressive drugs).

Because fungi prefer warm, moist environments, preventing ringworm involves keeping skin dry and avoiding contact with infectious material. Basic prevention measures include:

- Washing hands after handling animals, soil, and plants.

- Avoiding touching characteristic lesions on other people.

- Wearing loose-fitting clothing.

- Practicing good hygiene when participating in sports that involve physical contact with other people.

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.

The transmission of Tinea Barbae to humans occurs through contact of an infected animal to the skin of a human. Infection can occasionally be transmitted through contact of infected animal hair on human skin. Tinea Barbae is very rarely transmitted through human to human contact but is not completely impossible.

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.

Tinea capitis caused by species of "Microsporum" and "Trichophyton" is a contagious disease that is endemic in many countries. Affecting primarily pre-pubertal children between 6 and 10 years, it is more common in males than females; rarely does the disease persist past age sixteen. Because spread is thought to occur through direct contact with afflicted individuals, large outbreaks have been known to occur in schools and other places where children are in close quarters; however, indirect spread through contamination with infected objects ("fomites") may also be a factor in the spread of infection. In the USA, tinea capitis is thought to occur in 3-8% of the pediatric population; up to one-third of households with contact with an infected person may harbor the disease without showing any symptoms.

The fungal species responsible for causing tinea capitis vary according to the geographical region, and may also change over time. For example, "Microsporum audouinii" was the predominant etiological agent in North America and Europe until the 1950s, but now "Trichophyton tonsurans" is more common in the USA, and becoming more common in Europe and the United Kingdom. This shift is thought to be due to the widespread use of griseofulvin, which is more effective against "M. audounii" than "T. tonsurans"; also, changes in immigration patterns and increases in international travel have likely spread "T. tonsurans" to new areas. Another fungal species that has increased in prevalence is "Trichophyton violaceum", especially in urban populations of the United Kingdom and Europe.

According to the National Health Service, "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 tinea corporis ("ringworm") when the torso or limbs are affected or tinea cruris (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.

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. Hyperhidrosis (abnormally increased sweating) increases the risk of infection and makes treatment more difficult.

Main symptoms that occur when affected with Tinea Barbae is pimple or blister amongst affected area, swelling and redness around infected area, red and lumpy skin on infected area. Crusting around hairs in infected area will occur, hairs on infected area will also be effortless to pull out. Tinea Barbae can be itchy or painful to touch but these symptoms do not always occur.

It may appear as thickened, scaly, and sometimes boggy swellings, or as expanding raised red rings (ringworm). Common symptoms are severe itching of the scalp, dandruff, and bald patches where the fungus has rooted itself in the skin. It often presents identically to dandruff or seborrheic dermatitis. The highest incidence in the United States of America is in American boys of school age.

There are three type of tinea capitis, microsporosis, trichophytosis, and favus; these are based on the causative microorganism, and the nature of the symptoms. In "microsporosis", the lesion is a small red papule around a hair shaft that later becomes scaly; eventually the hairs break off 1–3 mm above the scalp. This disease used to be caused primarily by "Microsporum audouinii", but in Europe, "M. canis" is more frequently the causative fungus. The source of this fungus is typically sick cats and kittens; it may be spread through person to person contact, or by sharing contaminated brushes and combs. In the United States, "Trichophytosis" is usually caused by "Trichophyton tonsurans", while "T. violaceum" is more common in Eastern Europe, Africa, and India. This fungus causes dry, non-inflammatory patches that tend to be angular in shape. When the hairs break off at the opening of the follicle, black dots remain. "Favus" is caused by "T. schoenleinii", and is endemic in South Africa and the Middle East. It is characterized by a number of yellowish, circular, cup-shaped crusts (scutula) grouped in patches like a piece of honeycomb, each about the size of a split pea, with a hair projecting in the center. These increase in size and become crusted over, so that the characteristic lesion can only be seen around the edge of the scab.

Unlike most other manifestations of Tinea dermatophyte infections, Kerion is not sufficiently treated with topical antifungals and requires systemic therapy. Typical therapy consists of oral antifungals, such as griseofulvin or terbinafine, for a sustained duration of at least 6-8 weeks depending on severity. Successful treatment of kerion often requires empiric bacterial antibiotics given the high prevalence of secondary bacterial infection.

A dermatomycosis is a skin disease caused by a fungus. This excludes dermatophytosis.

Examples of dermatomycoses are tinea and cutaneous candidiasis.

Current worldwide prevalence has been very approximately estimated at two percent of the human population. Accurate numbers are difficult to acquire, because pubic lice infestations are not considered a reportable condition by many governments, and many cases are self-treated or treated discreetly by personal physicians.

Although any part of the body may be colonized, crab lice favor the hairs of the genital and peri-anal region. Especially in male patients, pubic lice and eggs can also be found in hair on the abdomen and under the armpits, as well as on the beard and mustache, while in children they are usually found in eyelashes.

It has recently been suggested that an increasing percentage of humans removing their pubic hair has led to reduced crab louse populations in some parts of the world.

Kerion is the result of the host's response to a fungal ringworm infection of the hair follicles of the scalp (occasionally the beard) that can be accompanied by secondary bacterial infection(s). It usually appears as raised, spongy lesions, and typically occurs in children. This honeycomb is a painful inflammatory reaction with deep suppurative lesions on the scalp. Follicles may be seen discharging pus. There may be sinus formation and rarely mycetoma-like grains are produced. It is usually caused by dermatophytes (fungal infections of the skin affecting humans and animals) such as "Trichophyton verrucosum", "T. mentagrophytes", and "Microsporum canis". Treatment with oral griseofulvin common.

Sycosis vulgaris (also known as "Barber's itch," and "Sycosis barbae") is a cutaneous condition characterized by a chronic infection of the chin or bearded region. The irritation is caused by a deep infection of hair follicles, often by species of "Staphylococcus" or "Propionibacterium" bacteria. Asymptomatic or painful and tender erythematous papules and pustules may form around coarse hair in the beard (sycosis barbae) or the back of the neck (sycosis nuchae).

Razor burn is a less serious condition caused by shaving, characterized by mild to moderate redness and irritation on the surface of the skin. Unlike PFB, it is usually transient and there is no infection involved.

There is also a condition called "folliculitis barbae". The difference between the two is the cause of the inflammation in the hair follicles. Folliculitis barbae is caused by viral or bacterial infections, where pseudofolliculitis is caused by irritation from shaving and ingrown hairs.

A related condition, pseudofolliculitis nuchae, occurs on the back of the neck, often along the posterior hairline, when curved hairs are cut short and allowed to grow back into the skin. Left untreated, this can develop into acne keloidalis nuchae, a condition where hard, dark keloid-like bumps form on the neck. Both occur frequently in black men in the military, where it is so common that services often have widely known protocols for management

Pubic lice are usually acquired by sexual activity Adults are more frequently infested than children. As with most sexually transmitted pathogens, they can only survive a short time away from the warmth and humidity of the human body.

Infestation in a young child or teenager may indicate sexual abuse.

Fiddler’s neck does not usually form unless the musician is practicing or playing for more than a few hours each day, and only seems to develop after a few years of serious playing. Thus, when not infected or otherwise problematic, fiddler’s neck may be known as a benign practice mark and may be worn proudly as an indication of long hours of practice. Blum & Ritter (1990) found that 62% of 523 professional violinists and violists in West Germany experienced fiddler’s neck, with the percentage among violists being higher (67%) than among violinists (59%). Viola players are believed to be more predisposed to developing fiddler’s neck than violinists because the viola is larger and heavier, but this has not been empirically confirmed.

The development of fiddler’s neck does not depend on preexisting skin problems, and Blum & Ritter find that only 23% of men and 14% of women in their study reported cutaneous disorders in other parts of the face (mainly acne and eczema) that were independent of playing the violin or viola. Fiddler’s neck may exacerbate existing acne, but acne may also be limited solely to the lesion and not appear elsewhere. Nonetheless, musicians with underlying dermatologic diseases like acne and eczema are more endangered by fiddler’s neck than others. Males may develop folliculitis or boils due to involvement of beard hair.

With no particular affinity to any particular ethnic group, seen in all age groups and equally amongst males and females, the precise prevalence is not known.

The most effective prevention is to grow a beard. For men who are required to; or simply prefer to shave, studies show the optimal length to be about 0.5 mm to 1 mm to prevent their hair growing back into the skin. Using a beard trimmer at the lowest setting (0.5mm or 1mm) instead of shaving is an effective alternative. The resulting faint stubble can be shaped using a standard electric razor on non-problematic areas (cheeks, lower neck).

For most cases, completely avoiding shaving for three to four weeks allows all lesions to subside, and most extrafollicular hairs will resolve themselves in about ten days.

Permanent removal of the hair follicle is the only definitive treatment for PFB. Electrolysis is effective but limited by its slow pace, pain and expense. Laser-assisted hair removal is effective. There is a risk of skin discoloration and a very small risk of scarring.

Exfoliation with various tools such as brushes and loofahs also helps prevent bumps.

Some men use electric razors to control PFB. Those who use a razor, should use a single blade or special wire-wrapped blade to avoid shaving too closely, with a new blade each shave. Shaving in the direction of hair growth every other day, rather than daily, may improve pseudofolliculitis barbae. If one must use a blade, softening the beard first with a hot, wet washcloth for five minutes or shave while showering in hot water can be helpful. Some use shaving powders (a kind of chemical depilatory) to avoid the irritation of using a blade. Barium sulfide-based depilatories are most effective, but produce an unpleasant smell.

The best form of prevention is to determine whether shaving or waxing irritates the skin and hair worse.When shaving, there are a few precautions that can be taken to prevent ingrown hairs including proper shaving techniques and preparation of the skin before shaving. When shaving, applying the proper amount of lubrication (in the form of shaving cream, gel, or soap) is important to prevent the hair from being forced underneath the surface of the skin. Also the application of too much force with a razor can contribute to hair that is cut shorter than the surrounding dermis. Using a beard trimmer at the lowest setting (1 mm or 0.5 mm) instead of shaving is an effective alternative.

Alternatively, ingrown hair can be prevented by removing the hair permanently, e.g. by laser hair removal or hair removal through electrolysis.

Other rashes that occur in a widespread distribution can look like an id reaction. These include atopic dermatitis, contact dermatitis, dyshidrosis, photodermatitis, scabies and drug eruptions.

Symptoms include rash, itching skin, and hair which remains in spite of shaving. The site of the ingrown hair will form a reddish, raised bump, similar in appearance to a pimple.

The most important infectious skin diseases of cats is ringworm or dermatophytosis. Other cat skin infections include parasitic diseases like mange and lice infestation.

Other ectoparasites, including flea and tick infestations are not considered directly contagious but are acquired from an environment where other infested hosts have established the parasite's life cycle.

Another common skin infection is cat bite abscess. A mixture of bacteria introduced by a bite wound cause infections in pockets under the skin and affected cats often show manic depression and fever.

Lupoid sycosis is a cutaneous condition that is characterized by a scarring form of deep folliculitis, typically affecting the beard area.