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Background - What is skin fungus

What is skin fungus?

Fungal infections, or mycosis, are diseases caused by a fungus (parasites that include yeast and mold).

Fungal infections are most common on your skin or nails (superficial), but can also cause infections in your mouth, throat, lungs, urinary tract and many other parts of your body.

Superficial fungal infections are the 4th most common cause of disease in the human population, affect the outer layers of the skin, nails, mucous membranes, and hair and are commonly seen in everyday clinical practice.

Three main organisms are responsible for superficial fungal infections. These are:

  1. Dermatophytes: a group of fungi that digest keratin (for example, in hair and nails).
  2. Yeasts: a group of fungi characterised by clusters of round or oval cells, which bud out to divide and propagate.
  3. Moulds: commonly found widespread in the environment, and therefore are a common cause of nail infections.

Common fungal skin infections

NAMECAUSESYMPTOMSMOST COMMON IN
Tinea cruris (jock itch)1Dermatophyte, commonly spreads from infection on the feet or nailsAsymmetric rash in the groin and surrounding areasYoung men
Tinea pedis (athlete’s foot)2Dermatophyte, usually acquired from direct contact, for example, sharing towels, walking in a public changing roomAsymmetric itchy erosions or scales on feet, including between the toes, sole and sides of the footYoung men
Tinea capitis (scalp ringworm)3Dermatophyte, contagious; spread from contact with infected people or animals, or through household furniture or itemsDry, scaly areas on the scalp with alopecia, redness and itchPreadolescent children
Tinea corporis (ringworm)4Dermatophyte, affects any part of the body, except hands and feet, scalp, face and beard, groin and nails. transmission facilitated through sharing of household itemsRing-shaped lesion, with central hypopigmentation and a peripheral scaly red rimChildren and young adults
tinea-cruris

Tinea cruris

tinea-pedis

Tinea pedis

tinea-capitis

Tinea capitis

tinea-corporis

Tinea corporis

1. DermNetNZ.org. Tinea cruris.
2. DermNetNZ.org. Tinea pedis.
3. DermNetNZ.org. Tinea capitis.
4. DermNetNZ.org. Tinea corporis.

NAMECAUSESYMPTOMSMOST COMMON IN
Moccasin-type tinea pedisDermatophyte, affects the soles, heels and sides of the feetScaly, red and thickened skinYoung men
Cutaneous candidiasis1,2Candida yeasts, normal inhabitants of the human digestive tract that can cause infection if the immune system is weakened.Rash in skin foldsInfants or elderly
Tinea / pityriasis versicolor4Malassezia yeasts, fungi that are a normal part of skin microbiota but can grow more actively to form disease. Not considered infectiousFlaky, discoloured patches on the trunk, arms, or neckYoung adults
Onychomycosis (fungal nail infection)5Can be caused by dermatophytes (in over 75% of cases), or non-dermatophyte infection (NDMO) from yeasts or moulds. 10 times more common in toenails than fingernails3Single or multiple nails; can appear as scaling, crumbling or discolouration among other symptoms Adults > 65 years old
moccasin-type

Moccasin-type tinea pedis

Cutaneous-candidiasis

Cutaneous candidiasis

Tinea-pityriasis-versicolor

Tinea / pityriasis versicolor

Onychomycosis

Onychomycosis

1. DermNetNZ.org. Candida.
2. Hay RJ. Medicine 2017;45(11):707–710.
3. DermNetNZ.org. Oral candidiasis.
4. DermNetNZ.org. Pityriasis versicolor.
5. DermNetNZ.org. Fungal nail infections.

Causes of Fungal Skin Infections

Fungal disease can affect people of all age, race, sex and social background.

  • Certain infections are more common in certain groups, for example, ringworm (tinea corporis) in children and athlete’s foot (tinea pedis) in men

Conditions that promote fungi growth:

varm-humid

Warm, humid environments,

including public showers, swimming pools and locker rooms

tight-fitting

Tight-fitting clothing and shoes

that cause the skin to sweat

pets

Presence of pets and other domestic animals,

who may have asymptomatic dermatophyte infections

soil

Direct contact with cultivated fertile soil

Fun Fact: Athlete’s foot got its name not because it is only for athletes or that it afflicts men, but because the fungus that causes it are commonly found in places that athletes frequent, such as showers and locker rooms.

Lamisil: treatment of skin fungus

Tips for prevention

Many fungal infections have characteristic symptoms; however, the key diagnosis is the demonstration of the organism in the skin.
These general tips can help you avoid fungal skin infections or ease the symptoms if infection occurs:

  • Treat your feet if you have a fungal infection.
  • Keep your feet dry, especially between your toes.
  • Go barefoot to let your feet air out as much as possible when you’re home. 
  • If your feet get very sweaty, change your socks twice a day. 
  • Wear light, well-ventilated shoes.
  • Alternate pairs of shoes. Don’t wear the same pair every day so that you give your shoes time to dry after each use.
  • Protect your feet in public places.
  • Wear sandals or shoes around public pools, showers and lockers rooms.