Ringworm Fungal Infections – Skin Fungus

A ringworm is a superficial fungal infection of the skin that causes mild irritation, itching and cracking of the skin. A skin fungus is commonly called a ringworm due to the round or oval shape of the skin lesion with a red raised border. While a fungal infection of the skin can be treated, it often returns, especially in certain seasons.

Ringworm Causes

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A fungus is a parasite that consumes dead matter and there are two types of fungi that may infiltrate the body’s tissues.

  1. Dermatophytes
  2. Yeasts
  3. Molds

In skin fungal infections, dermatophytes are usually responsible and the most common species that affect human skin include Microsporum, Trichopyton and Epidemophyton species. Tinea is the medical term for any dermatophyte fungal infection of the skin. The outer (superficial) layers of the skin are made up of dead skin cells and prone to fungal infections if there is any break in the skin, either due to injury like cuts or other skin diseases that affect the integrity of the skin. A skin fungus, like all fungi, need three pre-existing conditions in order to thrive on the affected area.

  1. Darkness or low light intensity, especially from sunlight
  2. Warmth
  3. Moisture

Due to the need for these three life sustaining factors, a skin fungus usually thrives on the feet (athlete’s foot), groin (jock itch) and breast (breast fungus). Fungal infections are also more common in tropical environments with a warm, humid climate and high fungal spore count. A skin fungus is not isolated to the skin of the body and can also infiltrate the hair, fingernails (refer to Acrylic Nail Fungus) and toe nail.

A fungal infection is often spread from one person to another if the ideal conditions exist and in the presence of any break in the skin. It is common in locker room showers, public toilet facilities and when sharing underwear, including socks. A fungus will develop a spore to survive any difficult conditions, like the lack of a suitable substrate, and these spores can easily travel through clothing, water or even through the air. Upon landing on a suitable substrate, the spore will hatch (germinate) and begin to consume any dead matter in the area.

While a skin fungus usually exists only in the superficial areas of the skin, it can infiltrate deeper tissue in immunocompromised patients especially in conditions like HIV/AIDS (oral thrush or mouth fungus is caused by an yeast, Candida albicans).

Signs and Symptoms of a Ringworm

A ringworm may often present similar to other skin conditions and it should be differentiated from other diseases before commencing treatment.

  • Round to oval skin lesion with red raised borders.
  • Dry, cracking and red to white skin in the center of the lesion. Often the center of the lesion may appear like normal, healthy skin.
  • Tiny fluid filled blisters (vesicles) when the infection is severe or complicated by a secondary bacterial infection. Discharge may be clear and sticky or yellow in severe infections.
  • Itching, often aggravated by heat, moisture or perspiration.
  • Flaking skin, fine dust-like appearance when scratching.
  • Dark discoloration of the skin may occur in prolonged skin fungal infections that are eventually treated.

Types of Skin Fungus

A fungal infection of the skin is labeled according to the area infected and while any area of the skin is prone to a fungus, certain regions of the body are more susceptible.

Tinea pedis (Foot Ringworm)

This is the most common skin fungus and usually affects the area between the toes, sides of the feet and soles. The toe nail may also be affected (tinea unguium) and is often difficult to treat as it occurs under the nail, on the nail bed.

If left untreated, the toe nail will eventually thicken, darken and distort. Fungal infections on the web of the toes may appear white or even green after a long period of time and causes severe peeling and ulceration of the skin.

Tinea cruris (Groin Ringworm)

This type of skin fungal infection usually occurs at the area between the gentials and thigh (crural fold). It may spread and extend to the inner thigh or even onto the scrotum in males. In severe cases, it may spread to the buttocks (bottom) or towards the anus. While tinea cruris more often occurs in males, it can also occur in women, particularly overweight or obese women due to the extra folds of the skin.

Wearing tight underwear often aggravates the infection and a darkish discoloration of the skin is common.

Tinea capitis (Scalp Ringworm)

Ringworm of the scalp mainly affects children and often damages the hair, causing it to break. Usually the infection is isolated to small areas of the scalp causing ring-like patches with tiny black dots which are remnants of the broken hair shafts. If untreated, the infection may spread to the entire scalp and is among the more common causes of hair loss in children.

Tinea capitis should not be confused with dandruff which is an eczema of the head (seborrheic dermatitis) often complicated with an yeast fungal infection caused by the fungus Pityrosporum ovale (Malassezia species).

Tinea corporis (Ringworm of the Body)

A fungal infection on any part of the body, excluding the head, face, hands, feet and groin, is referred to as tinea corporis. This ringworm infection usually starts off as many small raised spots that slowly develop into larger areas. With time, the lesion may spread further out as the central areas start to clear.

Tinea unguium (Nail Fungus)

A fungal infection of the fingernails or toe nail is one of the more persistent infections and cause deformation or disintegration of the nail. Toenail fungus often occurs as a result of a long standing athlete’s foot while a fingernail fungus is common in constant acrylic nail use. The nail becomes dull with a flaky or powdery appearance and sometimes the nail bed may be damaged as well.

Tinea barbae (Beard Ringworm)

A fungal infection of the face or neck particularly in the area of a beard which mainly occurs in males. Also known as barber’s itch, this infection is common in men with ingrown hairs or folliculitis. Breaks in the skin, often caused by shaving, are prone to bacterial or fungal infections.

Submammary candidiasis (Breast Fungus)

This infection occurs at the junction of the breast and chest, or fold under the breast. It is prevalent in women with larger busts or using tight brassieres that may cause breaks in the skin (intertrigo). As the name suggest, it is an yeast infection caused by the Candida species of fungi which is usually occurring naturally on the skin.

Tinea versicolor (Upper Body Fungus)

Tinea versicolor is a fungal infection of the upper body body by an yeast that causes typical pale or white patches. It usually affects the more oily parts of the skin like the neck, chest, shoulders, upper arms and back. This condition is more common in teenagers and young adults, usually due to the oily skin type associated with puberty and early adulthood.

Ringworm Treatment

In most skin fungal infections, a topical application (ciclopirox, econazole, miconazole, oxiconazole or terbinafine) is usually sufficient for treating the infection. However in severe infections, an oral antifungal drug (itraconazole, fluconazole, ketoconazole, terbinafine) may be required. Bacterial infections should be treated by antibiotics and in severe cases, debridement may be necessary. A hydrocortisone cream may be necessary for relieving itching or any dermatitis that may be present after the fungal infection resolves.

How to Prevent a Ringworm

Preventing a fungal infection should focus on increasing airflow and reducing moisture on areas that are prone to a ringworm. In terms of athlete’s foot, the most common skin fungus, using open shoes like sandals or flip flops as often as possible, drying the feet thoroughly after bathing and using drying powders for sweaty feet is important. If you are using public shower facilities on a regular basis, it is advisable to wear plastic flip flops when bathing. Ringworm infections affecting the groin and under the breast can be prevented by using loose fitting underwear that does not cut into the skin. Any open cuts, especially on the more susceptible areas, should be treated immediately and disinfected regularly. It is never advisable to share underwear, towels or toiletries that may make contact with sensitive areas.


References

  1. Ringworm. Mayo Clinic
  2. Ringworm (Tinea). Merck
  3. Tinea pedis. DermNet NZ
  4. Cutaneous candidiasis. University of Adelaide
  5. Tinea versicolor. American Academy of Dermatology