Nail fungal infections

Summary

• Superficial fungal infestations may affect the skin and nails.
• Fungal infections may occur all over the body.
• Some people are more susceptible to fungal infections than others.
• Some people may be carriers of fungi, but are symptom free.
• If left untreated, fungal infections may cause discomfort and pain.
• Fungi may be present on the skin without causing an infection.

Description

Superficial fungal infestations occur as infections of the skin and nails. They are caused by fungi that are everywhere around us. Fungi thrive in warm, moist conditions.

Fungal infection of the nails, tinea unguium, affects toenails more often than fingernails because toenails provide an ideal environment for fungal growth – warm, moist conditions. Toenails also grow more slowly, giving the fungal infection time to develop. When a fungus invades a fingernail or toenail, the nail (nail plate) as well as the skin under the nail (nail bed) is affected.

Fungi can be passed on quite easily from one person to another, but this does not mean that the fungus will necessarily infect the other person. Some people are more susceptible to fungal infections. In these people the presence of fungi on the body will result in fungal infections.

Fungi can live on people, objects or animals for several months.

Cause

Toenails in particular offer fungi warm, moist conditions. Athlete’s foot refers to fungal infection between the toes. The skin is red, scaly and macerated (white due to moisture).

Three types of fungi are responsible for fungal nail infections:

• Dermatophytes (mostly toenails)
• Yeast – grows in areas of warm, moist skin, such as skin folds, and on the fingernails
• Moulds or non-dermatophytes – on the skin and nails (these organisms commonly grow in soil)

Toenails injured by too much trimming or by ingrowing may become infected with fungi. A person whose feet perspire excessively runs a greater risk of fungal infection of the toenail. The possibility of fungal infection is greater if you wear socks or stockings made of synthetic fibres, or shoes with rubber instead of leather soles, or if you walk barefoot around swimming pools, showers and locker rooms.

Fungal infections of the fingernails may result from overexposure to water and detergents. The moisture that gets trapped under the nails encourages fungal growth.

Nails that are continually exposed to a warm, moist environment may develop a fungal infection on the nail or under its outer edge (onychomycosis). When the nail becomes separated from the skin underneath it, the condition is called onycholysis.

Symptoms

Symptoms may include the following:

• A distinct white or yellow spot on the nail that gradually spreads over the entire nail
• Discoloured, damaged, splitting, brittle, thickened and rough nails
• Cracking of nails
• Build-up of debris (nail fragments and pieces of skin) under the nail
• Red, itchy or swollen surrounding skin
• Athlete’s foot occurring simultaneously

If the skin under the nail is infected (distal subungual onychomycosis), the following symptoms may appear:

• Yellow streaks in the nail bed and on the under side of the nail (nail plate)
• Build-up of debris (nail fragments and pieces of skin) under the nail
• Discolouration of the entire nail and separation of the nail from the nail bed (onycholysis) – severe infections
• Brittle and broken nails

If the nail surface is infected (white superficial onychomycosis), there may be:

• White spots or white streaks on the nail surface
• A soft and powdery nail surface
• Damage to the nail, crumbling and brown or grey discolouration

With Candida onychomycosis, the symptoms vary. This infection usually occurs in the fingernails. The following symptoms may appear:

• Opaque, greenish or brownish nails
• Oddly shaped nails
• Thick nails
• Infection of the nail fold skin may cause pain
• Infection of all nails
• Pain (the only type of fungal nail infection that may be painful)

If the base of the nail is infected (proximal subungual onychomycosis), the following symptoms may appear:

• Whitish appearance of the nail base
• Opaque nails

Prevalence

Only about 50% of all nail diseases and disorders are due to fungal infection. More adults than children get fungal nail infections. Of all fungal nail infections, about 80% are of the big toenail and 20% of the fingernails. Men get infections caused by dermatophytes more often than women do, and women get yeast infections more often than men do. Moulds are more prevalent in humid, tropical climates and dermatophytes more in mild climates.

Course

Untreated nail infections can lead to unsightly and painful nails and fingers. If left untreated, fungal nail infections may become worse, other parts of the nails and/or other nails may become infected and the skin around the nail becomes infected. Nails may become odd in shape and appearance, even after treatment.

Some fungal nail infections progress very slowly, but others develop rapidly, especially in warm and damp conditions.

Risk factors

• As people get older, their nails thicken and grow more slowly, making them more susceptible to infection.
• A person whose feet perspire excessively is at greater risk of getting toenail infections.
• The likelihood of infections increases if one wears socks or stockings made of synthetic fibres; tight, ill-fitting shoes; shoes with rubber instead of leather soles; or if one walks barefoot around swimming pools, showers and locker rooms.
• Poor blood circulation due to disease may increase the risk of infection.

When to see a doctor

Call your doctor if:

• A nail is severely discoloured, damaged or thickened
• There is a build-up of pieces of skin and nail fragments under the nail
• There are signs of a bacterial infection such as increased pain, swelling, redness, tenderness and heat; red streaks extending from the area; a discharge of pus; and a fever with no other identifiable cause
• The infection is spreading
• The condition is painful

Diagnosis

Fungal nail infections are diagnosed on the basis of a medical history, a test of a sample of the debris under the nail, or a nail sample scraped or cut from the nail.

• A KOH (potassium hydroxide) preparation can determine if a fungus is causing the condition. This test is done in a clinic or a doctor’s surgery.
• A fungal culture may be done to determine if a fungus is causing the condition and which fungus may be the cause.
• Rarely, the doctor may take a skin biopsy for a microscopic study.

Treatment

Home treatment

Home treatment of fungal infections focuses on preventing reinfection and spreading of the infection.

Medication

For fungal toenail infection, griseofulvin is used to prevent the fungus from spreading while the new toenail grows out, a process that can take at least a year. This medication does not kill the fungus.

Griseofulvin is seldom used for treatment of nail infection.  More potent oral medications are now available. These medications are absorbed into a person’s blood at levels that can penetrate a nail and destroy the fungus. Treatment usually lasts for 6-12 weeks. These medications are itraconazole, terbinafine and fluconazole. The first two can treat a wide range of fungal infections, while fluconazole works best for one specific type of fungus.

An anti-fungal cream may be prescribed to confine the infection.

Surgery

In the case of fungal nail infections, removal of the nail may be indicated if the infection is severe and painful or if oral anti-fungal medication would interfere with other medication you may be taking, for example blood thinners, seizure medication and some allergy medication. In the case of recurrent infections, the nail root may be removed permanently.  Surgery should only be used as a last resort.

Prevention

• Keep the nails clean and dry. Dry the feet well after a bath or shower, especially between the toes.
• Change socks at least daily, or more often if your feet perspire excessively.
• Do not over-trim nails, or pick at and poke around the toenails; prevent minor injury which might provide an entry point for fungi.
• Do not wear tight or ill-fitting shoes.
• Try not to wear the same pair of shoes for two days in a row. Give a pair of shoes time to dry out.
• Do not share shoes with someone else.
• Do not walk barefoot in public or shared showers or locker rooms. Wear shower sandals or shower shoes.
• Treat other infections such as athlete’s foot.

Reviewed by Prof H.F. Jordaan, MBChB, MMed (Derm).