Fungal nail infections

Fungal infection of the nails is known as onychomycosis (or in some cases tinea unguium). 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 exist everywhere in our environment and on our bodies, and do not normally cause disease. Fungi can live for months on people, objects or animals, and are easily passed between people; however, not everybody will become infected. Some people are particularly vulnerable to infection, e.g. those with impaired immune systems.

Three types of fungi are responsible for fungal nail infections:

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

Nails that are continually exposed to a warm, moist environment may develop a fungal infection on the nail or under its outer edge. The moisture that gets trapped under the nails encourages fungal growth.

Toenails, in particular, offer fungi the warm, moist conditions in which they thrive. Toenails also grow more slowly than fingernails, giving the fungal infection time to develop.

When the nail becomes separated from the skin underneath it, the condition is called onycholysis.

Symptoms may include the following:

• A distinct white or yellow spot on the nail that gradually spreads over the entire nail
• Yellow streaks in the nail bed and on the underside of the nail (nail plate)
• White spots or white streaks on the nail surface
• White nail base
• A soft and powdery nail surface
• Opaque nail
• Discoloured, damaged, splitting, brittle, thickened and rough nails
• Cracking or crumbling of nails
• Build-up of debris (nail fragments and pieces of skin) under the nail
• In severe infections, discolouration of the entire nail and separation of the nail from the nail bed (onycholysis)
• Red, itchy or swollen surrounding skin
• Athlete’s foot occurring simultaneously

With candidal onychomycosis (infection by the Candida fungus), 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

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 occur more in mild climates.

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, as may the skin around the nail. 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.

• 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; or shoes with rubber instead of leather soles.
• Walking barefoot around swimming pools, showers and locker rooms also increases the risk of infection.
• Poor blood circulation due to disease may also increase your risk.

·         Toenails injured by too much trimming or by ingrowing may be prone to infection with fungi.

·         Fungal infections of the fingernails may result from overexposure to water and detergents.

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.

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 it may be. This is performed on a specimen of nail (a clipping is taken).
• Rarely, the doctor may take a skin biopsy for a microscopic study.

Home treatment focuses on stopping the spread of the infection and preventing re-infection:

·         Vacuum or steam-clean floors and soft furnishings that may be contaminated.

·         Clean floors with dilute bleach.

·         A veterinarian can check your pets for signs of infection.

Medication may also be prescribed:

·         Potent oral medications are now available. Itraconazole, terbinafine and fluconazole are absorbed into a person’s blood at levels that can penetrate a nail and actively kill the fungus. Treatment usually lasts for six to 12 weeks.

·         In some cases of fungal toenail infection, griseofulvin may be 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.

·         An anti-fungal cream may be prescribed to confine the infection. In some cases, a cortisone cream may also be added. In cases where the nails are very thick, creams containing urea may be used to thin the nail and make treatment more effective.

It is important to note that all of these drugs may interact with many other types of medication.

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.

It is important to be patient, as it takes many months for nails and especially toenails to grow out.

Prevention

• Keep the nails clean and dry. Dry the feet well after a bath or shower, especially between the toes.
• Wear open shoes whenever possible.
• 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 24 hours to dry out.
• Do not share shoes or nail clippers 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 Dr B Tod MBBCh (Wits), July 2011