Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2003.
Fungal infection of the nails is known as onychomycosis. It is increasingly common with increased age. It rarely affects children.
Onychomycosis can be due to:
Onychomycosis may affect one or more toenails and/or fingernails and most often involves the great toenail or the little toenail. It can present in one or several different patterns:
Candida infection of the nail plate generally results from paronychia and starts near the nail fold (the cuticle). The nail fold is swollen and red, lifted off the nail plate. White, yellow, green or black marks appear on the nearby nail and spread. The nail may lift off its bed and is tender if you press on it.
Mould infections are usually indistinguishable from tinea unguium.
Onychomycosis must be distinguished from other nail disorders such as:
Clippings should be taken from crumbling tissue at the end of the infected nail. The discoloured surface of the nails can be scraped off. The debris can be scooped out from under the nail.
Previous treatment can reduce the chance of growing the fungus successfully in culture so it is best to take the clippings before any treatment is commenced:
A nail biopsy may also reveal characteristic histopathological features of onychomycosis.
Fingernail infections are usually cured more quickly and effectively than toenail infections.
Mild infections affecting less than 50% of one or two nails may respond to topical antifungal medications but cure usually requires an oral antifungal medication for several months. Combined topical and oral treatment is probably the most effective regime.
Recently, non-drug treatment has been developed to treat onychomycosis thus avoiding the side effects and risks of oral antifungal drugs.
Lasers emitting infrared radiation are thought to kill fungi by the production of heat within the infected tissue. Laser treatment is reported to safely eradicate nail fungi with one to three, almost painless, sessions. Several lasers have been approved for this purpose by the FDA and other regulatory authorities. However, high-quality studies of efficacy are lacking and existing studies indicate that laser treatment is less medically effective than topical or oral antifungal agents.
Photodynamic therapy using application of 5-aminolevulinic acid or methyl aminolevulinate followed by exposure to red light has also been reported to be successful in small numbers of patients, whose nails were presoftened or evulsed using urea ointment for a week or so.
Iontophoresis and ultrasound are under investigation as devices used to enhance the delivery of antifungal drugs to the nail plate.
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