Article: Onychomycosis

Onychomycosis means fungal infection of the nails. This condition may affect toe- or fingernails, but toenail infections are particularly common. The prevalence of onychomycosis is about 6-8% in the adult population. The most common type of onychomycosis, caused by dermatophytes, is technically known as tinea unguium (tinea of the nails).

Causes

Dermatophytes are the fungi most commonly responsible for onychomycosis. Two dermatophyte species, Trichophyton rubrum and Trichophyton interdigitale, cause the majority of onychomycosis cases worldwide. Other causal fungi include yeasts, e.g., Candida, and non-dermatophytic moulds, in particular members of the mould genera Scytalidium, Scopulariopsis and Aspergillus. Yeasts mainly cause fingernail onychomycosis in people whose hands are often submerged in water. Scytalidium mainly affects people in the tropics, though it persists if they later move to areas of temperate climate. Other moulds mainly affect people over the age of 60, and their presence in the nail reflects a slight weakening in its ability to defend itself against fungal invasion.

Treatment

Treatments are usually commenced after laboratory confirmation of fungal invasion based on microscopic examination and culture of nail scrapings or clippings. Systemic antifungal medications such as terbinafine and itraconazole have been shown to be effective in treating it, as have some topical nail paints. One such medicinal lacquer, NM100060 from NexMed, has successfully completed a Phase I clinical trial in the United States; treatment contains terbinafine as the active ingredient and the trial involved comparison to Lamisil creme.^[1]

As with many diseases, there are also some scientifically unverified folk or alternative medicine remedies. One of these is to apply two drops of distilled white vinegar into the cuticle, twice a day until the fungus is gone. This method does not kill the fungus, but the vinegar allegedly changes the pH (acid content) of the new nail formed in that twelve-hour period. (The scientific perspective, however, is that vinegar is unlikely to penetrate the dense keratinous tissue thoroughly enough to have any significant effect.) As the old, infected nail grows and is cut away, it is said to be replaced by an acidic nail, uninhabitable by fungi. Several months of consistent application are involved. Other scientifically unverified treatments include the application of tea tree oil or diluted grapefruit seed extract.

Prevention

Advice given is to keep the nails cut short and filed; to avoid trauma or irritations to the nails; to keep them cool and dry; and to wear good shoes that are not too tight or narrow.