Fungal nail infection (onychomycosis) - Management
Introduction

  • Fungal nail infection (onychomycosis) can involve any part of, or the entire, nail unit. This includes the nail plate, nail bed, and root of the nail.
  • The infection evolves slowly. As it evolves, the nail unit discolours, the nail plate distorts, and the nail bed and adjacent tissue may thicken.
  • Fungal nail infection affects the toenails considerably more frequently than the fingernails (in a ratio of about 4:1) [Williams, 1993].
  • The organisms responsible for fungal nail infection are dermatophyte and non-dermatophyte moulds, and yeasts such as Candida — these are all fungi.
    • Dermatophyte fungal infection (tinea unguium) is responsible for about 90% of cases of onychomycosis. The common organisms are Trichophyton rubrum and Trichophyton mentagrophytes var. interdigitale [Williams, 1993].
    • Non-dermatophyte moulds such as Aspergillus, Fusarium, Scopulariopsis, and Acremonium species are responsible for about 2% of cases of toenail onychomycosis; fingernails are rarely affected [Williams, 1993].
    • Candida infection affects fingernails much more commonly than toenails. About 50% of cases of fingernail onychomycosis are due to yeasts, such as Candida albicans [Williams, 1993].
  • Fungal nail infection is common in older people, and rare in children: the prevalence in people older than 60 years of age may be as high as 30% [Williams, 1993].
  • Fungal nail infection is more common in people with certain conditions, including:
    • Fungal skin infections.
      • A survey found concomitant fungal infections of the foot (tinea pedis, 33%), groin (tinea cruris, 4%), body (tinea corporis, 2%), hand (tinea manuum, 1.5 %), and scalp (tinea capitis, 0.5%) in people with affected nails [Szepietowski et al, 2006].
    • Psoriasis.
      • A survey found that about 25% of clinically abnormal toenails in people with psoriasis were infected with fungi [Gupta et al, 1997].
    • Diabetes mellitus, peripheral vascular disease, immunocompromise [Faergemann et al, 2005].
    • Environmental factors that predispose to fungal and Candida nail infection, including [Williams, 1993]:
      • Occlusive footwear.
      • Warm, damp conditions.
      • Trauma to the nail.

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