In onychomycosis (synonyms: Mycosis of the nails; Nail fungus (onychomycosis); Tinea unguium; ICD-10 B35.1: Tinea unguium) is the fungus of the fingernails or toenails (nail fungus) caused by dermatophytes. The toenails are affected about four times more frequently. There is always an additional tinea pedis (athlete’s foot).
Onychomycosis is the most common disease of the nails.
The disease is caused by dermatophytes (filamentous fungi). In 80-90% of cases Trichophyton rubrum is the trigger, but Epidermophyton floccosum, yeasts (Candida species) or molds are also possible causative agents.
The nail affected by the fungus is either covered (type 1 infection) or atrophically destroyed (type 2 infection).
Occurrence: Onychomycosis occurs primarily in warm, moist environments, such as those found in swimming pools, saunas or showers.
Transmission of the pathogen (route of infection) occurs via contact and/or smear infection via objects infected with the pathogen, such as drying towels or clothing. Transmission is especially possible in places where people walk barefoot.
Human-to-human transmission: Yes.
Different forms of onychomycosis can be distinguished:
- Distal-lateral subungual type – the most common form; in this case, the infection spreads from the outside.
- Proximal subungual type – here the nail plate is affected from the nail matrix.
- Superficial white type (Leukonychia trichophytica) – this is a form that affects the toenails and is caused by Trichophyton interdigitale.
- Total onychodystrophy – growth and development disorder due to total infestation of the nail.
Sex ratio: males are affected slightly more often than females.
Frequency peak: The disease occurs with increasing age clustered. Children are rarely affected.
The prevalence (disease frequency) is 20-30% in the group of people over 40 years and from the age of 65 years is more than 50% (in Germany).
Course and prognosis: Onychomycosis is a harmless disease for humans. However, the disease can be very persistent and pronounced. If left untreated, onychomycosis does not regress but is progressive. If therapy is carried out consistently and for a sufficiently long time, the prognosis is good.
