EPIDEMIOLOGY AND ECOLOGY OF ONYCHOMYCOSIS

The epidemiology and ecology of onychomycosis are complex and little u nderstood. Most is known about tinea unguium, dermatophytic nail infec tion, and its causative agents. This is often categorised according to the precise locus on the nail of the infection. The principal infecti ous propagules are thought to be the arthroconidia or chlamydospores w hich form within the solid substratum of invaded nail tissue. The proc ess of infecting new hosts appears to be facilitated by abrasion, mois tening and scratching. The role of the non-dermatophyte yeast Candida as an agent of onychomycosis per se may have been overestimated. The r ange of interactions between dermatophytes and non-dermatophytes in na ils is complex and poorly understood. There may be at least six distin ct ecological categories of non-dermatophyte isolations from nails. It would be of clinical interest to know which species found in mixed in fections were never able to advance beyond 'secondary colonisation', a s they would not require specific treatment.