Epidemiology of onychomycosis

Ref ID: 19465

Author:

J. Brasch

Author address:

Universit€atsklinikum Schleswig-Holstein, Kiel, Germany

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Epidemiology of onychomycosis comprises the patterns, causes and
effects of this disease in defined populations. Onychomycosis is
undoubtedly one of the most common infectious diseases globally
and appears to be still rising. Although not life threatening, onycho-
mycosis can significantly impair quality of life. Transmission usually
occurs indirectly via contaminated floor spaces or soil surfaces. How-
ever, there is some variety in prevalence, clinical manifestations,
agents and implications of onychomycosis that is clearly related to
geography, social conditions, patients’ characteristics and health
care. These different aspects require separate considerations that
regard their specific features. Different patterns of onychomycosis have been described. In many
cases initial or mild onychomycosis is not recognized by the affected
person, whereas extensive onychomycosis is worrying. In the plain
majority of proven infections foot nails are affected and the first toe
nail is particularly at risk. Clinically distal-lateral and proximal su-
bungual types, a superficial type, an endonyx and a dystrophic type
can be distinguished. The first one is the most frequent pattern in
most countries. Furthermore paronychia and discoloration can be
revealing features pointing to yeasts or moulds. These distinct pat-
terns of nail invasion are important for the choice of treatment.
Many different fungi can cause onychomycosis and the predomi-
nant agents are largely dependent on the specific characteristics of
the studied groups of individuals and on their environment. Typically
mycotic nail invasion is caused by dermatophytes, and the predomi-
nant species depends on the geographical region and climate. In
most regions Trichophyton (T.) rubrum is the prevailing agent, fol-
lowed by T. interdigitale. However, many other fungi can also cause
onychomycosis under appropriate conditions. This applies to a broad
panel of yeasts (Candida albicans ranking first) that appear to affect
fingernails more often than foot nails. The spectrum of moulds com-
prises Scopulariopsis brevicaulis, Acremonium, Scytalidium, Fusarium
and Aspergillus spp. plus many other species on rare occasions.
Recently attention has been drawn to the possibility that black yeast-
like fungi like Phialophora spp. can also invade nails. Therefore diag-
nostic procedures have to include suitable methods for the identifica-
tion of such rare pathogens.
The prevalence of onychomycosis within a defined population is
strongly determined by the characteristics of the studied group. Age
is clearly an important risk factor, but slow longitudinal nail growth
per se was not found to correlate with onychomycosis. In children
onychomycosis is rare, but there are increasing reports of proven
onychomycosis in youngsters. In general, close quarter living settings
are associated with a high risk of onychomycosis. Occupation can be
a decisive factor, as well as the type of footwear commonly used and
the hygienic conditions prevailing within certain segments of society.
This applies, e.g., to athletes like soccer players, miners or military
personnel. Predisposing nail alterations can facilitate secondary fun-
gal infections. The resistance to fungal invasion can be reduced by
traumatic nail destruction, psoriatic nail changes or other diseases.
In addition, the general health condition plays an important role.
The spectrum ranges from undernourished individuals living under
extremely poor conditions to individuals who benefit from highly
sophisticated health care systems. The latter may be predisposed to
onychomycosis because of old age, diseases of civilisation or iatro-
genic immunosuppression. Diabetes mellitus, reduced perfusion due
to vascular problems, hemodialysis, liver disease and HIV are known
risk factors. Recently anti-TNFalpha treatment has been reported to
facilitate onychomycosis in psoriasis patients. A genetic predisposition
for certain mycotic infections is discussed.
It follows from these considerations that a physician consulted
because of onychomycosis should not only focus on the examination
of the patient’s nail but should also take into account the determin-
ing milieu that allowed the emergence of this particular onychomy-
cosis in this individual person. Such a wider approach that integrates
epidemiological aspects will be helpful to optimize diagnostic and
therapeutic measures.

Abstract Number: w15.1

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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