Management of Onychomycosis and Co-Existing Tinea Pedis

May 2015 | Volume 14 | Issue 5 | Original Article | 492 | Copyright © May 2015

Shari R. Lipner MD PhD and Richard K. Scher MD FACP

Weill Cornell Medical College, New York, NY

Abstract
Onychomycosis is a common nail infection that often co-exists with tinea pedis. Surveys have suggested the diseases co-exist in at least one third of patients, although actual numbers may be a lot higher due to significant under-reporting. The importance of evaluating and treating both diseases is being increasingly recognized, however, data on improved outcomes, and the potential to minimize re-infection are limited. We review a recent post hoc analysis of two large studies treating mild to moderate onychomycosis with efinaconazole topical solution, 10%, demonstrating that complete cure rates of onychomycosis are significantly improved when any co-existing tinea pedis is also treated.

J Drugs Dermatol. 2015;14(5):492-494.

INTRODUCTION

Onychomycosis is the most common fungal infection comprising about one-third of all skin fungal infections, and 50% of all nail disorders.1,2 It is well recognized in dermatology practice that onychomycosis and tinea pedis can exist together in the same patient, that tinea pedis can lead to onychomycosis, and that it is important to evaluate and treat both diseases.3 Once the nails become infected, they become reservoirs for continued infection of the surrounding skin, potentially resulting in a cycle of re-infection.4 However, data showing the impact of treating co-existing tinea pedis on onychomycosis outcomes, and the potential to reduce onychomycosis recurrence or re-infection is lacking.

Prevalence of Onychomycosis and Co-Existing Tinea Pedis

Onychomycosis has been found to be significantly more likely to be diagnosed in the context of tinea pedis (P<.001),5 with a history of tinea pedis more than doubling the risk of onychomycosis.6 Although the true prevalence of co-existing onychomycosis and tinea pedis is unknown, a number of surveys have suggested that about one third of patients with toenail onychomycosis also have tinea pedis.7-9
In a large survey of over 2700 patients with toenail onychomycosis, 42.8% had concomitant fungal infections, with tinea pedis being most common (seen in 33.8% of patients).7 Interdigital tinea pedis was the most common subtype noted in over 65.4% of cases.7
The extent of toenail onychomycosis and recurrent disease were found to be the most important parameters influencing the coexistence of tinea pedis.7 Their co-existence is more commonly seen in men, and increases with age. Not surprising as both tinea pedis and onychomyosis are more common in men; and it has been estimated that 25.7% of elderly patients have both diseases, 10 where more advanced disease, greater non-target toenail involvement, and longer disease duration are all commonplace.7 A recent study in subjects with diabetic foot complications also showed a high prevalence of both types of infection, with tinea pedis observed in 46.7% and onychomycosis in 53.3% of subjects, compared to a prevalence of 14.7% an 22.7% in matched controls.11

Treatment of Onychomycosis and the Implications of Co-Existing Tinea Pedis

Left untreated, onychomycosis and tinea pedis have the potential to cause further morbidity such as wounds, cellulitis, secondary bacterial infection, pain, and difficulty with ambulation, particularly for individuals with a compromised health status.12-14 In addition, recurrence (relapse or re-infection) of onychomycosis is not uncommon, with reported rates ranging from 10% to 53%.15-17
It is also worth mentioning that many patients with toenail onychomycosis and/or tinea pedis are not aware that they have fungal infection, and may not seek medical care and such patients pose a special challenge for physicians to detect and treat the disease.18-20
For effective onychomycosis therapy it is essential not only to treat the affected toenails but also to prevent spreading the infection to other sites of the skin. Prevention of onychomycosis includes adequate treatment of any concurrent tinea pedis, and screening and treating family members for co-existing disease.21 In addition, it has been suggested that an unnoticed and stable reservoir of dermatophytes in the nail plate can lead to infection and re-infection of the surrounding cutaneous surfaces such that effective long term cure of tinea pedis may require nail-directed therapy.5,6

Treatment of Onychomycosis and Co-Existing Tinea Pedis

Despite the clear need to look for and treat both diseases concurrently, there are few clinical data in practice to support this