Onychomycosis: Epidemiology, clinical features, and diagnosis
- Adam O Goldstein, MD, MPH
Adam O Goldstein, MD, MPH
- Department of Family Medicine
- University of North Carolina at Chapel Hill
- Neal Bhatia, MD
Neal Bhatia, MD
- Director of Clinical Dermatology
- Therapeutics Clinical Research
- Section Editors
- Robert P Dellavalle, MD, PhD, MSPH
Robert P Dellavalle, MD, PhD, MSPH
- Section Editor — General Dermatology
- Professor of Dermatology and Public Health
- University of Colorado School of Medicine
- Colorado School of Public Health
- Chief, Dermatology Service
- US Department of Veterans Affairs
- Eastern Colorado Health Care System
- Moise L Levy, MD
Moise L Levy, MD
- Section Editor — Pediatric Dermatology
- Professor of Pediatrics and Medicine (Dermatology)
- Dell Medical School, University of Texas, Austin
- Clinical Professor of Dermatology and Pediatrics
- Baylor College of Medicine
- Ted Rosen, MD
Ted Rosen, MD
- Section Editor — Infections and Infestations
- Professor, Department of Dermatology
- Baylor College of Medicine
Onychomycosis refers to nail infections caused by fungi, including dermatophytes (tinea unguium), yeasts, and nondermatophyte molds. The major clinical presentations of onychomycosis are distal lateral subungual onychomycosis (picture 1A-B), white superficial onychomycosis (picture 2), and proximal subungual onychomycosis (picture 3A-C). Additional clinical manifestations are endonyx onychomycosis (infection limited to the nail plate and sparing the nail bed), total dystrophic onychomycosis (picture 4), and mixed pattern onychomycosis.
The epidemiology, clinical features, and diagnosis of onychomycosis will be reviewed here. The management of onychomycosis and the differential diagnosis of nail dystrophy are reviewed separately. (See "Onychomycosis: Management" and "Overview of nail disorders".)
Onychomycosis is a common disorder that is estimated to account for 50 to 60 percent of abnormal nails . Population-based studies have found varied estimates of prevalence, ranging from less than 1 percent to 8 percent in Europe and the United States and less than 1 percent in central Africa . A systematic review of population-based studies that assessed the prevalence of culture-proven dermatophyte, yeast, and nondermatophyte mold onychomycosis of the toenails found pooled prevalences of 3.22 percent (95% CI 3.07-3.38), 0.40 percent (95% CI 0.34-0.47), and 0.37 percent, (95% CI 0.32-0.43), respectively .
Onychomycosis is much more common in adults than in children. The systematic review found pooled prevalences of pediatric dermatophyte and yeast toenail onychomycosis of 0.14 percent (95% CI 0.11-0.18) and 0.09 percent (95% CI 0.06-0.13), respectively .
Onychomycosis occurs in both sexes. Most, but not all, studies have found higher prevalences in males than in females .
- Gupta AK, Jain HC, Lynde CW, et al. Prevalence and epidemiology of onychomycosis in patients visiting physicians' offices: a multicenter canadian survey of 15,000 patients. J Am Acad Dermatol 2000; 43:244.
- Sigurgeirsson B, Baran R. The prevalence of onychomycosis in the global population: a literature study. J Eur Acad Dermatol Venereol 2014; 28:1480.
- Gupta AK, Daigle D, Foley KA. The prevalence of culture-confirmed toenail onychomycosis in at-risk patient populations. J Eur Acad Dermatol Venereol 2015; 29:1039.
- Romano C, Gianni C, Difonzo EM. Retrospective study of onychomycosis in Italy: 1985-2000. Mycoses 2005; 48:42.
- Foster KW, Ghannoum MA, Elewski BE. Epidemiologic surveillance of cutaneous fungal infection in the United States from 1999 to 2002. J Am Acad Dermatol 2004; 50:748.
- Hay RJ, Baran R. Onychomycosis: a proposed revision of the clinical classification. J Am Acad Dermatol 2011; 65:1219.
- Sigurgeirsson B, Steingrímsson O. Risk factors associated with onychomycosis. J Eur Acad Dermatol Venereol 2004; 18:48.
- Piérard GE, Piérard-Franchimont C. The nail under fungal siege in patients with type II diabetes mellitus. Mycoses 2005; 48:339.
- Muñoz-Pérez MA, Rodriguez-Pichardo A, Camacho F, Colmenero MA. Dermatological findings correlated with CD4 lymphocyte counts in a prospective 3 year study of 1161 patients with human immunodeficiency virus disease predominantly acquired through intravenous drug abuse. Br J Dermatol 1998; 139:33.
- Zaias N, Tosti A, Rebell G, et al. Autosomal dominant pattern of distal subungual onychomycosis caused by Trichophyton rubrum. J Am Acad Dermatol 1996; 34:302.
- Faergemann J, Correia O, Nowicki R, Ro BI. Genetic predisposition--understanding underlying mechanisms of onychomycosis. J Eur Acad Dermatol Venereol 2005; 19 Suppl 1:17.
- Eyerich K, Foerster S, Rombold S, et al. Patients with chronic mucocutaneous candidiasis exhibit reduced production of Th17-associated cytokines IL-17 and IL-22. J Invest Dermatol 2008; 128:2640.
- Ploysangam T, Lucky AW. Childhood white superficial onychomycosis caused by Trichophyton rubrum: report of seven cases and review of the literature. J Am Acad Dermatol 1997; 36:29.
- Piraccini BM, Tosti A. White superficial onychomycosis: epidemiological, clinical, and pathological study of 79 patients. Arch Dermatol 2004; 140:696.
- Szepietowski JC, Reich A, Garlowska E, et al. Factors influencing coexistence of toenail onychomycosis with tinea pedis and other dermatomycoses: a survey of 2761 patients. Arch Dermatol 2006; 142:1279.
- Sigurgeirsson B. Prognostic factors for cure following treatment of onychomycosis. J Eur Acad Dermatol Venereol 2010; 24:679.
- Finch J, Arenas R, Baran R. Fungal melanonychia. J Am Acad Dermatol 2012; 66:830.
- Lubeck DP, Gause D, Schein JR, et al. A health-related quality of life measure for use in patients with onychomycosis: a validation study. Qual Life Res 1999; 8:121.
- Elewski BE. The effect of toenail onychomycosis on patient quality of life. Int J Dermatol 1997; 36:754.
- Drake LA, Patrick DL, Fleckman P, et al. The impact of onychomycosis on quality of life: development of an international onychomycosis-specific questionnaire to measure patient quality of life. J Am Acad Dermatol 1999; 41:189.
- Roujeau JC, Sigurgeirsson B, Korting HC, et al. Chronic dermatomycoses of the foot as risk factors for acute bacterial cellulitis of the leg: a case-control study. Dermatology 2004; 209:301.
- Bristow IR, Spruce MC. Fungal foot infection, cellulitis and diabetes: a review. Diabet Med 2009; 26:548.
- Lawry MA, Haneke E, Strobeck K, et al. Methods for diagnosing onychomycosis: a comparative study and review of the literature. Arch Dermatol 2000; 136:1112.
- Lilly KK, Koshnick RL, Grill JP, et al. Cost-effectiveness of diagnostic tests for toenail onychomycosis: a repeated-measure, single-blinded, cross-sectional evaluation of 7 diagnostic tests. J Am Acad Dermatol 2006; 55:620.
- Wilsmann-Theis D, Sareika F, Bieber T, et al. New reasons for histopathological nail-clipping examination in the diagnosis of onychomycosis. J Eur Acad Dermatol Venereol 2011; 25:235.
- Jung MY, Shim JH, Lee JH, et al. Comparison of diagnostic methods for onychomycosis, and proposal of a diagnostic algorithm. Clin Exp Dermatol 2015; 40:479.
- Lim CS, Lim SL. New contrast stain for the rapid diagnosis of onychomycosis. Arch Dermatol 2011; 147:981.
- Shemer A, Davidovici B, Grunwald MH, et al. New criteria for the laboratory diagnosis of nondermatophyte moulds in onychomycosis. Br J Dermatol 2009; 160:37.
- Gupta AK. Treatment of dermatophyte toenail onychomycosis in the United States. A pharmacoeconomic analysis. J Am Podiatr Med Assoc 2002; 92:272.
- Elewski BE, Leyden J, Rinaldi MG, Atillasoy E. Office practice-based confirmation of onychomycosis: a US nationwide prospective survey. Arch Intern Med 2002; 162:2133.
- Litz CE, Cavagnolo RZ. Polymerase chain reaction in the diagnosis of onychomycosis: a large, single-institute study. Br J Dermatol 2010; 163:511.
- Gupta AK, Zaman M, Singh J. Diagnosis of Trichophyton rubrum from onychomycotic nail samples using polymerase chain reaction and calcofluor white microscopy. J Am Podiatr Med Assoc 2008; 98:224.
- Weinberg JM, Koestenblatt EK, Tutrone WD, et al. Comparison of diagnostic methods in the evaluation of onychomycosis. J Am Acad Dermatol 2003; 49:193.
- Tsunemi Y, Takehara K, Miura Y, et al. Screening for tinea unguium by Dermatophyte Test Strip. Br J Dermatol 2014; 170:328.
- Pharaon M, Gari-Toussaint M, Khemis A, et al. Diagnosis and treatment monitoring of toenail onychomycosis by reflectance confocal microscopy: prospective cohort study in 58 patients. J Am Acad Dermatol 2014; 71:56.
- Cinotti E, Perrot JL, Labeille B, Cambazard F. Reflectance confocal microscopy for cutaneous infections and infestations. J Eur Acad Dermatol Venereol 2016; 30:754.
- Nath AK, Udayashankar C. Congenital onychogryphosis: Leaning Tower nail. Dermatol Online J 2011; 17:9.