Estimates of the incidence and prevalence of dermatophyte infections vary.
Tinea capitis: most often caused by Trichophyton tonsurans and Microsporum canis. The peak incidence is between 3 and 7 years of age; black children are more likely to develop tinea capitis than white children.[2]Coloe JR, Diab M, Moennich J, et al. Tinea capitis among children in the Columbus area, Ohio, USA. Mycoses. 2010 Mar 1;53(2):158-62.
http://www.ncbi.nlm.nih.gov/pubmed/19302461?tool=bestpractice.com
[3]Abdel-Rahman SM, Farrand N, Schuenemann E, et al. The prevalence of infections with Trichophyton tonsurans in schoolchildren: the CAPITIS study. Pediatrics. 2010 May;125(5):966-73.
http://www.ncbi.nlm.nih.gov/pubmed/20403937?tool=bestpractice.com
Tinea pedis: the most common of the superficial fungal infections, occurring in up to 70% of adults.[4]Drake LA, Dinehart SM, Farmer ER, et al. Guidelines of care for superficial mycotic infections of the skin: tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. Guidelines/Outcomes Committee. American Academy of Dermatology. J Am Acad Dermatol. 1996 Feb;34(2 Pt 1):282-6.
http://www.ncbi.nlm.nih.gov/pubmed/8642094?tool=bestpractice.com
Tinea corporis: common, with highest prevalence in preadolescents in hot, humid climates.
Tinea cruris: most prevalent in adolescent and adult men.
Tinea barbae: uncommon and most likely to be found in men who have been in direct contact with infected farm animals.
Onychomycosis
The most prevalent condition affecting nails, accounting for approximately 50% of all nail disease.[5]Faergemann J, Baran R. Epidemiology, clinical presentation and diagnosis of onychomycosis. Br J Dermatol. 2003 Sep;149(suppl 65):1-4.
http://www.ncbi.nlm.nih.gov/pubmed/14510968?tool=bestpractice.com
Advancing age increases likelihood of developing fungal nail disease. One study reported 2% prevalence of onychomycosis in the pediatric-age population, increasing to 60% in those ages 80 years and over.[6]Gupta AK, Jain HC, Lynde CW, et al. Prevalence and epidemiology of unsuspected onychomycosis in patients visiting dermatologists' offices in Ontario, Canada - a multicenter survey of 2001 patients. Int J Dermatol. 1997 Oct;36(10):783-7.
http://www.ncbi.nlm.nih.gov/pubmed/9372358?tool=bestpractice.com
Other risk factors include diabetes, human immunodeficiency virus, immunosuppression, obesity, and smoking.[7]Gupta AK, Versteeg SG, Shear NH. Onychomycosis in the 21st century: an update on diagnosis, epidemiology, and treatment. J Cutan Med Surg. 2017 Nov/Dec;21(6):525-39.
http://www.ncbi.nlm.nih.gov/pubmed/28639462?tool=bestpractice.com
[8]Gupta AK, Daigle D, Foley KA. The prevalence of culture-confirmed toenail onychomycosis in at-risk patient populations. J Eur Acad Dermatol Venereol. 2015 Jun;29(6):1039-44.
http://www.ncbi.nlm.nih.gov/pubmed/25413984?tool=bestpractice.com