Trichophyton tonsurans infection in Japan: epidemiology, clinical features, diagnosis and infection control.

In this review, we summarize the status of Trichophyton tonsurans infection in Japan in terms of epidemiology, clinical features, diagnosis and infection control. Since approximately 2000, outbreaks of T. tonsurans infections among combat sports club members have been reported frequently, with the infection then spreading to their friends and family members. The most common clinical features of T. tonsurans infection are tinea corporis, which is difficult to differentiate from eczema, and tinea capitis. Tinea capitis is classified as the seborrheic form, kerion celsi form or "black dot" form, although 90% or more of patients are asymptomatic carriers. The diagnosis of symptomatic T. tonsurans infection is established by potassium hydroxide examination and fungal culture. However, because there are many asymptomatic carriers of T. tonsurans infection, tests using the hairbrush culture method are necessary. An increase in asymptomatic carriers of T. tonsurans makes assessment of the current prevalence of the infection challenging and underscores the importance of educational efforts and public awareness campaigns to prevent T. tonsurans epidemics.