Epidemiological survey of 42 403 dermatophytosis cases examined at Nagasaki University Hospital from 1966 to 2015

The causative species of a total of 42 403 dermatophytosis cases that occurred during 1966–2015 were surveyed. The most prevalent clinical type was tinea pedis, followed by tinea unguium, corporis, cruris, manus, faciei and capitis. The prevalence of tinea faciei and capitis has increased since the late 1990s and the late 2000s, respectively. The most prevalent dermatophyte species was Trichophyton rubrum, followed by Trichophyton mentagrophytes (the majority of the isolates were Trichophyton interdigitale in the latest nomenclature). These dermatophytes were detected in over 80% of the isolates identified in tinea pedis, unguium, cruris and manus cases. Recently, Microsporum canis and Trichophyton tonsurans have been increasingly identified. The frequency of M. canis isolated from tinea corporis, faciei and capitis cases started to rise in the early 1990s. T. tonsurans was first identified in Nagasaki in 2003. T. rubrum was the most commonly isolated pathogen in tinea faciei and corporis cases. However, the proportion of cases attributed to it has decreased since the early 1990s, whereas M. canis and T. tonsurans are being increasingly isolated since the early 2000s. In tinea capitis cases, the proportion of each pathogen isolated has changed dramatically. M. canis was first identified in the late 1970s, with an increasing prevalence up to the early 1990s. In contrast, the prevalence of T. tonsurans has increased since the early 2000s. In the 2010s, the most common fungus causing tinea capitis was T. tonsurans, followed by M. canis and T. rubrum.