Changes in frequency of agents of tinea capitis in school children from Western China suggest slow migration rates in dermatophytes

Abstract

Tinea capitis is a common dermatophyte infection of the scalp of children in Western China, with the gray-patch from being the most prevalent. Twenty years ago, the most widespread etiologic agent was reported to be Trichophyton violaceum, which was later succeeded by Microsporum ferrugineum and Trichophyton schoenleinii. In the framework of our recent study, 97 isolates were collected from patients with clinically suspected tinea capitis. Identification was performed by conventional methods and by sequencing the ribosomal DNA internal transcribed spacer region. In the case of T. violaceum an additional microsatellite primer set (T1) was used. Five species (in order of frequency, Trichophyton violaceum, T. schoenleinii, Microsporum ferrugineum, zoophilic strains of Arthroderma vanbreuseghemii, and Trichophyton tonsurans) were identified. Results of molecular and phenotypic ID of the same strains showed good correspondence. Comparison with earlier data showed that dermatophytes species in former rural societies must have migrated extremely slowly. Preponderance of local transmission from domesticated animals was proven by the occurrence of zoophilic strains of Arthroderma vanbreuseghemii. Etiologic agents in the rural communities of Western China tend to be different from those of the other regions in the country, despite modern communication and traffic.