In our study, TC can affect individuals of any age, with cases reported as early as 41 days of life and as late as 80 years of age. Similar to other literature, the vast majority of cases of TC affect prepubescent children, with the average age reported between 3 and 7 years (39.15%)[5]. However, the prevalence in children under 3 years old is on the rise (from 19.67% during the period 1997–2010 to 32.49% during the period 2011–2020). In children, boys were more frequently infected with a boys/girls ratio of 1.5:1. However, in adult, TC prevalence in female is 9 times to male, which is higher than previous reports. There is a hypothesis that shorter hair of boys facilitates scalp contact with infectious fungi and makes hair loss and scaling of the scalp more noticeable, facilitating TC recognition in boys. In other hand, hormonal change might explain the higher susceptibility of TC in adult female, especially in postmenopausal women[6].
Dermatophytes causing TC can be classified by three main reservoirs preference: anthropophilic (humans) fungi, which include T. tonsurans, T. violaceum and T. rubrum; zoophilic (animals) fungi, which include M. canis and T. mentagrophytes complex; and geophilic (soil) fungi, which include N. gypseum. The predominant genus and species of causing pathogens often varies based on geographic location. For example, the prominent pathogen for TC is T. tonsuring in the United States, Northern and Western Europe, which is M. canis in Mediterranean Europe and China. But even in China, the specific species responsible for TC varies from each province[4, 6, 7]. Socioeconomic factors have been assumed to being related to spontaneous evolution in fungal distribution. So, zoophilic fungi M. canis is prominent in more developed region, like Guangzhou, Shanghai and Beijing, et al, with wages being higher and pets are more popular. That’s one of the reasons that the common source for TC in children are zoophilic dermatophytes. The main reservoirs of these organisms are mainly cats and dogs, but different mammalian species, like rabbits, also serve as endemic reservoir[7]. We found that M. canis was more associated with cats (61.9%) and dogs (50%), and Trichophyton spp. was more associated with rabbits. Moreover, in recent decade, T. mentagrophytes complex has replaced T. violaceum and now become the second prevalent organisms of TC. In adult, although M. canis is also the most common pathogen, the proportion of T. violaceum and T. rubrum was higher than that of children. Those are in consist with the results that tinea black dot is more prevalence in adult than in children[6, 8]. The high prevalence of anthropophilic species may suggest a human-to-human transmission pattern in adult TC. Some study stated that 60% of the TC patients had contact with persons having similar symptoms, and family members developed TC or tinea corporis or faciei due to the same agent in 45% of TC patients[9]. So, TC patients with other active infection sites and asymptomatic carriers are important contamination source and all family household members with lesions should be screened and treated accordingly[10].
With very rare to no exception, oral antifungal therapy is needed to eradicate TC. Previously, griseofulvin and itraconazole (ITZ) showed more efficacious for treating TC caused by Microsporum spp. And terbinafine (TRB) and ITZ showed equivalent efficiency for treating TC caused by Trichophyton spp[11]. In our study, we found that there is no significant difference in efficacy among using different oral anti-fungal therapeutics. These results are consistency of the RCT results which compared itraconazole with terbinafine for achieving complete cure in treating children infected with Trichophyton spp[11]. However, griseofulvin and fluconazole often necessitate a higher daily dose and a relatively longer treatment duration in order to achieve complete cure (clinical cure and mycological cure),that’s one of the main reason nowadays more physicians would choose TRB or ITZ for treating TC[5, 12]. Importantly, although the use of oral anti-fungal therapy in children was plagued by exaggerated worries of major side effects, side effects such as hepatotoxicity and hematological disturbances have proven to be very rare in both adults and children[5, 11]. Also, consideration of the specific causative organism according to selection of therapy, daily dose, and anticipated duration of treatment, incorporation of adjunctive topical antifungal therapy, and handling of fomites, which may promote transmission to others are significant aspects to address with parents of affected patients, more evidence needs to be demonstrated in further study.