This study systemically reviewed all articles published in English and Chinese referring to TC in children younger than two years old. Overall, the data on TC in this age group are limited because of the unusual and low reported prevalence. Children aged 3 ~ 7 years old remain the most commonly affected[1]. We found that the epidemiology, pathogen spectrum and clinical presentation of TC in infants were similar to those in children older than 2 years old[50], and different from TC in adults[51]. In infants and children, boys were slightly more susceptible to TC than girls (1.28:1), which may be attributed to boys having short hair, more contact with animals and more outdoor physical activities[52]. We confirmed that the top four pathogens were M. canis, T. violaceum, T. mentagrophytes complex and T. tonsurans. The most common zoophilic species were M. canis, followed by T. mentagrophytes complex, which can cause dermatophytosis in animals, and indirectly infect humans through close contact[53]. The most commonly isolated anthropophilic dermatophytes were T. violaceum and T. tonsurans, and mothers were the main source of contagion, who acted as symptomatic or asymptomatic carriers of the anthropophilic pathogens. TC may be seen in various clinical presentation, including hair loss, scaling, black dots, follicular pustules and kerions, depending on the species of dermatophytes, the phase of infection and the immune status of the host[54]. The symptoms of TC in infants were similar to older children, and alopecic patches and scaling were noted as the most common types. Therefore, the diagnosis of TC should be considered when an infant presents with scaling, alopecic patches or broken hair on the scalp[23].
Historical data revealed that the fungal distribution pattern of TC in children, including infants, varied in different countries and times[55]. In China, with the development of economy, the improvement of sanitation and social changes, zoophilic fungi (M. canis) are gradually replacing anthropophilic fungi (T. schoenleinii and T. violaceum) as the most prevalent agent of TC[56]. In Central Europe and the Mediterranean countries, pets are becoming the most likely sources of contagion and TC is predominantly due to M.canis[57]. Whereas in the USA, France and the UK, due to the increase in the immigration of people with African origin, most cases of TC are caused by T. tonsurans[58, 59]. In some Africa areas, TC has always been a serious problem for the poor hygiene and socioeconomic conditions, and dermatophytes with partial geographical restriction, like T. violaceum and T. soudanense, were the leading pathogens[60, 61]. In our study, for the limited cases of TC in infants, we didn’t find the significant differences in fungal profiles across countries and regions.
Clinically, systemic antifungal drugs have always been recommended for the successful treatment of TC. Since 1959, griseofulvin remains the gold standard of systemic therapy for TC, but high doses and long treatment periods are warranted[62]. The newer antifungal agents terbinafine, itraconazole and fluconazole are now being used more frequently for TC especially in children older than 2 years old, with good efficacy and safety but a reduced treatment duration[6, 63]. However, for the majority of countries in the world, there are still no FDA approved oral agents or treatment guidelines of TC for the children less than 2 years of age[64]. Till now, there is controversy on whether systemic or topical treatment should be used for TC in infants. There are mainly two sides of cautious. For one hand, systemic therapy is an off-label treatment, and drug risks limit the use of oral drugs. For the other hand, although topical therapy is felt to be safer for infants, TC usually causes infection at the root of the hair follicle deep within the dermis, and topical treatment alone cannot completely clear the fungus, resulting in higher recurrence rates. In our literature review, we noted that both oral and topical drugs have achieved good therapeutic effects, and almost no reported side effects and recurrence were noted during the whole treatment period and follow up. Besides, Chen et al[65] found that oral itraconazole was safe and effective in infants and the profiles of adverse events were similar to those in adults and children through a retrospective analysis of a large number of articles. These results remind us oral antifungal drugs, including griseofulvin, itraconazole, terbinafine and fluconazole, have few adverse effects and topical treatment can be an alternative choice, furthermore, the issues of drug safety and recurrence are not as many as we worried about.
Here, we give the following treatment recommendation for infant TC according to these acquired data: (i) infants with consent of the guardian or severe clinical symptoms, treatment with systemic antifungal drugs should be recommended, and adverse reactions can be monitored; (ii) infants, especially neonates, with mild symptoms, underlying diseases or no agreement of their guardian, topical therapy should be considered; (iii) the combination of topical and systemic treatment for severe paitents might increase the cure rate and shorten the duration of systemic antifungal drugs; (vi) topical cream and antimycotic shampoo can be applied to reduce the transmission of infection and to decrease shedding of infected fungal elements[4].
In this study, we systematically summarized the epidemiological, clinical and pathogenic characteristics of TC in infants, and based on these data analysis, we gave the treatment recommendation. Oral treatment for TC in infants were safe, and topical therapy can be an alternative choice, achieving good therapeutic effects. In sum, it is of great significance to improve the treatment of TC in infants.