Abstract :
[en] Objectives: Tinea capitis (TC) is a superficial infection of the scalp caused by dermatophyte fungi which affects mainly prepubescent children. This last decade, a huge increase of African anthropophilic strains causing tinea capitis, has been observed in Europe, probably due to immigration waves from African countries. The Belgian National Reference Center for Mycosis (NRC) has conducted a surveillance study about TC in 2018. This work presents final results of the study for the epidemiological part and preliminary results for the molecular part. Methods: Belgian laboratories were invited to send all dermatophytes strains isolated from the scalp from January to December 2018. Dermatologists were involved and were asked to fill a form containing several epidemiological information about the patient. Strains identification was confirmed by ITS sequencing. A multiplex pan-dermatophyte real time PCR assay (DermaGenius®, PathoNostics) was applied if necessary. Typing of the M.audouinii strains was done using rep-PCR method (Diversilab, BioMérieux). Results: A total of 337 strains have been collected from 337 patients. The main population concerned by TC was children from 5-9 years (165/337, 49,01%). Males (214/337, 63,5%) were more affected than females (123/337, 36,5%), the sex ratio M/F was of 1,74. The majority of the strains was collected in Brussels area (181/337, 53,8%), followed by Liege area (73/337; 21,7%). Other Belgian cities were less concerned by TC. Among known ethnical origins (n=119), African people (114/119, 96,2%) were more concerned by TC than European people (5/119, 3,8%), (p<0,0001). The majority of patients were from Guinea (26/119, 21,8%), followed by Cameroun (14/119, 11,8%) and RDC (14/119, 11,8%), many other African nationalities were represented (12 different countries, all over Africa). The main transmission mode of TC was the familial way (83,3% among known cases n=126, 105/126). The major etiological agent was Microsporum audouinii (118/337, 35%) followed by Trichophyton soudanense (83/337, 24,6%), T. tonsurans (27/337, 17%), M. canis (36/337, 10,7%), T. violaceum (28/337, 8,3%), T. benhamiae (7/337, 2,1%), T. mentagrophytes (5/337, 1,48%) and M. incurvatum (1/337, 0,3%). This last rare dermatophyte has never been reported as responsible for TC in Belgium before. M. audouinii strains have been genotyped by rep-PCR and three genotypic variants have been characterized, one of them circulating mainly in Brussels area. No link with a particular ethnical origin could be found among genotypic groups. Conclusion: African anthropophilic dermatophytes such as M.audouinii and T. soudanense are mainly responsible for tinea capitis in Belgium. Large cosmopolitan cities like Brussels and Liege are the most concerned. People from African origin are mostly affected by TC. Among the M. audouinii strains circulating in Belgium, a genotypic diversity has been characterized.
