Abstract: Objective To investigate the cause of an outbreak of tinea capitis in a primary school.Methods All of the exposed children were surveyed by physical examinations and mycological examinations,including KOH preparation and fungal culture.The environment was also investigated in the school.With molecular typing of M.canis isolated from the patients and the environment,random primer amplification polymorphic DNA(RAPD) method,specific amplification of subrepeat elements in ribosomal DNA nontranscribed spacer(NTS),and DNA sequencing in intertranscribed spacer(ITS) of rDNA were performed.Results The total number of exposed children was seventy-one,among which fourty-two were suffered from tinea capitis.The ratio between boys and girls was 13:1.The age of the patients ranged from 3.5-10 years old.Four patients bred cats or dogs as pets.Fourty-one patients had noninflammatory type of tinea capitis and one had inflammatory type.Under microscopy all affected hairs showed ectothrix infection.M.canis was isolated from the patients,as well as from carpets in gymnasium and pillowcases in the school.The patterns of all strains of M.canis were identical in both RAPD and PCR amplification of rDNA NTS region.The same DNA sequence was found in the ITS region of isolates from the patients and the environment.Conclusion The outbreak of tinea capitis was caused by M.canis.M.canis strains isolated from the patients and from the environment were probably the same origin.

Key words: Outbreak, Epidemiology,molecular, Disease outbreaks, Tinea capitis