Decreasing prevalence of Microsporum canis infection in Korea: through analysis of 944 cases (1993-2009) and review of our previous data (1975-1992).

Since 1957, Microsporum (M.) canis has been one of the common causative agents of dermatophytosis in Korea. We analyzed 944 patients infected with M. canis who attended outpatient clinic over a 17-year period (1993-2009). M. canis infections were diagnosed by mycological examinations, including direct microscopic examinations with 15% KOH and cultures on potato dextrose agar complemented with 0.5% chloramphenicol. Mycological examinations confirmed 164,903 cases of dermatophytosis, 944 (0.6%) of which were M. canis infections. The annual prevalence of patients with M. canis infection was the highest in 2002 (91 cases). Then, the prevalence of patients with M. canis infection markedly decreased until 2008 (15 cases). The ratio of male to female patients was 0.65:1, but the ratio in children under the age of 15 was 1.14:1 and was 0.20:1 in adults. Seasonally, 274 cases occurred in winter, showing higher incidence than in other seasons. There was a difference in the clinical forms of M. canis infections between children and adults; tinea (T.) capitis was the most common form in children, but T. corporis was the most common in adults. We demonstrate that the decreasing prevalence of M. canis infections over the study period has been noted in Korea.