Isolations of dermatophyte from clinically normal scalps in M. canis infections using the hairbrush method.

The scalp hair of patients with dermatophytosis due to M. canis but without scalp lesions, and that of their family members without dermatophytosis were examined using the hairbrush method. The dermatophyte was detected in 93.8% of the scalps of those who lived in homes where cats were kept, and in 25% of those without cats. After the source of infection had been treated, the dermatophyte showed a gradually decreasing presence, finally disappearing altogether, so that no case of the disease on the scalp hair could be found. We inferred from the above findings in M. canis infections that, since the dermatophytes are seen in a high proportion of cases without scalp lesions, the dermatophytes, in many cases, exist only as saprophytes on the hair.