Onychomycosis in Hong Kong.

BACKGROUND: Onychomycosis in temperate countries has been studied extensively, but few data are available on its epidemiology in tropical countries. We performed a survey of patients seen in Hong Kong for the 8-year period from January 1987 to December 1994. METHODS: A retrospective study of the mycology laboratory records of patients attending the Government Dermatology Clinics was carried out. Nail samples examined included clippings, scrapings, and drillings. Microscopy was performed on all specimens. Sabouraud dextrose agar was used for culture. RESULTS: Out of a total of 2382 nail samples (1024 (43.0%) toe, 1148 (48.2%) finger, and 210 (8.8%) unspecified site) examined, 340 (14.3%) were microscopy positive; 165 (48.5%) of these were culture positive, including 160 (97%) with dermatophyte and/or yeast, and 5 (3%) with molds. Men were affected more in the < 19 and > 50 years age groups, whereas women were affected more in the 20-50 years age group. Women were affected significantly more than men with yeasts, dermatophytes occurred more during adolescence. Dermatophytes showed a high peak in late spring, although both dermatophyte and yeast cases peaked in the summer months. Dermatophytes (29.1%) occurred more commonly than yeasts (19.4%) in microscopy-positive onychomycosis cases in Hong Kong. Trichophyton rubrum was the commonest dermatophyte, and Candida spp, other than C. albicans, were the commonest yeasts. Mixed infections (5%) were uncommon. CONCLUSIONS: Dermatophytes are more important than yeasts as a cause of onychomycosis in Hong Kong. Changes in climatic conditions affect the prevalence of dermatophytes more than yeasts.