Epidemiology of leprosy and response to treatment in Hong Kong.

OBJECTIVES: To review the reported trend of leprosy in Hong Kong.

DESIGN: Retrospective study.

SETTING: Three major leprosy clinics in Hong Kong.

PATIENTS: Leprosy patients registered between 1970 and 2004.

MAIN OUTCOME MEASURES: Incidence, rate of deformities, distribution of leprosy subtypes, age distribution, and relapses after therapy.

RESULTS: The incidence of leprosy has decreased from 3.2 per 100,000 population in 1970 to 0.088 per 100,000 population in 2004. The proportion of the three subtypes of leprosy has remained roughly equal. There have been 87 relapses within this period with 54 (62%) cases of lepromatous leprosy, 22 (25%) borderline leprosy, and 11 (13%) tuberculoid leprosy. The overall relapse rate was 6.7% (0.2 per 100 person-years); this can be subdivided as a relapse rate for multidrug therapy of 3.2% (0.33 per 100 person-years) and for dapsone monotherapy of 8.3% (0.2 per 100 person-years). The mean interval to relapse for multidrug therapy and dapsone monotherapy was 1.83 and 5.8 years, respectively. The mean duration till relapse for patients on dapsone monotherapy was 15.6 years.

CONCLUSION: Treatment with recommended WHO-multidrug therapy is effective and well tolerated. Dapsone monotherapy is no longer effective. Leprosy is well controlled in Hong Kong but continued surveillance is required to detect relapses and to ensure good patient compliance with treatment.