[A long-term evolution on the epidemiological characteristics of leprosy, towards the goal of its elimination in 1949 - 2007 in China].

Objective: To understand the epidemiological characteristics of leprosy during the evolution of the disease, towards the goal of elimination for the past 50 years and longer, so as to provide experiences for accelerating eradication of leprosy in China.
Methods: Data were collected from National Surveillance System of Leprosy which was composed annually of all the data from county-based leprosy unit reporting system. All the data were reviewed retrospectively.
Results: A total number of 487 900 leprosy patients were reported from 1949 to 2007 in China. The case detection rate reduced from the highest of 5.56/100 000 in 1958 to the lowest of 0.12/100 000 in 2007. Leprosy patients mainly distributed in mountain areas in Yunnan, Guizhou, Sichuan, Guangdong Guangxi, Hunan and Jiangxi provinces with warm and damp climate and underdeveloped economy. After more than 50 years of leprosy control efforts, the case detection rate declined quickly in provinces in the eastern and the southern parts but very slowly in provinces in the western and the southwestern part of China. The ratio of relapsed patients to newly detected ones increased from 1:139 in 1960s' to 1:10 after 1980s', annually. The proportion of child cases among newly detected patients had been 3% - 4% since 1968. In the recent 20 years, the proportion of new patients with positive skin smear gradually increased and the rate of disability grade two reached 20% and more. The average age of new patients upon diagnosis was 45 years old in the east coastal provinces but only 38 years old in the southwest provinces. A new finding was that some new patients detected in the east coastal provinces were immigrants from the southwestern provinces.
Conclusion: With continuous socio-economic development and active efforts on leprosy control, the prevalence of leprosy gradually declined despite the long evolution period. Some negative events seemed to have influenced the trend of case detection.