Leprosy is a chronic infectious disease caused by Mycobacterium leprae, which essentially affects the peripheral nervous system but also involves the skin, eyes and sometimes certain other tissues. This disease is usually endemic in tropical countries, especially in developing countries. Historically in China, the endemicity of leprosy was much higher along the coast and in the Yangtze Valley. In 1950, the leprosy control program was initiated and organized by the Chinese Ministry of Health (MOH, now the National Health Commission), which implemented vertical programs from national to county levels. Repeated mass or general surveys were conducted in the 1950s, 1960s, and 1970s in most areas of the country to detect most of new and historical cases in the country for treatment with monotherapy of dapsone (1). The introduction of multidrug therapy (MDT) to leprosy programs in China in the mid-1980s resulted in a significant reduction in the prevalence of the disease.
Based on the definition of WHO for elimination of leprosy as a public health problem (a prevalence of less than 1 case per 100,000 residents), China had eliminated this disease at the national level in 1981 and at the provincial level in 1992 (1). Nonetheless, this disease continued to be disproportionally detected in some areas with 1.2% of counties or cities not having reached this WHO criteria as of 2010 and resulting in a significant proportion of their patients to be disabled. To address these issues, the MOH published a national leprosy-control plan (2011–2020) to specially aim at controlling leprosy and its harms through public health investment directly allocated for leprosy control (2). The program aims to improve along three axes: the total number of leprosy patients; the percentage of counties or cities with a prevalence lower than 1/100,000; and the proportion of newly detected cases with grade 2 disabilities (G2D).
The Leprosy Management Information System in China (LEPMIS) is an updated version of the original National Leprosy Recording and Reporting System (3) that was initiated in 1990 to collect individual data on all leprosy patients reported from all counties or cities in Mainland China for establishing a national computerized database. Data from the database are analyzed regularly by the National Center for Leprosy Control and reported at annual national leprosy meetings in China and shared with the WHO. Diagnosis of leprosy was based on clinical, bacteriological, and sometimes histopathological profiles. When calculating for prevalence, patients who were not clinically cured were considered clinically active, while case detection rate was defined as the number of newly detected cases divided by population. The newly detected patients with WHO grade 2 (visible) deformities or damages were defined as “disabled” for the calculation of the disability proportion and rate of new cases.
Data from LEPMIS indicated that both the prevalence or the case detection rate of leprosy significant declined between 2010 and 2018 to reach a national prevalence of 0.178 per 100,000 and detection rate of 0.037 per 100,000 residents in 2018 (Figure 1). The number of registered cases and new cases in 2018 decreased by 58.6% and 60.6%, respectively, from that in 2010 (4-5).
The registered cases declined from 5,479 in 2011 to 2,479 in 2018 and most cases were found in Yunnan, Sichuan, Guizhou, and Guangdong. A total number of 6,602 new cases were detected from 2011 to 2018, with an average annual decline of 11.0% compared with 1,324 in 2010 (Table 1). During 2011–2018, 4,254 (64.4%) cases occurred in priority provinces of Yunnan, Guizhou, Sichuan, and Guangdong.
Year Registered cases Prevalence rate (1/100,000) Newly detected cases Total Case detection rate (1/100,000) Male Children under 15 Mobile cases Cases with G2D Grade 2 disability rate (1/1,000,000) 2011 5,479 0.407 1,144 0.085 779 29 114 309 0.229 2012 5,071 0.375 1,206 0.089 847 29 103 346 0.256 2013 4,465 0.328 924 0.068 616 14 103 188 0.138 2014 3,961 0.290 823 0.060 560 14 109 165 0.121 2015 3,230 0.235 678 0.049 474 20 89 126 0.092 2016 2,925 0.212 672 0.049 457 19 93 148 0.107 2017 2,697 0.194 634 0.046 417 9 74 127 0.091 2018 2,479 0.178 521 0.037 329 7 71 99 0.071 Total 3,788† 0.276† 6,602 0.060† 4,479 141 756 1,508 0.137† Abbreviation: G2D=grade 2 disablity.
*The data from 2011 to 2015 were published in Chinese Journal of Dermatology in 2017, and in this study, the data were extended to 2011−2018.
† Average data.
Table 1. Epidemiological profiles of leprosy in China, 2011−2018*.
Among the newly detected cases in 2011–2018, male cases totaled 4,479 with a proportion of 67.8% and children under 15 cases totaled 141 with a proportion of 2.1%. Additionally, during this period, 11.5% of new cases were detected among people migrating from traditionally leprosy endemic areas to major cities such as Beijing, Shanghai, Guangzhou, and Shenzhen.
The number of newly detected cases with G2D was 1,508 cases during 2011–2018 and the proportion of new G2D cases had remained mostly at the level around 20.0%. The proportion of G2D slowly declined to 19.0% in 2018. The rate of new leprosy cases with G2D decrease from 0.222 per 1,000,000 residents in 2010 to 0.071 per 1,000,000 residents in 2008 at the population level. Eight cases with G2D were found among children during 2011–2018, giving a proportion of G2D of 5.7% (8/141). In 2018, one case with G2D was found among children giving a proportion of G2D among children cases of 14.3% (1/7).
There were 237 counties or cities with a prevalence rate above 1/100,000 by the end of 2010. After 8 years of implementing the leprosy program in China, by the end of 2018, there were still up to 75 counties or cities where the prevalence target of more than 1/100,000 was not achieved, accounting for 2.6% of the total number of counties or cities in the country (Table 2).
Indicator Target of National Program by 2020* Target of Global Strategy by 2020† Status by the end of 2018 at national level Reduction in the number of registered cases from that in 2010 > 50% NA 58.6% Proportion of newly diagnosed cases with grade-2 disability < 20% NA 19.0% Grade 2 disability rate at population NA < 1/1,000,000 0.071/1,000,000 Grade 2 disability rate among newly detected pediatric cases NA 0% 14.3% Proportion of counties or cities reaching the prevalence of less than 1/100,000 (N) > 98% (2,856) NA 97.4% (2,851) Abbreviation: NA=Not applicable.
* China National Program for Eliminating Harms Due to Leprosy (2010−2020).
† WHO Global Leprosy Strategy 2016−2020: Accelerating towards a leprosy-free world.
Table 2. Main targets proposed by China’s National Program and the WHO’s Global Strategy and status of these targets by 2018 in China.