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

Department of Leprosy Control, Institute of Dermatology, Chinese Academy of Medical Sciences, Nanjing 210042, China.
Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi 12/2008; 29(11):1095-100.
Source: PubMed


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.
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.
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.
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.

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    • "Although leprosy patients are diagnosed throughout China, the majority of cases are found in pockets of endemicity in the ethnically diverse, mountainous, and underdeveloped southwest provinces of Yunnan, Guizhou, and Sichuan [8, 9]. The presentation of leprosy is extremely diverse, with patients exhibiting dichotomous immune responses, a wide range of bacterial burdens, and histopathological outcomes and most field programs lack the ability to thoroughly characterize the patients [10]. "
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    ABSTRACT: Leprosy is the disabling outcome of chronic infection with Mycobacterium leprae. The disease often evades early detection, particularly now that fewer clinicians are able to confidently diagnose the disease following the integration of leprosy control measures within general health services in many countries. Although leprosy is officially eliminated in China, endemic regions remain in some difficult-to-reach, underdeveloped areas in Southwest China. In order to better understand the extent of M. leprae infection and identify new leprosy cases in a timely manner, simple tools that can detect infection and the early disease are required. In this report we evaluated the performance of antigen-specific ELISA, the NDO-LID rapid diagnostic test, and antigen-specific whole blood assays (WBA) as potential diagnostic tools. Our data support the use of antibody detection tests and WBA to facilitate the diagnosis of multibacillary and paucibacillary leprosy, respectively. These tools could be invaluable for increased, but simplified, monitoring of individuals in order to provide referrals for clinical exam and early leprosy diagnosis.
    Full-text · Article · Aug 2014 · BioMed Research International
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    • "While, leprosy patients are still diagnosed nationwide, pockets of endemicity in the three ethnically diverse, mountainous and underdeveloped southwest provinces of Yunnan (YN), Guizhou (GZ) and Sichuan (SC) account for the major proportion of leprosy in China (Yu et al., 2010; Shen et al., 2008). In addition, migration of patients from highly endemic areas to other non-endemic areas with faster social-economic development prospects is ongoing (Shen et al., 2008). The case detection rates and delay in diagnosis are dependent on multiple factors such as age, occupation, nationality, endemicity, leprosy type and detection method (Chen et al., 2000; Shen et al., 2010, 2011). "
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    ABSTRACT: Leprosy continues to be detected at near stable rates in China even with established control programs, necessitating new knowledge and alternative methods to interrupt transmission. A molecular epidemiology investigation of 190 patients was undertaken to define M. leprae strain types and discern genetic relationships and clusters in endemic and non-endemic regions spanning seventeen provinces and two autonomous regions. The findings support multiple locus variable number of tandem repeat (VNTR) analysis as a useful tool in uncovering characteristic patterns across the multiethnic and divergent geographic landscape of China. Several scenarios of clustering of leprosy from township to provincial to regional levels were recognized, while recent occupational or remote migration showed geographical separation of certain strains. First, prior studies indicated that of the four major M. leprae subtypes defined by single nucleotide polymorphisms (SNPs), only type 3 was present in China, purportedly entering from Europe/West/Central Asia via the Silk Road. However, this study revealed VNTR linked strains that are of type 1 in Guangdong, Fujian and Guangxi in southern China. Second, a subset of VNTR distinguishable strains of type 3, co-exist in these provinces. Third, type 3 strains with rpoT VNTR allele of 4, detected in Japan and Korea were discovered in Jiangsu and Anhui in the east and in western Sichuan bordering Tibet. Fourth, considering the overall genetic diversity, strains of endemic counties of Qiubei, Yunnan; Xing Yi, Guizhou; and across Sichuan in southwest were related. However, closer inspection showed distinct local strains and clusters. Altogether, these insights, primarily derived from VNTR typing, reveal multiple and overlooked paths for spread of leprosy into, within and out of China and invoke attention to historic maritime routes in the South and East China Sea. More importantly, new concepts and approaches for prospective case finding and tracking of leprosy from county to national level have been introduced.
    Preview · Article · Jan 2013 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
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    ABSTRACT: To study the characteristics of leprosy transmission at low endemic situation and to analyze the reason why transmission still existed. A retrospective study was carried out on transmission of leprosy in thirteen leprosy high endemic villages in Wenshan district, Yunnan Province, China. A special questionnaire was designed for collecting the data. A total of 47 patients have been registered in 13 villages since 1991. Among them, 25 (53.2%) were leprosy household patients. The proportion of BI positivity was 57.4% (27). The average delay time from disease onset to diagnosis of leprosy was 12 +/- 7.9 months with a range of 1-36 months. The interval between 2 cases being detected in each village was in a range of 0.5 to 5.5 years. Many secondary patients occurred continuously after an 'index case' and they developed leprosy within the delay time of the disease of former patients. The authors here also reviewed some literature on chemoprophylaxis and discussed the importance. Most patients could not be detected at the early stage. It may be necessary of considering the chemoprophylaxis strategy among close contacts of leprosy to stop transmission in leprosy pocket areas.
    No preview · Article · Apr 2010 · Indian journal of leprosy
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