Epidemiological Scenario of Leprosy in a Province in China: Long Delay in Diagnosis and High Rate of Deformity. Ge Li Shaanxi Provincial Institute for Endemic Disease Control Qing-Ping Zhang Shaanxi Provincial Institute for Endemic Disease Control Zhao-Xing Lin Shaanxi Provincial Institute for Endemic Disease Control Ping Chen Shaanxi Provincial Institute for Endemic Disease Control Chao Li ( [email protected] ) Fourth Military Medical University https://orcid.org/0000-0002-6175-5701 Research article Keywords: Leprosy, Mycobacterium leprae, China, Epidemiology Posted Date: June 24th, 2020 DOI: https://doi.org/10.21203/rs.3.rs-34383/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Version of Record: A version of this preprint was published on November 25th, 2020. See the published version at https://doi.org/10.1186/s12889-020-09933-6. Page 1/11 Abstract Background: This ecological study aimed to analyze both the tendency and the characteristics of leprosy in an endemic province in the Chinese Northwest. Methods: The medical records of leprosy in the province of Shaanxi, China, 1998-2018 were collected from the leprosy management information system in China (LEPMIS). Epidemiological variables were analyzed in this study. Results: 477 new cases were diagnosed between 1998-2018 in this area. The average rate of annual detection was 0.070/100,000, and the average annual prevalence was 0.305/100,000. The mean age of new patients was 46.71 years, and the ratio of male to female was 2.46:1. There were 399 cases (83.6%) of multibacillary (MB) forms. 148 cases (31.03%) had grade II disability. The mean delay in diagnosis for new cases was 62.01 months. Conclusion: The epidemiological study showed that the characteristics of the new leprosy cases in our province were still long delay in diagnosis and high rate of deformity, which indicated the need of actions of stimulating early diagnosis and treatment, and strengthening the detection of leprosy in low prevalent areas. 1. Background Leprosy, which is caused by mycobacterium tuberculosis, is a chronic infectious disease, and it mainly induces injuries of skin and peripheral nerves. In China, the epidemic of leprosy has a history of more than 2,000 years, and there is no effective vaccine by now[1]. The long course, high deformity rate, and other medical problems may cause a series of social problems, such as low quality of life and low happiness index caused by discrimination[2]. Since the founding of the People’s Republic of China in 1949, our government has carried out a great deal of public health work and taken a large number of effective measures of prevention and control. By 2018, the incidence rate of leprosy in Shaanxi province, China had been kept below 1/100,000 and basically eliminated. However, there are still sporadic new cases. As an important part of the Silk Road Economic Belt and the 21st-Century Maritime Silk Road (B&R), our province covers a total area of 205,800 square kilometers and has a resident population of 38.64 million (December, 2018). Due to different regional and population distribution, in order to explore the epidemic trend and characteristics of leprosy in this province, we retrospectively reviewed the leprosy cases between 1998 to 2018, and tried to provided basis for effective prevention and control of leprosy in low epidemic situation. 2. Methods 2.1 The diagnosis standard Page 2/11 The diagnoses of new and recurrent leprosy were based on Leprosy Prevention Manual for Primary Care Physicians (PCPs) and Leprosy Diagnosis Standard WS291-2008. Cases were classied according to the Leprosy Classication Standard, WHO, 1987. Disability classication was bases on the Disability Classication Standard for Leprosy, WHO, 1988. 2.2 Data sources All new and recurrent leprosy cases were collected from the Leprosy Prevention and Control Management Information System in China (LEPMIS). Population data came from the Shaanxi Statistical Yearbook. 2.3 Statistical analysis A new and recurrent leprosy cases database was established in EXCEL 2010. U test, χ2 test, and t test were used for statistical analysis when appropriate in SPSS Statistics 19.0 (IBM Corp., Armonk, NY, USA). 3 Results 3.1 The overall situation and changing trend Between 1998 and 2018, 542 leprosy cases were found in Shaanxi province, with an annual rate of detection of 0.070/100,000, shown in Table 1. Among them, 477 were new cases, with a new detection rate of 0.061/100,000. 65 leprosy cases recurred, with a recurrence rate of 0.008/100,000. The current leprosy cases in this area was 2372, with an annual prevalence rate of 0.305/100,000. Compared with 1998, the 2018’s annual new detection rate dropped from 0.078/100,000 to 0.029/100,000, with a signicant downtrend (χ2 = 86.85,P0.01). The annual recurrence rate dropped from 0.014/100,000 in 1998 to 0.000/100,000 in 2018, with a signicant downward trend (χ2 = 16.14, p < 0.01). The annual detection rate dropped from 0.092/100,000 in 1998 to 0.029/100,000 in 2018, with a signicant downtrend (χ2 = 112.99, p < 0.01). The annual prevalence rate dropped from 0.309/100,000 in 1998 to 0.134/100,000 in 2018, with a signicant downward trend (χ2 = 671.15, p < 0.01), shown in Table 1. Page 3/11 Table 1 The detection and prevalence in Shaanxi province from 1998 to 2018. Year New New Relapse Relapse Detect Annual Existing Morbidity cases detection cases rate cases detection cases rate rate (1/106) (1/106) (1/106) (1/106) 1998 28 0.078 5 0.014 33 0.092 111 0.309 1999 11 0.030 4 0.011 15 0.042 96 0.265 2000 34 0.094 1 0.003 35 0.097 115 0.319 2001 42 0.117 4 0.011 46 0.128 143 0.398 2002 31 0.086 2 0.006 33 0.092 152 0.423 2003 21 0.058 2 0.006 23 0.064 150 0.417 2004 24 0.067 7 0.019 31 0.086 161 0.447 2005 35 0.095 6 0.016 41 0.112 170 0.463 2006 40 0.107 7 0.019 47 0.126 162 0.433 2007 39 0.104 7 0.019 46 0.123 170 0.453 2008 16 0.043 4 0.011 20 0.053 157 0.418 2009 20 0.053 6 0.016 26 0.069 129 0.341 2010 21 0.056 2 0.005 23 0.061 102 0.270 2011 24 0.064 2 0.005 26 0.070 106 0.284 2012 16 0.041 0 0.000 16 0.041 86 0.221 2013 10 0.027 1 0.003 11 0.029 69 0.184 2014 13 0.035 1 0.003 14 0.037 64 0.171 2015 12 0.032 2 0.005 14 0.037 59 0.152 2016 14 0.038 1 0.003 15 0.041 61 0.167 2017 15 0.041 1 0.003 16 0.044 57 0.156 2018 11 0.029 0 0.000 11 0.029 52 0.134 Total 477 0.061 65 0.008 542 0.070 2372 0.305 3.2 Population Distribution 3.2.1 Gender distribution Page 4/11 Among 477 newly diagnosed leprosy patients, 339 were males and 138 were females, with a male-to female ratio of 2.46:1, with a signicant difference between sexes in case composition (χ2 = 304.17, p < 0.01), as shown in Table 2. Page 5/11 Table 2 The ratios of types, sexes, and II disability in new cases between 1998 and 2018. Year New detected cases Cases MB PB Type Male Female Sex Cases with Rate of II ratio (n%) ratio II disablity disability (n%) (M/F) 1998 28 25 3 89.29 19 9 2.11 3 10.71 1999 11 10 1 90.91 8 3 2.67 2 18.18 2000 34 30 4 88.24 22 12 1.83 7 20.59 2001 42 38 4 90.48 26 16 1.63 22 52.38 2002 31 25 6 80.65 26 5 5.20 6 19.35 2003 21 17 4 80.95 18 3 6.00 4 19.05 2004 24 23 1 95.83 17 7 2.43 6 25.00 2005 35 26 9 74.29 27 8 3.38 11 31.43 2006 40 30 10 75.00 26 14 1.86 15 37.50 2007 39 31 8 79.49 30 9 3.33 14 35.90 2008 16 12 4 75.00 12 4 3.00 3 18.75 2009 20 19 1 95.00 15 5 3.00 11 55.00 2010 21 16 5 76.19 14 7 2.00 4 19.05 2011 24 20 4 83.33 15 9 1.67 7 29.17 2012 16 14 2 87.50 10 6 1.67 5 31.25 2013 10 8 2 80.00 7 3 2.33 4 40.00 2014 13 11 2 84.62 10 3 3.33 6 46.15 2015 12 11 1 91.67 9 3 3.00 4 33.33 2016 14 9 5 64.29 11 3 3.67 8 57.14 2017 15 14 1 93.33 10 5 2.00 3 20.00 2018 11 10 1 90.91 7 4 1.75 3 27.27 Total 477 399 78 83.65 339 138 2.46 148 31.03 3.2.2 Age distribution Page 6/11 Between 1988 and 2018, the average age of the new diagnosed leprosy patients in Shaanxi was 45.21 years old, and the median age was postponed from 42 in 1998 to 51 in 2018, as shown in Table 3.