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 population, shown in Table 1. Among them, 477 were new cases, with a new detection rate of 0.061/100,000 population. 65 leprosy cases recurred, with a recurrence rate of 0.008/100,000 population. The current leprosy cases in this area was 2372, with an annual prevalence rate of 0.305/100,000 population. Compared with 1998, the 2018’s annual new detection rate dropped from 0.078/100,000 population to 0.029/100,000 population, with a significant downtrend (χ2 =86.85,P<0.01). The annual recurrence rate dropped from 0.014/100,000 population in 1998 to 0.000/100,000 population in 2018, with a significant downward trend (χ2 =16.14, p < 0.01). The annual detection rate dropped from 0.092/100,000 population in 1998 to 0.029/100,000 population in 2018, with a significant downtrend (χ2=112.99, p < 0.01). The annual prevalence rate dropped from 0.309/100,000 population in 1998 to 0.134/100,000 population in 2018, with a significant downward trend (χ2=671.15, p < 0.01), shown in Table 1.
3.2 Population Distribution
3.2.1 Gender distribution
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 significant difference between sexes in case composition (χ2=304.17, p < 0.01), as shown in table 1.
3.2.2 Age distribution
Between 1998 and 2018, the average age of the new diagnosed leprosy patients in Shaanxi was 46.3 years old, and the average age of new diagnosed patients was postponed from 42.7 years old in 1998 to 49.2 years old in 2018, as shown in Table 1. During this period, 2 cases of 14-year-old children patients were detected (1: Ankang region, 2004; 1: Hanzhong region, 2007).
3.3 Regional distribution
542 new and recurrent cases belong to the local residents, and in 2018, 10 counties or districts in Shaanxi had newly diagnosed cases. Administrate regions in China are divided into four levels: province, region, county, and village. In Shaanxi province, there were 11 regions in 2018 (i.e. Xi’an region). 72 counties and 30 districts belong to these regions. County and district administrative levels are the same. By 2018, 28 counties or districts had existing cases, which mainly distributed in southern Shaanxi, including Hanzhong, Ankang, and Shangluo. Leprosy scattered in Guanzhong, and no cases were found in northern Shaanxi for many years (Fig 1). By the end of 2018, there is still one county (Yangxian county) in Shaanxi that has not reached the basic leprosy elimination index (1/100,000) stipulated by the Ministry of Health[14], China, and the prevalence rate of Yangxian county was 1.29/100,000 population.
3.4 Types of cases and disability
3.4.1 Case types
In 477 newly discovered cases, 399 cases (83.6%) were MB, and 78 cases (16.4%) were PB, shown in Table 2. The ratio of types was 5.12:1. No significant difference was found in the ratio of types between 1998 and 2018 (χ2=0.002, P>0.05). Statistical difference was found in the type ratio between the new detected and the recurrent cases (χ2=192.92, p < 0.01).
3.4.2 Disability
Of 477 newly diagnosed cases, 148 (31.03%) were grade 2 disability. The rate of disability increased from 10.71% in 1998 to 27.27% in 2018.
3.5 Delay diagnosis in new cases
The average delay period in diagnosis of 477 newly detected cases was 62.0 (43.8-112.4) months from the LEPMIS. However, the average delay period was shorter in 2018 than in 1998 (47.6 vs 64.0 months), shown in Table 2.