Monitoring and detection of leprosy patients in Southwest China: A retrospective study, 2010-2014.

More than 100 counties, mainly in southwest China, report incidence rates of leprosy >1/100,000. The current study analysed the epidemiology of leprosy in southwest China to improve our understanding of the transmission pattern and improve control programs. 207 counties were selected in southwest China. Leprosy patients and their household contacts were recruited. The data from the medical interview and the serological antileprosy antibody of the leprosy patients were analysed. A total of 2,353 new cases of leprosy were interviewed. The distribution of leprosy patients was partly associated with local natural and economic conditions, especially several pocket areas. A total of 53 from 6643 household contacts developed leprosy, and the incidence rate of leprosy in the household contacts was 364/100,000 person-years. We found that NDO-BSA attained higher positive rates than MMP-II and LID-1 regardless of clinical types, disability and infection time in leprosy patients. By means of combination of antigens, 88.4% patients of multibacillary leprosy were detected, in contrast to 59.9% in paucibacillary leprosy. Household contacts should be given close attention for the early diagnosis, disruption of disease transmission and precise control. Applications of serology for multi-antigens were recommended for effective coverage and monitoring in leprosy control.

Trends in case detection influenced by leprosy elimination campaigns in certain areas of China.

LECs were carried out from 1998 to 2000 in eight counties of west China. The number of cases detected during the year of LECs was much higher than that detected by routine methods before the year of the LEC. However, the annual number of cases detected during the year after the LEC showed different patterns. One pattern is that the number of new cases detected in the year after the LEC declined to the level similar to that before the year of the LEC. The second pattern is that the number of new cases detected in the year after the LEC declined steeply to less than that detected before the year of the LEC. Following peak case-detection during the year of the LEC, a gradual decrease in the number of new cases was observed in the subsequent years. The repeat LEC brought a weakly rebounding peak case-detection during the year following the first LEC carried out 3 years earlier. The operational, epidemiological and technical factors influencing the trends of case-detection during the LECs are discussed.

Analysis on the detection of new leprosy cases before, during and after the year of leprosy elimination campaigns.

To analyse the impact on of case finding of leprosy elimination campaigns (LECs), data on newly detected leprosy cases in a leprosy endemic area were collected before, during and after the year of LEC. The number of new leprosy cases detected during the year of LEC was significantly higher than previously. The number of newly detected cases after the year of LEC was similar to that of detected before the year of LEC in counties with persisting case finding activities. However, the number of newly detected cases after the year of LEC significantly decreased in counties without active case finding activities. The average distance from the homes of leprosy cases detected during LEC to the leprosy control unit at the count town was 62.8 km, which is farther than that of other leprosy cases detected before and after the year of LEC. The average time from disease onset to diagnosis of leprosy cases detected after the year of LEC shortened. The results also showed that carrying out LECs is unlikely to have a significant impact on the trend of case finding within a short time in local areas, but it may improve some indicators of leprosy patients and so promote leprosy control in local areas.