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.

Comparison of three methods for the extraction of mycobacterial DNA / 中华皮肤科杂志

Objective To compare three methods for the extraction of mycobacterial DNA.Methods Two commercial DNA extraction kits and an ordinary freeze-thawing method were used to extract DNA from the pure suspensions of three species of Mycobacteria (M.tuberculosis,M.leprae and M.smegmatis) at different densities (1 × 10 to 1 × 105 cells/ml),simulated clinical specimens containing different concentrations of mycobacterial cells (1 × 10 to 1 × 104 cells/ml).The purity and concentration of the extracted DNA were evaluated.Then,PCR was performed to amplify the 16S rRNA region of Mycobacteria.The performance of the three methods was compared by the purity and concentration of extracted DNA as well as the results of PCR.Further more,76 clinical skin specimens suspected to be infected with Mycobacteria were used to further validate the performance of these methods.Results All the extracted DNA samples could be detected by PCR.The highest purity of DNA was obtained by the kit A,followed sequentially by the freeze-thawing method and the kit B.When pure suspensions were used,the detection limit was consistently 1 × 102 cells/ml for all the three methods.With simulated specimens,the detection rate was consistently 100％ for all the three methods at the concentration of 1 × 103 cells/ml,60％ (12/20),55％ (11/20) and 55％ (11/20) for the kit A,kit B and freeze-thawing method respectively at the concentration of 1 × 102 cells/ml.The analysis of clinical specimens showed that the kit B could be used to extract DNA from paraffin-embedded specimens,with the detection rate similar to that of kit A and freeze-thawing method.Conclusions The kit A could rapidly yield high-quality genomic DNA of Mycobacteria by repeated cleaning of columns,and may serve as the optimal method for scientific and clinical studies,and the kit B is suitable for extracting mycobacterial DNA from fresh tissue specimens besides paraffin-embedded specimens.