Detection of Mycobacterium leprae DNA from soil samples by PCR targeting RLEP sequences

Despite near elimination of leprosy as a public health problem, several problems in leprosy still remain. These include early detection, determining efficacy of the treatment and differentiating relapses from re-infection. These aspects have important impact on the patients undergoing treatment and also have a bearing on understanding transmission dynamics in the community. While early diagnosis and management do not need major technological inputs, various reports have suggested that M. leprae is found in the environment and may have a role in continued transmission of disease. In earlier studies from other parts of world the presence of M. leprae DNA in the environment has been investigated both by microbiological and molecular studies. In the present study, an attempt was made to extract M. leprae DNA from soil samples, which were collected from eighteen different locations including 3 from our Institute area and 15 from different villages of Ghatampur area. We optimized a protocol for the extraction of DNA and amplified a fragment of M. leprae using specific primers targeting RLEP sequences. It was found that 33.3% of these soil samples collected from areas inhabited by leprosy cases gave positive result for M. leprae specific DNA. The utility of this method needs to be explored on a larger scale to establish the presence of M.leprae in the environment, and its role in the spread of the disease.