Single nucleotide polymorphism-based molecular typing of M. leprae from multicase families of leprosy patients and their surroundings to understand the transmission of leprosy

Abstract

The exact mode of transmission of leprosy is not clearly understood; however, many studies have demonstrated active transmission of leprosy around a source case. Families of five active leprosy cases and their household contacts were chosen from a high endemic area in Purulia. Fifty-two soil samples were also collected from different areas of their houses. DNA was extracted from slit-skin smears (SSS) and soil samples and the Mycobacterium leprae-specific RLEP (129 bp) region was amplified using PCR. Molecular typing of M. leprae was performed for all RLEP PCR-positive samples by single nucleotide polymorphism (SNP) typing and confirmation by DNA sequencing. SSS of these five patients and six out of the total 28 contacts were PCR positive for RLEP whereas 17 soil samples out of 52 showed the presence of M. leprae DNA. SNP typing of M. leprae from all RLEP PCR-positive subjects (patients and smear-positive contacts) and 10 soil samples showed the SNP type 1 genotype. M. leprae DNA from the five leprosy patients and the six contacts was further subtyped and the D subtype was noted in all patients and contacts, except for one contact where the C subtype was identified. Typing followed by subtyping of M. leprae clearly revealed that either the contacts were infected by the patients or both patients and contacts had the same source of infection. It also revealed that the type of M. leprae in the soil in the inhabited areas where patients resided was also of the same type as that found in patients.

Genotyping of Mycobacterium leprae strains from a region of high endemic leprosy prevalence in India

“…In our previous studies, we found a diversity of M. leprae at eight SNP loci from clinical isolates obtained from leprosy patients or from multicase families residing mainly in Delhi and Purulia (West Bengal) regions. It was observed that SNP subtype 1D was the most predominant in the Indian population, SNP subtype 2E was noted only from the East Delhi region and SNP type 2 subtype G was noted only from the nearby areas of the Hoogly district of West Bengal (Lavania et al, 2013, Turankar et al, 2014. In this present study we got similar observations for SNP subtypes.…”

Presence of Mycobacterium leprae genotype 4 in environmental waters in Northeast Brazil

“…Thus, the predominance of SNP type 4 in Ceará is directly related to the Western African slaves. Similar to previous studies conducted in an endemic village in India, we found a concordance between the SNP subtyping (subtype 4-N) of M. leprae from skin biopsies and those from water samples 9,28 .…”

Detection ofMycobacterium lepraeDNA in soil; Multiple needles in the haystack?

“…Through PCR amplification of M. leprae DNA, its presence has been detected in environmental samples such as soil(11, 12) and water(13) in areas inhabited by leprosy patients in Brazil and India. The viability of M. leprae was assessed by its multiplication in footpads of wild type mice and showed that M. leprae can remain alive in wet soil for 46 days(14).…”