title: Viability of Mycobacterium leprae in the environment and its role in leprosy dissemination.
abstract: BACKGROUND
  Leprosy, a chronic disease caused by Mycobacterium leprae, is a public health concern in certain countries, including India. Although the prevalence of the disease has fallen drastically over time, new cases continue to occur at nearly the same rate in many regions. Several endemic pockets have been observed in India and elsewhere. The precise dynamics of leprosy transmission are still not clearly understood. Both live bacilli as well as M. leprae DNA have been detected in the soil and water of endemic areas; they possibly play an important role in disease transmission.
  
  
  OBJECTIVE
  To study the occurrence of viable M. leprae in environmental samples collected from areas of residence of patients with active leprosy.
  
  
  METHODS
  The study was conducted on 169 newly diagnosed leprosy patients in Ghatampur, Uttar Pradesh, India. Soil and water samples were collected from their areas of residence using a standardized protocol. An equal number of soil and water samples were also collected from non-patient areas of the same or adjoining villages. The environmental samples collected from the patients surroundings were subjected to 16S ribosomal RNA gene analysis after obtaining informed consent.
  
  
  RESULTS
  About a quarter of the environmental samples collected from patient areas, (25.4% of soil samples and 24.2% of water samples) were found to be positive for specific 16S ribosomal RNA genes of M. leprae. Environmental samples collected from non-patient areas were all found negative for M. leprae 16S ribosomal RNA genes.
  
  
  CONCLUSIONS
  The major limitation of the study was that the sample size was small.
  
  
  CONCLUSIONS
  The study demonstrated the presence of viable strains of M. leprae in skin smear samples of paucibacillary patients and multibacillary patients, as well as in the environmental samples obtained from around their houses. This could play an important role in the continued transmission of leprosy.
authors.affiliation: Department of Microbiology and Molecular Biology, National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra, India.
authors.forename: Partha Sarathi
authors.initials: PS
authors.lastname: Mohanty
authors.forename: Farah
authors.initials: F
authors.lastname: Naaz
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Katara
authors.forename: Lama
authors.initials: L
authors.lastname: Misba
authors.forename: Dilip
authors.initials: D
authors.lastname: Kumar
authors.forename: Deepak Kumar
authors.initials: DK
authors.lastname: Dwivedi
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Tiwari
authors.forename: Devendra Singh
authors.initials: DS
authors.lastname: Chauhan
authors.forename: Avi Kumar
authors.initials: AK
authors.lastname: Bansal
authors.forename: Srikanth Prasad
authors.initials: SP
authors.lastname: Tripathy
authors.forename: Kiran
authors.initials: K
authors.lastname: Katoch
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004269:DNA, Bacterial / Q000032:analysis; D018450:Disease Progression; D019353:Endemic Diseases / Q000706:statistics & numerical data; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007918:Leprosy / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D050296:Microbial Viability; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000235:genetics / Q000302:isolation & purification*; D011634:Public Health; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D018570:Risk Assessment; D012380:Role; D012494:Sampling Studies; D012988:Soil Microbiology; D014876:Water Pollution
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S