Single nucleotide polymorphism (SNP) based molecular typing of M.leprae from multi-case families of leprosy patients and their surroundings to understand the transmission of leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. It is one of the oldest recorded diseases of mankind. The changes in the registry pattern after the implementation of MDT in the vertical program has drastically brought down the prevalence (PR) whereas the incidence has not come down at many places of the world [1] including India [2] wherein the prevalence of <1/10,000 has been attained. A total of 11 districts with incidence rate > 50/100,000 population still exist in Chhattisgarh, Gujarat, Maharashtra, West Bengal, Dadra & Nagar Haveli, Orissa and Delhi [2]. The global use of MDT seems to have had only minimal, if any, effect on transmission of the disease [3] and an adequate explanation for this situation is lacking. Multibacillary (MB) leprosy patients harbor enormous number of leprosy bacilli and discharge them freely from their skin, nasal ulcers and saliva [4, 5].