Mycobacterium leprae and leprosy: A compendium

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, whi ch was discovered by G.H.A. Hansen in 1873. M. leprae is an exceptional bac terium because of its long generation time and no growth in artificial medi a. Entire sequencing of the bacterial genome revealed numerous pseudogenes (inactive reading frames with functional counterparts in M. tuberculosis) w hich might be responsible for the very limited metabolic activity of M. lep rae. The clinical demonstration of the disease is determined by the quality of host immune response. Th1-type immune response helps to kill the bacter ia, but hosts are encroached upon when Th2-type response Is predominant. Th e bacteria have affinity to the peripheral nerves and are likely to cause n europathy. AL leprae/laminin-alpha2 complexes bind to alpha/beta dystroglyc an complexes expressed on the Schwann cell surface. WHO recommends a chemot herapy protocol [multidrug therapy (MDT)] which effectively controls the di sease and contributes to the global elimination program. Leprosy has been s tigmatized throughout history, and recent topics regarding the disease in J apan are also discussed.