Encyclopedia of Ayurvedic Medicinal Plants

Kingdom:         Bacteria

Species:            M. leprae

       Mycobacterium leprae, also known as Hansen’s bacillus, is the bacterium that causes leprosy (Hansen's disease). It is an intracellular, pleomorphic, acid fast bacterium. M. leprae is a Gram-positive, aerobic rod-shaped (bacillus) surrounded by the characteristic waxy coating unique to mycobacteria. In size and shape, it closely resembles Mycobacterium tuberculosis. Due to its thick waxy coating, M. leprae stains with a carbol fuscin rather than with the traditional Gram stain. The culture takes several weeks to mature.

           Optical microscopy shows M. leprae in clumps, rounded masses, or in groups of bacilli side by side.

           It was discovered in 1873 by the Norwegian physician Gerhard Armauer Hansen, who was searching for the bacteria in the skin nodules of patients with leprosy. It was the first bacterium to be identified as causing disease in man.

          The organism has never been successfully grown on an artificial cell culture media.Instead it has been grown in mouse foot pads and more recently in nine-banded armadillos. This can be used as a diagnostic test for the presence of bacillus in body lesions of suspected leprosy patients.