Leprosy Training Module for Medical Officers

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The Causative Organism – M. leprae
Leprosy is caused by Mycobacterium leprae, which was discovered
in 1873 by Hansen at Bergen in Norway. These Mycobacterium leprae
are pleomorphic, straight or slightly curved, rod – shaped gram positive
micro - organisms. They may appear like solid rods, fragmented or
granular. They are acid fast bacilli ( AFB ), because they are stained red
by a dye called carbol fuschin , and this red colour can not be removed
either by acid or alcohol. M. leprae is less acid fast than M. tuberculosis.
The presence of the bacilli can be demonstrated by taking skin
smears, and after staining with Zeihl Neilson stain , these bacilli can be seen
under microscope. They are seen lying singly, in clumps or in compact
masses known as globi. The living Leprosy bacilli appear as solid staining,
i.e., bright pink rods with rounded ends and uniformly stained through
their entire length. Although the discovery of Leprosy bacilli reported as early
as 1873, they could not yet be grown in artificial culture media. The generation
time of M. leprae in the mouse footpad is 12 – 14 days ( longest of any known
bacterium ). In comparison with this, the generation time of M. tuberculosis is
only 20 hours.
Leprosy
Patients
Skin Smear
Positive
Infective
Skin Smear
Negative
o n
Infective
As per GOI and WHO guidelines , skin smear examination has
now been stopped.
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