introduction, characteristics, epidemiology, pathogenesis, mode of transmission, clinical sign and symptoms, lab diagnosis, preventive measure and treatment of Mycobacterium leprey

1. Mycobacterium
leprey
Prepared By:
Anish Lamichhnae
Bachelor of Public Health (BPH)
First Year (1st Semester)
CIST College

2. Scientific Classification
Domain : Bacteria
Phylum : Actinobacteria
Class : Actinobacteria
Order : Actinomycetales
Sub-order : Corynebacterineae
Family : Mycobacteriaceae
Genus : Mycobacterium
Species : leprae

3. Introduction
• Mycobacterium leprae, also called Hansen’s
bacillus spirilly is found in warm tropical
countries.
• It is a gram-positive bacterium that causes
leprosy (Hansen’s disease).
• M. leprae is an rod-shaped bacterium
surrounded by the waxy coating unique to
mycobacterium.
• It is an intracellular, pleomorphic, pathogenic
bacterium.
• In size and shape, it closely resembles
Mycobacterium tuberculosis.

4. Bacterial Morphology
• Optical microscopy shows M. leprae in clumps,
rounded masses, or in groups of bacilli side by side.
• The bacilli are slender, slightly curved or straight
rods, 1-8μm in length and0.2-0.5μm in diameter.
• The bacilli are acid-fast but less than the tubercle
bacilli and for which 5% sulphuric acid is used for
decolourization after staining with steamed carbol
fuchsin. They aren’t alcohol-fast.
• It has the longest doubling time of all known bacteria
and has thwarted every effort at culture in the
laboratory.

6. Cultivation
• The organism has never been successfully grown on
an artificial cell culture medium. Instead, it has been
grown in mouse foot pads and more recently in nine-
banded armadillos because they like humans, are
susceptible to leprosy.
• The difficulty in culturing the organism appears to be
because it is an obligatory intracellular parasite that
lacks many necessary genes for independent survival.
• Also the complex and unique cell wall that makes
members of the Mycobacterium genus difficult to
destroy is apparently also the reason for extremely
slow replication rate.
• The generation time from animal experiments is
found to be 12-13days on the average.

8. Epidemiology
• Mycobacterium leprae is thought to have originated
in East Africa and spread across the globe through
human migratory trends, reaching the Western
world within the last 500 years.
• In 2012, the World Health Organization recorded a
prevalence of approximately 180,000 cases.
• Through eradication efforts, the total number of
cases worldwide has decreased, yet the number of
new cases each year has remained consistent.
• Mortality is difficult to measure with leprosy, as the
infection is not the immediate cause of death in
many cases.

9. Pathogenesis

16. Control & Prevention
Control:
So far there hasn’t been any live attenuated
vaccine preparation for leprosy, but BCG vaccine
appears to give some protection against leprosy.
Prevention:
Preventive measure for M. leprae is to avoid close
contact with infectious people who are untreated.
Armadillos are also known hosts for
Mycobacterium leprae and have infected humans
in the southeastern United States, although the
geographic range of the disease and its
complexity has been spreading.

17. Treatment
oWHO recommended multidrug therapy
(MDT) for all leprosy cases based on
dapsone, rifampicin and clofazimine.
oDapsome has been successfully used for
over 50 years, but now the bacteria are
becoming resistant to the treatment.
oNow they have started using multidrug
therapy of Rifampicin, Clofazamine, and
Dapsome

20. References
https://www.slideshare.net/doctorrao/mycobact
erium-lepra-13169117
https://www.slideshare.net/GovindSah/mycoba
cterium-leprae-33591998
https://www.slideshare.net/swethapanneer/stru
cture-of-mycobacterium-leprae
https://en.wikipedia.org/wiki/Mycobacterium_
leprae
A textbook of microbiology- P. Chakraborty