Download Leprosy

Matthew Lanning
Dr. Gallo
Take-home #1
Leprosy is a prevalent disease causing a large variety of dermatological and respiratory
conditions and frequently leads to secondary infections resulting in things such as extremity loss.
Leprosy has been affecting humans for most of recorded history. The oldest documented case is
from 4,000 years ago, found by analyzing the DNA of a man buried in a tomb in
Jerusalem.(Hamilton, 2000) The causative agent is Mycobacterium leprae. Its name comes from
the Greek lepi which means scale like. Said agent was discovered in 1873 by Norwegian
physician Gerhard Armauer Hansen.(Kupper, na) The prior historical event led to the ability to
identify and cure most affected patients and thus changed the certain death and exile experienced
by its victims.
To understand the historical and contemporary significance of Hansen’s find, some things
about the bacteria in question must be known first. Mycobacterium leprae belongs to a class of
bacteria with a very unique cell membrane structure. Beneath the normal outer lipids lies a layer
composed of mycolic fatty acids which are difficult to penetrate for both stains for classification
and other chemicals.(McMurray, 1996) For example, some antibiotics are unable to penetrate the
bacterium’s membrane making them very difficult to treat. Interestingly enough, the genus
Myobacterium also encompasses tuberculosis and other commonly endemic diseases. In addition
to the treatment difficulties, the additional layer prevents dehydration, thus creating a very
resilient bacterium. M. leprae is an aerobic bacilli that has one of the longest division times for
any known bacteria (aprox. 12-20 days). It is rarely found free living, defining it as an obligate
parasite. The only successful cultures in a laboratory setting were done by injecting M. leprae
into the foot pads of mice or the less frequent injection into an armadillo.(McMurray, 1996;
Solncezewski, 2009)
As previously stated, treatment for this unique bacteria is difficult. Not only is it
extremely resilient, but it quickly becomes resistant to antibiotics that do affect it. If that was not
bad enough, it has a potential incubating period of somewhere between three and five
years.(Solncezewski, 2009) That is enough time to allow that infected person to leave an area
they were perhaps just visiting, and move to another allowing the parasite to move into an
entirely new population. The symptoms of leprosy make this even easier. Identified by the
combination of things such as a runny nose, reddish skin, dry eyes or scalp and loss of sensation
in fingers and toes, leprosy could easily be mistaken as a simple cold or a neurological disorder
both of which would not warrant sufficient protective protocol.( Solncezewski, 2009) However,
much thanks to Hansen’s identification, doctor’s offices and laboratories can easily identify a
sample of M. leprae. After finding this new pathogen, Hansen sent his data and a sample to his
fellow scientist (and soon fierce competitor) Albert Neisser. Neisser successfully stained the
bacteria off of the tissue samples. Their conjoined finding allowed for a way to recognize M.
leprae and possibly prevent it from spreading further. In 1940, it was determined that M. leprae
was sensitive to dapsone or diaminodiphenylsulfone. Quickly immunity was developed to this
antibiotic – possibly due to its remarkably small genome. In more recent times, MDT—multidrug treatment—has been developed. (Kupper, na) When combined with rifampicin and
clofazimine (the components of MDT), dapsone appears to regain its effectiveness. However,
once the bacterium has been eradicated from the victim, the symptoms still
persist.(Solncezewski, 2009)
The significance of Hansen’s and Neisse’s findings is unfathomable. At one point leprosy
was a disease of biblical proportions and now it has been reduced primarily to India and a few
locations in Africa, these both a result of poor medical care. In addition to its medical
significance, the discovery of the genus of bacteria Mycobacterium has changed the way
microbiologist look at things under the microscope. Their world has been broadened by these
new means of differentiation and has been challenged to culture the un-cultureable. In fact, it
could be said that because of their identification, a whole new perspective on the microbial world
was developed.
Works Cited
Kupper, Patirck J. "Gerhard Henrik Armauer Hansen." Whonamedit -. N.p., n.d. Web. 13 Sept. 2013.
McMurray, David N. "Mycobacteria and Noradia." Mycobacteria and Nocardia. U.S. National Library
of Medicine, 17 Jan. 0096. Web. 11 Sept. 2013.
Slonczewski, Joan. "Host Dependency of Mycobacterium Leprae." - MicrobeWiki. Kenyon College,
2009. Web. 11 Sept. 2013.
Hamilton, Bernard (2000). The leper king and his heirs: Baldwin IV and the Crusader Kingdom of
Jerusalem. Cambridge, UK: Cambridge University Press. ISBN 0-521-64187-X.