Serendip is an independent site partnering with faculty at multiple colleges and universities around the world. Happy exploring!

Disease of the "Ancients" Still in Force

Jen's picture



                  When one first hears the word “leprosy”, Biblical images of stumbling, impoverished figures of society may come to mind, even though we now know that the disease as recorded in the Bible was a skin condition improperly translated as leprosy (in the Bible, this disease is tzaraath). However, what the Bible can tell us is that sufferers of leprosy and similar conditions  were considered to be under a punishment from God and were therefore shunned from society. This social stigma extended beyond Hebrew culture, however; for example, in Greek society, lepers were forced to live in secluded colonies so as to avoid spreading the disease to healthy people. Today, many people still leave their loved ones alone and in poverty if they contract leprosy (4). I decided to research this disease because I, like many ignorant others of the modern world, wanted to know what had become of this disease and whether it still existed. And it does. Today, we know leprosy as Hansen’s disease, named after G.A. Hansen, a Norwegian physician who is credited with discovering the cause of the disease in 1873.

The cause of Hansen’s is the rod shaped bacterium Mycobacterium leprae, transmitted through either skin contact or through respiration; the method is still under much dispute, though it is presumed that some sort of contact needs to happen between two people (so perhaps the Greeks had some reason to quarantine their lepers after all). What is known is that the bacterium incubates in the respiratory tract for 2 to 5 years or even as long as 20 years (3). Only about five percent of those infected with Hansen’s disease actually develop the symptoms (1). The bacteria mainly affects the skin, nerves, and mucous membranes; leprosy is often called “the living death” because of the widespread and terrible effects on the human body (4). In the eyes, there is a loss of tear production, the eye can become numb and patients lose the ability to blink, all of which can lead to ulceration, dryness, and scratches from unnoticed particles (4). Hands and feet often become severely damaged or mutilated as a result of loss of feeling (4).

There are major two types of leprosy: lepromatous (multibacilliary Hansen’s disease) and tuberculoid (paucibacillary Hansen's disease) (1). Lepromatous leprosy (LL) is the more serious of the two types: the bacteria in this case affect many different areas of the body, including “skin, nasal mucosa, nerves, lymph, liver, muscles, eyes, testes, [and] bone marrow”(3). The first noticeable symptoms are likely to be either hair loss or change in sensory function caused by nerve damage (3). Lesions are very painful and include macules, papules, and nodules (3), where macules are flat lesions with varying color, papules are conically shaped lesions of the same color as the skin, and nodules are lesions larger than papules. Skin thickens all around, with particular thickening in the nasal mucous membranes, which is accompanied by nosebleeds. Other symptoms include testicular atrophy in males, an enlargement of the breasts in both sexes, and hair loss (3).

Tuberculoid leprosy (TL) is a much less painful experience; lesions are anaesthetic ( they aren’t painful) but can range from one centimeter to covering large swaths of the body (3). Skin will be tender to the touch and pigmented from healed lesions. Overtime, sensation will be lost from the hands, feet and face. Beyond these two major types of leprosy are all sorts of in between, or borderline, varieties, which share symptoms of one or both of the two major types.

Today, leprosy is treated with three different drugs: dapson, rifampin and clozfazimine. The first two drugs are antibiotics, while clozfazimine acts as an anti inflammatory to help control the adverse reaction of the drug treatment. This reaction occurs when Mycobacterium leprae dies so quickly that the dead bacteria builds up in the nerves before the body is able to remove it. It is necessary to treat the reaction with aspirin or even prednisone to prevent severe nerve and tissue damage in the hands, feet and eyes. As of late, there is no vaccine.

Most of those infected by leprosy live in third world countries, with Brazil, Madagascar, Mozambique, Tanzania, and Nepal reporting 90% of cases (2). Even though approximately 95% of the world’s population is estimated to have an immunity to leprosy, 91 countries reported cases of leprosy in 1999 and 2000, and the disease is endemic in 24 of those countries, with India accounting for 51% of newly detected cases worldwide and 71% of total cases worldwide (4). At highest risk are those living in impoverished conditions without a clean source of water or a sufficient diet, or those with diseases (such as HIV) which compromise the immune system. Approximately 150 people per year are diagnosed with leprosy each year in the United States (4). As of 2007, the prevalence of new cases of leprosy is 224,717 people per year (7).

Leprosy is still a little understood disease among scientists: new breakthroughs in the treatment of leprosy have been few and far between in the 20th century (4). The origins of leprosy are unclear, though it seems to be distantly related to tuberculosis. This connection is evidenced by the vaccine BCG, traditionally used to treat tuberculosis, which has been shown to have some preventative effects when applied to leprosy-prone populations. Also, as I mentioned earlier, another mystery of leprosy is that even though we know that the bacteria likes to incubate in the respiratory tract, it is unclear how it moves from the respiratory tract to the infection of the nerves of the body and the dermis (5). The organism has also never been cultured in the laboratory (9), and only recently (recent being the 20th century) were scientists able to inflict in and study the disease in monkeys, though after eleven generations it was becoming more and more difficult to continue to culture the bacteria (6). Adding this to the fact that it takes a long time for the bacterium to incubate, it is very difficult to track the growth of leprosy and to predict the pattern of infection amongst a population.

What is clear is that one’s genetic makeup is significant in the transmission of the disease; links have been shown between certain genes and the expression of the two different types of leprosy (5). Susceptibility, on the other hand, seems to lie between several genes and varies across populations; there is no clear conclusion on this point (5). It is also rare for a parent and a child in the same family to both have the disease; of 348 parents in Malawi infected with leprosy, only one of them had an afflicted child. Results of treatments for leprosy also give us some evidence for the role of genes in the prevalence of leprosy; for example, the aforementioned BCG vaccine’s rate of protection against leprosy varies widely, from 20% in some Burmese populations to 80% among other African groups (5). This suggests two conclusions: 1.) that the types of leprosy bacterium vary from population, making leprosy that much harder to treat and eradicate permanently; or 2.), that certain races are more susceptible to different types of leprosy, a theory which can be bolstered by other trends; for example, Chinese are more susceptible than Africans to the lepromatous kind of leprosy (8). 

New research about leprosy needed because the bacterium has begun to develop a resistance to the antibiotics used, though the current treatment kills 99.9% of bacteria (for example, when dapson was first discovered to be an effective treatment for leprosy, it garnered widespread use and in turn, the bacterium became increasingly resistant to dapson). If a permanent solution to leprosy is to be found, scientists will need to move beyond antibiotics, pick the bacterium apart and figure out how it works in order to develop an effective vaccine. A vaccine will succeed in ways where the drugs cannot: because leprosy still carries a huge stigma in affected areas, people who get the disease oftentimes do not report it and will try to hide their disease, leading to a furtherance of the existence of the bacterium. With a vaccine, we may approach the elimination of the bacterium by preventing the disease in all (no reports of the disease needed, no stigma attached). For now, however, leprosy contines to be the "living death", scourge of the Third World.



1) "What is Hansen's Disease?" ESSORTMENT. 2002. PageWise, Inc. <>. 

 2) "Hansen's Disease (Leprosy)." Department of Health and Human Services: Centers for Disease Control and Prevention. 12 Oct. 2005. CDC. <>.

3) Kemp, Charles. "Leprosy (Hansen's Disease)." Infectious Diseases. Apr. 2006. Baylor University. <>.

4) American Leprosy Missions: Deliver the Cure. 2007. American Leprosy Missions. <>. 

5) Fine, P E. M. "Implications of Genetics for the Epidemiology and Control of Leprosy." Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 31 Oct. 1988: 365-376. JSTOR. <>. 

6) "Leprosy Germs Grown in Laboratory for First Time." The Science News-Letter: 299. JSTOR. <>. 

7) "Leprosy Today." 2007. World Health Organization. <>.

8) Marley, Faye. "Science Cleanses the Leper." Science News 29 July 1967: 110-111. JSTOR. <>. 

9) Baron, Samuel, ed. Medical Microbiology. 4th ed. 1996. <>.