Lepromatous Leprosy
Mycobacteria

What specific bacterium causes the disease?

Mycobacterium leprae (ML)

What are the specific characteristics of this particular bacteria?

Physical characteristics (i.e. shape, size, etc.)

It has parallel sides and rounded ends, it is 1-8 microns in length and 0.2-0.5 microns in diameter.

Behavioral characteristics (i.e. method of movement, method of attachment, etc.)

As it lives only intracellularly in vitro cultivation is not generally possible, but it has instead been grown in nine-banded armadillos because they, like humans, are susceptible to leprosy. Since Armadillos have a much lower body temperature than most mammals this allows the bacterium to often grow in their lungs, liver, and spleen while in human they grow only on the surface of the body where the temperature is lower than 37 C: the skin, peripheral nerves, eyes and mucosa of the upper respiratory tract

Where does this particular bacteria or virus live and function?

ML mainly lives in macrophages, giant cells that engulfs and digests cellular debris, foreign substances, microbes, cancer cells in a process called phagocytosis. Phagosomes or lysosomes (figure) are small acid vesicles (pH 5) similar to the stomach, that is more acid (pH1). When phagosomes are acid enough the ML dies when they are not acid enough the ML survives and a chronic disease develops.

To have or not to have the disease doesn't depend on the bacterium that is a weak invader but on the ability of the host to produce acid in his phagosomes.

The ability of the macrophages to produce acid depends on many factors:

• iron deficiency that is quite common everywhere but peaks in a country with a low average income and nutrition and in childhood
• low proteins daily intake
• hypothyroidism
• low level of sex hormones
• low levels of Vitamin D

As an example in Italy, people affected by leprosy are people that in their youth went to support people suffering from clinically symptomatic leprosy. They got the infection but not symptoms; 30 years after when they sex hormones dropped down they develop symptoms. In some cases earlier if by chance they develop hypothyroidism.

ML also lives in endothelial cells, the cells lining the inner face of the vessel wall

When endothelial cells are unable to kill ML, a local inflammation develops that leads to the vessel closure and death of the local tissues (nerve death and loss of sensitivity, skin ulceration)

Describe the symptoms of the disease?

Leprosy affects the skin and the nerves called the peripheral nerves. It could also affect the eyes and the thin tissue lining the inside of the nose. The main symptom of leprosy are:

• Discolored patches of skin, usually flat, that may be numb and look faded (lighter than the skin around)
• Growths (nodules) on the skin.
• Thick, stiff or dry skin.
• Painless ulcers on the soles of feet.
• Painless swelling or lumps on the face or earlobes.
• Loss of eyebrows or eyelashes.

How is the disease spread? How does a person protect themselves from the disease?

Leprosy research scientists still do not completely understand how leprosy is spread but most scientists believe that leprosy can be spread from person to person in infected respiratory droplets. While this may be one way in which leprosy is spread, more than 50 percent of the people who develop leprosy have no confirmed contact with an infected person. Factors that may influence how leprosy is spread include environmental conditions, the degree of susceptibility of the person, the extent of exposure.

Who is given credit for discovering this disease and when?

In 1873 G. H. Armauer Hansen in Norway discovered the bacteria causing leprosy, Mycobacterium leprae.

The history of this disease.

A. Where in the world has it affected people now and in the past?

Leprosy originated in East Africa or the Near East and traveled with humans along their migration routes.

B. How has this disease affected people now and in the past? (i.e. number of
deaths/year)

250,000 new cases of leprosy are still recorded annually, while in the past where millios

How has science been applied to this disease? How effective has science been with this disease? (this could be testing, medicine, etc)

Global leprosy control programs have been impressively successful, as more than 14 million people have been cured of the disease in the last 20 years through multidrug therapy (MDT) implemented by the WHO and others. Although this correlates to more than a 90% reduction in the prevalence rate, the chain of transmission has not been broken as approximately 250,000 new cases of leprosy are still recorded annually. This translates into a new case being documented approximately every 2 min, thus highlighting the need for continued commitment towards control of the disease and to leprosy research. The countries worst affected by leprosy, in terms of caseload, are India, Brazil, Indonesia, Bangladesh, Democratic Republic of the Congo, Ethiopia, Nepal, and Nigeria. (Full Paper)

As a matter of fact, the correlation between leprosy persistence and socio/economical condition is quite striking and depend on the hormonal and nutritional factor described before

A. Is there any current medical research being done on this disease? Explain and
provide details.

not too much as antibiotics are quite effective in treating the active diseases but the prevention depends on improvement in housing, hygienic conditions and other social constraints that depend on political more than medical options.

B. Are there vaccinations, or medication for this disease? Give details.
Is treatment available to all people regardless of socio-economic status?

In 1981, WHO recommended MDT (Multi Drug Treatment). The currently recommended MDT regimen consists of medicines: dapsone, rifampicin and clofazimine. This treatment lasts for six months for pauci-bacillary and 12 months for multi-bacillary cases. MDT kills the pathogen and cures the patient.

Yes, since 1995 WHO has provided MDT free of cost.

Give a prognosis for the patient. Provide a timeline if a person was and was not able to get treatment? Would they die regardless? How quickly? (You can count the day you received the project the day you got the disease. Would you be alive for the presentation?) This could be incorporated into the entire presentation.

The disease is usually a chronic one and leads to impairment of life quality more than to die.

9. What are the implications of using science (medicine or testing) and applying science
interacting with at least two of the following factors: moral, ethical, social, economic,
political, cultural or environmental?

Infectious diseases are a clear example of social behavior. We, humans, are sharing our environment with millions of different species of bacteria, protozoa, fungi usually without any arm for us and, probably, for them.
When a subset of humans living in a too dirty environment and/or with poor nutrition are unable to afford a usually armless bacterium this became a social problem, no longer a medical problem

10. What are some other important points concerning this disease? (Provide a minimum
of 3 additional points that could not be included in another question)

1. If properly nourished humans are fully resistant to the disease
2. the symptoms depend on the body iron availability measured as blood Hemoglobin
   • between 13/16 g Hb/dl no symptoms
   • between 11/13 g Hb/dl local inflammation and scarce nodules
   • between 9/11 g Hb/dl more widespread inflammation and nodules
   • under 9 g Hb/dl diffusion everywhere under the skin
3. people living in the rain forest spend most of their time in the shadow, without direct exposition to the sun with a consequent vitamin D deficiency.

Info Sources

WHO Leprosy

LEPROMATOUS LEPROSY.