Leprosy or ‘Hansen’s disease’ is a chronic infectious condition that has been affecting mankind from ancient times. It affects the skin, peripheral nerves, upper respiratory tract, nasal mucosa, eyes, etc, and intimately results in progressive nerve damage, cosmetic disfiguration and debilitation (Wener, 2007). A person suffering from leprosy would be facing tremendous social stigmata, as the condition is said to be contagious and spreads from one person to another through several means.
However, researchers usually feel that the disease passes on from one person to another through respiratory droplets from the nose rather than contact (as the causative organisms is a bacilli most probable being transmitted through droplet infection) (NIAID, 2008). Scientists feel that broken skin could also help transmit the infection to others. People living in poor nations in which leprosy is endemic or in families with high incidences of the disease, are at a high risk of developing leprosy (CDC, 2007).
However, throughout the world, due to the improvements in treatment and identification of leprosy, the condition has been resolved in developed nations, and even in developing nations, except for a few pockets or cases of the disease, leprosy seems to be less of a problem. Leprosy is of two types, namely paucibacillary or multibacillary forms. The paucibacillary form is characterized by the development of minder symptoms including formation of hypo-pigmented skin lesions.
In the multibacillary form, symmetrical skin nodules, plaques, skin thickenings, etc are formed in various parts of the body including the nasal mucosa (NIAID, 2008). The actual incidence of Leprosy in the year 2002 throughout the world was 760000 new cases (CDC, 2007). About 100 new cases occurred in the US in 2002, and the majority of the cases of leprosy throughout the world in 202 recorded in Brazil, Madagascar, Mozambique, Tanzania, and Nepal (CDC, 2007). However, if the disability caused by the disease is studied, about 1 to 2 million people seem to be affected.
The condition tends to occur more often in tropical and sub-tropical areas (Wener, 2007). Cause Leprosy is caused by the bacteria Mycobacterium leprae (CDC, 2007). It was first identified by Hansen GA in Norway, way back in 1873 (NIAID, 2008). This organism tends to grow very slowly in the host, but outside the host, would not be able to grow (including a culture media). It is found to double its number only after 12 to 14 hours (NIAID, 2008). In humans, the symptoms can develop very slowly, even after 20 years.
In the laboratory, the bacteria can be grown only on animals, and hence, it is frequently difficult to study it. Some of the commonly used animals include armadillos (especially chimpanzees, sooty mangabeys, and cynomolgous macaques) and immune-compromised rats (NIAID, 2008). The bacteria M. leprae tends to affect the peripheral nerve, ski n and the inner lining tissues of the body (mucous membranes) (NIAID, 2008). One of the huge global concerns today is the emergence of drug-resistant cases of M. leprae bacilli causing leprosy (Wener, 2007).