The prime cause of leprosy is infection by Mycobacterium leprae, which belongs to the same strain as the one that causes tuberculosis. It grows slowly and affects the skin, nerves and mucous membranes. The effect of the respective strain of mycobacterium is restricted to the skin on the feet, hands, mucosal membrane of the upper respiratory tract, the frontal portion of the eyes, and the testes.
It is believed that the affliction is transmitted via respiratory droplets. However, sometimes, it may spread without any physical contact with an afflicted individual. It may also be spread by armadillos, which function as the carrier organism for the affliction.
Other causes of leprosy are:
The risk factors of leprosy are not well established yet. This may be attributed to the fact that it is difficult to culture the strains of mycobacterium which cause leprosy, and there is not much research conducted on the causal organism. Though there is no significant scientific back-up to support this, some scientists believe that AIDS may lead to leprosy. It weakens the general body immunity, enhancing susceptibility to leprosy.