So, the more people you can treat, the more leprosy will decline. Leprosy takes various clinical forms, depending on the immune system of the person infected. People without any defences whatever against the bacilli develop multibacillary leprosy, while those with a stronger immune system come down with paucibacillary leprosy. This latter form is relatively harmless and as a rule non infectious. The most frequent form of leprosy, it accounts for between 70 and 80 percent of all cases.
Patients feel nothing in the affected area.
This sensory loss is very important for diagnosis because bacilli are often undetectable in skin smears. Unless treated with multiple drug therapy, persons suffering from multibacillary leprosy constitute the principal source of infection. In such persons the bacilli multiply almost unchecked. They are found in large numbers in the skin, peripheral nerves, inner lining of the nose, liver, spleen, lymph nodes, muscles and other organs. This form of leprosy is characterized by numerous shiny, non itching reddish nodules, tumours and raised patches with sloping edges.