Histological acid fast stains revealed the pathogen. Leprosy is a bacterial disease characterized by lesions of the skin and mucous membranes and enlargement of peripheral nerves which can lead to anesthesia, muscle weakness and paralysis as well as changes in skin, muscle and bone. Leprosy can be classified on the basis of clinical manifestations and skin smear results. While classifying leprosy, it is particularly important to ensure that patients with multibacillary disease are not treated with the regimen for the paucibacillary form of the disease. M. leprae cannot be cultured in artificial media but can be grown in the footpads of mice, in the tissues of immunosuppressed rodents and in armadillos.
Man is the only reservoir of significance.
Mode of transmission is not clearly established, but household and prolonged intimate contact are important. Incubation period is known to be as short as 7 months, but probably averages from 3 to 6 years. A study which was conducted in California in 1980 revealed that 36 of the 91 cases of leprosy seen in the state that year were in individuals whose place of birth was Mexico. World prevalence is estimated at 11 million. The treatment recommended by WHO are a combination of rifampicin, clofazimine and dapsone for MB leprosy patients and rifampicin and dapsone for PB leprosy patients.