Use of the polymerase chain reaction in the diagnosis of leprosy.

One of the main limitations for successful epidemiological control of leprosy is the lack of a method for its diagnosis in subclinical cases. Because of the long incubation period of the disease, liberation and spread of Mycobacterium leprae during subclinical stages-principally in cases of untreated multibacillary forms of leprosy-constitute the main source of infection. This report describes the use of the polymerase chain reaction (PCR) for the detection of M. leprae in different types of tissue samples (blood, lymph, nasal secretion and hair) from an individual who was suspected of having leprosy. Although no conclusive diagnosis could be made by traditional diagnostic methods, the individual was found to be infected with M. leprae after amplification of the bacterial DNA.