DISTRIBUTION AND PERSISTENCE OF MYCOBACTERIUM-LEPRAE NASAL CARRIAGE AMONG A POPULATION IN WHICH LEPROSY IS ENDEMIC IN INDONESIA

In order to understand better the relationship among Mycobacterium lep rae, its transmission and the human host or the chain of infection whi ch may lead to the development of leprosy, we performed a population s urvey in which nasal carriage of M, leprae was determined by a specifi c polymerase chain reaction (PCR), 2 years after an earlier survey in the same population. 1923 persons were registered, 1171 were clinicall y examined for signs of leprosy, and 418 were tested by PCR. The detec tion rate of leprosy in the study area had not changed significantly d uring the 2 years' observation period since the introduction of multi- drug therapy, i.e. 6/1000 compared to 7.7/1000 2 years before. Of 6 ne wly detected cases, 5 were diagnosed as having paucibacillary leprosy. The presence of M. leprae could be demonstrated by PCR in 2.9% (12/41 8) of the persons. PCR positivity was not persistent over the 2 years. All the PCR positive persons identified in the first survey were nega tive in the second, indicating that M, leprae nasal carriage is transi ent. As in the previous survey, we found evidence for widespread M. le prae nasal carriage as determined by PCR among the general population in an area in which leprosy is endemic. In addition, our data indicate d that PCR positivity can occur in certain clusters in the community. This clustering seems to be time-dependent, not necessarily related to the presence of patients.