AN EPIDEMIOLOGIC-STUDY OF LEPROSY INFECTION BY SEROLOGY AND POLYMERASE CHAIN-REACTION

A population-based study has been carried out in two adjacent villages in a highly leprosy-endemic area of South Sulawesi, Indonesia; The pr evalence of clinical leprosy was 10.0 per 1000 inhabitants. A total of 1015 serum samples and 1228 nasal swab specimens were collected. IgM antibodies in blood to phenolic glycolipid-I (PGL-I) of Mycobacterium leprae were demonstrated by the gelatin particle agglutination test (M LPA) and by indirect ELISA (IgM-PGL). IgG antibodies to PGL-I (IgG-PGL ) and lipoarabinomannan-B (IgG-LAM) were measured by indirect ELISA. T he presence of M. leprae in nasal swab specimens was established by a polymerase chain reaction (PCR). The seropositivity rates in the popul ation were 32% for MLPA, 30.8% for IgM-PGL, 6.7% for IgG-PGL, and 11.6 % for IgG-LAM. Seropositivity rates for MLPA and IgM-PGL were highest in the younger age groups. There was no difference in seropositivity i n any of the tests between household contacts of leprosy patients and noncontacts. The seropositivity rates in the MLPA and IgM-PGL were not randomly distributed among all households. The presence of M. leprae by PCR was demonstrated in 7.8% of the nasal swab specimens. No correl ation was found between the results of the PCR and serology. This stud y indicates that M. leprae is widespread in the population, and that i n endemic areas many individuals carry M. leprae in their nasal caviti es without having obvious symptoms of leprosy.