Molecular Detection of Mycobacterium leprae in Household Contacts of Leprosy Patients in Barru Regency

Leprosy, caused by Mycobacterium leprae, remains a persistent public health challenge in endemic regions such as Indonesia. Despite global efforts toward elimination, hidden transmission through asymptomatic household contacts contributes to ongoing endemicity. Molecular detection methods, particularly polymerase chain reaction (PCR), have demonstrated superior sensitivity and specificity compared to conventional microscopy or clinical diagnosis.

A cross-sectional molecular survey was conducted at 12 primary healthcare facilities. Nasal swab samples were obtained from 37 leprosy patients (17 undergoing multidrug therapy, 20 released from treatment (RFT), and 89 household contacts. Deoxyribonucleic acid (DNA) extraction used the Presto™ Buccal Swab Kit, followed by PCR targeting the pra gene (531 bp).

Out of 126 samples, M. leprae DNA was detected in 14 (9.6%) by PCR analysis. Positive amplification was observed in 3 (11.8%) of 17 patients under treatment, 6 (17.1%) of 41 household contacts of patients under treatment, 1 (5.0%) of 20 RFT patients, and 4 (8.3%) of 48 household contacts of RFT patients. These findings highlight that household contacts of both active and previously treated leprosy patients may serve as potential reservoirs for ongoing transmission.

PCR-based molecular detection of M. leprae from nasal swabs offers a reliable tool for identifying subclinical infection and monitoring transmission dynamics in endemic settings. Integrating molecular surveillance into public health strategies can significantly enhance early diagnosis and accelerate leprosy elimination programs.