Molecular Detection of Mycobacterium leprae and the Process of Infection and Illness in Contacts of Leprosy Patients: A Systematic Review.

Various techniques have been used for the molecular identification of Mycobacterium leprae (M. leprae). The aim of this review was to identify the relationship between the molecular presence of M. leprae and the process of infection and/or illness of contact of leprosy cases. A systematic review was carried out by searching the Medical Literature Analysis and Retrieval System Online (MEDLINE), Cochrane Library, Embase, Scopus, Web of Science and the Latin American and Caribbean Health Sciences Literature (LILACS) databases in January 2024. The studies were selected by two pairs of reviewers. Observational cross-sectional, case-control and cohort studies were included. A descriptive synthesis of the results by category was carried out. A total of 443 studies were identified, and 36 were included in the review. Twelve molecular targets were tested to identify the presence of the bacillus. A relationship was established between the identification of M. leprae DNA and factors related to the index case, housing characteristics, living conditions, epidemiology and anti-PGL-1 serology. None of the studies identified evaluated the molecular viability of M. leprae among contacts. The detection of M. leprae DNA alone does not necessarily predict the development of infection or clinical illness among contacts.