Seroprevalence of Mycobacterium leprae antibodies among school children in Indonesia in 2023: a cross-sectional study.

BACKGROUND

Leprosy remains a significant public health issue in endemic regions, including areas in Indonesia. Transmission of Mycobacterium leprae (M. leprae) continues as clear from the almost stable annual number of new leprosy cases amongst which around 5% are children. To interrupt transmission of M. leprae, it is essential to identify and treat infection sources. This study aimed to assess anti-M. leprae phenolic glycolipid-I (PGL-I) IgM seroprevalence among school-aged children in rural and urban Indonesia, as a proxy for recent transmission. Additionally, associations between seropositivity and gender, socioeconomic status (SES), and helminth infection were investigated.

METHODS

We conducted a cross-sectional serosurvey among 637 children (ages 6-15) from schools in urban and rural areas of Sulawesi, Java, and Sumba, Indonesia. The PGL-I QURapid, a field-friendly and quantitative lateral flow assay, was used to detect anti-PGL-I IgM in fingerstick blood and plasma samples. Socioeconomic and health data, including helminth infection status and body-mass index z-scores (z-BMI), were also collected.

FINDINGS: The overall seroprevalence of anti-PGL-I IgM in children was 12.2% with significantly higher seroprevalence in rural (Southwest Sumba: 31.0%, Pangkajene: 11.2%) compared to urban areas (North Jakarta: 3.8%, Makassar city: 3.1%). Moreover, seroprevalence amongst children from low-SES schools was significantly higher (13.7%) than among those from high-SES schools (4.1%, P = 0.007). The presence of helminth infections were associated with significantly higher anti-PGL-I IgM levels (P < 0.0001), with 22.4% of helminth-infected children testing seropositive compared to 8.8% of non-infected children (P < 0.001).

INTERPRETATION: Our findings demonstrate a high anti-PGL-I IgM seroprevalence among rural, low-SES, and helminth-infected children in Indonesia, indicating elevated levels of M. leprae infection within these groups which again represents increased transmission rates in the population. These results underscore the need for integrated disease control strategies addressing both leprosy and helminthiasis, particularly in rural and economically disadvantaged areas. The PGL-I QURapid demonstrated to be an effective tool in serosurveys, able to aid the identification of areas with high M. leprae transmission rates (such as Sumba) and thereby support the implementation of targeted interventions in endemic regions.

FUNDING: This study was funded by a grant from the Q.M. Gastmann-Wichers Foundation (AG) and an internal grant from Atma Jaya Catholic University of Indonesia (MMMK).