Assessing the Feasibility of an Intensified Extended Contact Survey (IECS) Compared to Passive Household Screening for Leprosy in Bangladesh

Bangladesh is among the 23 WHO priority countries for leprosy, with a new case detection rate of 21 per million population including children among new cases indicating recent transmission. We aimed to compare active versus passive case detection using geospatial tools. A cluster-randomized study was conducted across seven intervention and seven control districts. In the intervention arm, GPS coordinates of new cases were recorded, and contacts within a 75-m buffer were screened. Spatial cluster analysis using Kulldorff’s scan statistics was performed to identify hotspots. The main objective was to achieve early case detection in intervention areas, reflected in a lower proportion of new patients with grade 2 disabilities (G2Ds). A total of 347/382 (90%) index cases were enrolled in the intervention arm, compared to 380/462 (82%) in the control arm. Among household contacts, 7/1482 (5‰) new cases were found in the intervention area and 12/1565 (7.7‰) in the control area. Additionally, 18/25,720 (0.7‰) new cases were detected among neighbor contacts in the intervention arm. G2D proportions were not lower in the intervention arm (15%) than in the comparator arm (11%, p = 0.043). Comparable household contact cases were observed in both arms, with more cases emerging among neighbors in intervention districts. Eight spatial clusters were identified, including 288/844 (34%) index cases, with three significant clusters from 2022 to 2023. Screening within a 75-m buffer detected additional leprosy cases, though fewer than expected due to COVID-19 limitations. Targeting clusters for case detection and prophylaxis could strengthen transmission control efforts.