Leprosy relapse near pilgrimage sites in the Cariri region of Brazil.

Background: Leprosy relapse remains a challenge to Brazil's elimination efforts, particularly in regions where Mycobacterium leprae persists in the environment. While multidrug therapy (MDT) is effective, patients exposed to ongoing transmission may develop reinfections over time. This study investigates whether proximity to pilgrimage sites influences leprosy relapse in the Cariri region.

Methods: Leprosy relapses in the Cariri region (2010-2022) were georeferenced based on patients' residences. A geostatistical model assessed relapse proximity to pilgrimage sites, classifying cases (2-18 km) and controls (18-102 km) by spatial dependence. Logistic regression assessed relapse odds near pilgrimage sites, comparing reinfections (≥5 y) to insufficient therapy (<5 y), adjusted for age, gender, cure outcome, disease severity and patient mobility.

Results: A total of 337 leprosy relapses were identified across 45 municipalities in the Cariri region. Spatial analysis indicated that individuals living near pilgrimage sites had nearly twice the odds of experiencing a relapse ≥5 y after MDT treatment (OR=1.76, 95% CI 1.09 to 2.85), supporting the hypothesis that pilgrimage sites may act as transmission hotspots.

Conclusions: Leprosy elimination in Brazil requires context-dependent measures. Pilgrimage sites, where individuals seek healing but may contribute to transmission, should be prioritized for active surveillance and targeted interventions.