LEPROSY NEW CASE DETECTION TRENDS AND THE EFFECT OF PREVENTIVE INTERVENTIONS IN PARÁ STATE, BRAZIL: A MODELLING STUDY

Introduction and Objective. Leprosy remains a public health problem in Brazil. Although the overall number of new cases is declining, there are still areas with a high disease burden, such as Pará State. We aim to predict future trends in new case detection rate (NCDR) and explore the potential impact of contact tracing and chemoprophylaxis on NCDR in Pará State. Methods. We used SIMCOLEP, an existing microsimulation model for the transmission and control of M. leprae in a population structured by households. The baseline scenario was the current control program, consisting of multidrug therapy, passive case detection, and active case detection from 2003 onwards. Future projections of the NCDR were made until 2050 given the continuation of the current control program (i.e. baseline). We further investigated the potential impact of two scenarios for future control of leprosy: 1) discontinuation of contact tracing; and 2) continuation of current control in combination with chemoprophylaxis. Results and Conclusions. The modelled NCDR in Pará State after 2014 shows a continuous downward trend, reaching the official elimination target of 10 cases per 100,000 population by 2030. Systematic contact tracing in combination with chemoprophylaxis for contacts will reduce the NCDR by 40% and bring attainment of the elimination target two years forward to 2028. The NCDR of leprosy will continue to decrease in Pará State. Elimination of leprosy as a public health problem can possibly be achieved around 2030.