Global, Regional, National Burden of leprosy, 1990-2021: A Systematic Analysis for the Global Burden of Disease Study 2021 and forecast to 2040

Background Leprosy (Hansen’s disease) is a chronic infectious disease caused by Mycobacterium leprae, potentially leading to nerve damage and disability if untreated. Prior research has not provided a thorough global perspective. Methods We evaluated global, regional, and national leprosy burdens and changes from 1990 to 2021 using Global Burden of Disease (GBD) 2021 data. We measured prevalence, incidence, and disability-adjusted life years (DALYs), stratified by sex, 20 age categories, 21 GBD regions, 204 nations/territories, and five SDI levels. We estimated annual percentage changes using age-standardized rates (ASR) and Bayesian age-period-cohort models, to reveal disparities, identify drivers, and project trends. Results From 1990 to 2021, there was a substantial reduction in global leprosy burden, with ASR decreasing from 11.73 to 4.84 per 100,000 population and ASR dropping from 1.65 to 0.58 per 100,000. Although males exhibited higher rates than females, both sexes demonstrated significant declines in burden. Regional analyses revealed marked disparities, with low-SDI regions experiencing the steepest declines while high-SDI areas saw slight upticks in incidence. Notably, South Asia, Tropical Latin America, and Central Sub-Saharan Africa remained hotspots, while regions with SDI ≥ 0.80 maintained near-zero burden. Age-specific patterns indicated higher prevalence and incidence rates in older age, particularly in low-SDI settings. Projections from 2021 to 2040 suggest continued declines in leprosy burden globally, although significant disparities between sexes and regions persist. Conclusions The growing global burden of NMSCs, particularly in high SDI regions and among older adults, underscores the urgent need for tailored prevention, resource allocation, and management strategies.