Spatial neighborhood patterns of pulmonary tuberculosis in a large urban area: the case of Santiago, Chile

In recent years, global concern about tuberculosis (TB) has grown due to the slow progress in achieving control goals, with a record number of cases reported worldwide in 2022. This study analyzed the spatial distribution of all pulmonary TB cases reported between 2016 and 2020 in the Gran Santiago (n = 3348), Chile's largest urban area. Cases were geocoded using an automated cascade method (Bing Maps, Google Maps, and manual verification) and aggregated at the neighborhood level. To detect spatial clusters, we estimated gender-adjusted rates, assessed spatial autocorrelation using Moran's I, and identified spatial clusters with Flexible Scan Statistics. Bivariate analyses were used to explore associations with demographic and residential variables. We observed higher incidence rates in males compared to females (13.23 vs. 7.03 per 100,000), with no statistically significant changes over time. A total of 29.4% (n = 984) of all cases were concentrated in 11 significant spatial clusters. These clusters were characterized by a higher proportion of immigrant, Indigenous, and older populations, along with indicators of precarious living conditions, including overcrowding and tenement housing. Identifying spatial patterns of pulmonary TB can support the design of targeted, community-based case-finding strategies in urban settings, particularly in populations at higher social and structural risk.