Mapping of regions with low tuberculosis notification and estimation of diagnostic gaps in Cameroon, evidence from OpenStreetMap and WorldPop data

Since 2012, Cameroon has introduced rapid molecular diagnostic tests for tuberculosis (TB). Despite this progress, WHO estimates indicate a TB diagnostic gap of 43% at the national level in 2019. This raises questions about the strategic allocation of available rapid molecular diagnostic tools to areas with lower TB notification. In a cross-sectional study, we combined Cameroon notification data on TB (2019), rifampicin-resistant (RR)-TB (2015-2019), as well as local TB risk factors, availability, intensity of use and accessibility of the Xpert MTB-RIF test with openly available geospatial datasets from OpenStreetMap and WorldPop. A mathematical model estimated TB and RR-TB incidence rates at the regional level. We compared these estimates with the number of reported TB cases to identify diagnostic gaps. Centre, East and Far North regions had the highest estimated TB incidence rates (400, 300 and 200 cases per 100,000 inhabitants, respectively), while South and Adamawa had the highest estimated RR-TB incidence rates (14.9 and 8.9 cases per 100,000 inhabitants, respectively). We report a national diagnostic gap of 53% and 50% for TB and RR-TB, respectively. These findings highlight the need to improve the allocation of diagnostic tools that follows the local disease burden in resource-limited settings to improve health equity.