Mapping the incidence rate of typhoid fever in sub-Saharan Africa.

Background: With more than 1.2 million illnesses and 29,000 deaths in sub-Saharan Africa in 2017, typhoid fever continues to be a major public health problem. Effective control of the disease would benefit from an understanding of the subnational geospatial distribution of the disease incidence. Method: We collated records of the incidence rate of typhoid fever confirmed by culture of blood in Africa from 2000 to 2022. We estimated the typhoid incidence rate for sub-Saharan Africa on 20 km × 20 km grids by exploring the association with geospatial covariates representing access to improved water and sanitation, health conditions of the population, and environmental conditions. Results: We identified six published articles and one pre-print representing incidence rate estimates in 22 sites in 2000–2022. Estimated incidence rates showed geospatial variation at sub-national, national, and regional levels. The incidence rate was high in Western and Eastern African subregions followed by Southern and Middle African subregions. By age, the incidence rate was highest among 5–14 yo followed by 2–4 yo, > 14 yo, and 0–1 yo. When aggregated across all age classes and grids that comprise each country, predicted incidence rates ranged from 43.7 (95% confidence interval: 0.6 to 591.2) in Zimbabwe to 2,957.8 (95% CI: 20.8 to 4,245.2) in South Sudan per 100,000 person-years. Sub-national heterogeneity was evident with the coefficient of variation at the 20 km × 20 km grid-level ranging from 0.7 to 3.3 and was generally lower in high-incidence countries and widely varying in low-incidence countries. Conclusion: Our study provides estimates of 20 km × 20 km incidence rate of typhoid fever across sub-Saharan Africa based on data collected from 2000 through 2020. Increased understanding of the subnational geospatial variation of typhoid fever in Africa may inform more effective intervention programs by better targeting resources to heterogeneously disturbed disease risk. Author summary: Typhoid fever remains a significant health challenge in low- and middle-income nations, especially in sub-Saharan Africa. A comprehensive understanding of the disease's geospatial distribution is pivotal for its control—a gap previous studies overlooked. Addressing this, we undertook a study to chart the incidence of typhoid fever throughout sub-Saharan Africa. Using data from 2000 to 2022, we developed high-resolution maps with a granularity of 20 km by 20 km, detailing the spatial distribution of typhoid incidence. Our findings reveal pronounced disparities in typhoid incidence across different geospatial tiers: from local communities to entire nations and regions. Particularly, Western and Eastern Africa registered the highest incidences, with children aged 5–14 years being the most vulnerable. Distinctively, countries such as South Sudan reported alarmingly high figures, whereas Zimbabwe had notably fewer cases. Such insights are indispensable for health policymakers at local, national, and global levels. Pinpointing the areas hardest hit by typhoid allows for a more strategic allocation of resources and interventions. Armed with this data, we're better positioned to fight typhoid effectively and safeguard lives in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]