Urban malaria and population mobility in sub-Saharan Africa: systematic review and meta-analysis

Malaria control in African cities faces challenges mainly due to rapid and unplanned urbanization and the spread of the new urban malaria vector, Anopheles stephensi. By 2050, nearly 70% of the world`s population will live in urban areas, a significant increase from the current rate. This systematic review and meta-analysis map the epidemiology of urban malaria in sub-Saharan Africa (SSA). The review included individual participants data from studies conducted in urban settings among all populations to characterize and establish pooled estimates of the prevalence and risk factors, which would help guiding strategies for malaria control and elimination in urban settings.

An exhaustive literature search was done in PubMed, Medline EBSCO, Google Scholar, Science Direct, and Cochrane Library databases. The Joanna Briggs Institute (JBI) guidelines were followed for evidence selection, data extraction, quality assessment and presentation of findings. Peer-reviewed and gray literature published in English since 2000 focusing on urban malaria Epidemiology in SSA was included in the review. Microsoft Excel 2016 spreadsheet and Stata statistical package were used to extract and analyze data, respectively. Potential sources of heterogeneity and publication bias were assessed. A random effects model was employed for the meta- analysis.

Of the 2,468 records identified from various databases, 39 articles were selected for systematic review and meta-analysis. The overall pooled prevalence of urban malaria in SSA was 23.01% (95% CI: 19.42, 26.59; I² = 99.8%, p < 0.0001). Substantial heterogeneity was observed (I² = 99.8%), indicating considerable variability in population and methods employed. Among two studies included for analysis, a random effect model showed that odds of malaria infection were higher among study participants who had history of travel (POR = 4.17 (95% CI: 2.33, 7.46, I² = 75.5%, p = 0.002). Similarly, five studies were included in the review and showed that owning livestock in the house was associated with malaria infection in urban settings (POR = 4.1, 95% CI: 1.62, 10.39; I² = 75.3%, p = 0.044).

This systematic review and meta-analysis showed a high prevalence of urban malaria infection in SSA with high country-wise heterogeneity. While country-level differences contributed to this variability, other important sources of heterogeneity included variations in population included, method employed and population characteristics. The pooled estimate showed that having a travel history and owning livestock in the house were identified as factors associated with urban malaria infection. Therefore, effective urban malaria control requires an integrated and targeted approach that addresses socio-economic, environmental and behavioural drivers.