Quantitative modelling for dengue and Aedes mosquitoes in Africa: A systematic review of current approaches and future directions for Early Warning System development

The rapid spread and growing number of dengue cases worldwide, alongside the absence of comprehensive vaccines and medications, highlights the critical need for robust tools to monitor, prevent, and control the disease. This review aims to provide an updated overview of important covariates and quantitative modelling techniques used to predict or forecast dengue and/or its vector Aedes mosquitoes in Africa. A systematic search was conducted across multiple databases, including PubMed, EMBASE, EBSCOhost, and Scopus, restricted to studies conducted in Africa and published in English. Data management and extraction process followed the ‘Preferred Reporting Items for Systematic Reviews and Meta-Analyses’ (PRISMA) framework. The review identified 30 studies, with the majority (two-thirds) focused on models for predicting Aedes mosquito populations dynamics as a proxy for dengue risk. The remainder of the studies utilized human dengue cases, incidence or prevalence data as an outcome. Input data for mosquito and dengue risk models were mainly obtained from entomological studies and cross-sectional surveys, respectively. More than half of the studies (56.7%) incorporated climatic factors, such as rainfall, humidity, and temperature, alongside environmental, demographic, socio-economic, and larval/pupal abundance factors as covariates in their models. Regarding quantitative modelling techniques, traditional statistical regression methods like logistic and linear regression were preferred (60.0%), followed by machine learning models (16.7%) and mixed effects models (13.3%). Notably, only 36.7% of the models disclosed variable selection techniques, and a mere 20.0% conducted model validation, highlighting a significant gap in reporting methodology and assessing model performance. Overall, this review provides a comprehensive overview of potential covariates and methodological approaches currently applied in the African context for modelling dengue and/or its vector, Aedes mosquito. It also underscores the gaps and challenges posed by limited surveillance data availability, which hinder the development of predictive models to be used as early warning systems in Africa.Author summary: Infections from dengue and other arboviral mosquito-borne diseases transmitted by Aedes mosquitoes are on the rise globally, with Africa being no exception. Their advances are driven by anthropogenic factors, such as rapid urbanisation, globalisation, and climate change. Yet, knowledge of dengue epidemiology and burden on the African continent, and how to enhance preparedness is scarce. Navigating the complexities of predicting the spread/outbreaks of the dengue or the presence/abundance of Aedes vector mosquitoes, is challenging due to the complex interactions between multiple factors involved in the transmission. Despite these challenges, significant progress has been made in developing various quantitative methods to predict spread and outbreaks in different regions in the world. Here, we conducted a systematic review to shed light on existing quantitative modelling approaches for dengue and/or its vector Aedes mosquitoes in Africa, focusing on methodology, data sources, covariates used, model performance and validation. Our study revealed several shortcomings in current modelling practices in Africa and emphasized the need for real-time primary predictor data and more comprehensive reporting of model development techniques and validation processes. This review offers an evidence-based framework for improving future modelling practices, to develop more accurate and robust dengue prediction models, tailored for African contexts.