Accounting for regional transmission variability and the impact of malaria control interventions in Ghana: A population level mathematical modelling approach
Abstract Background: This paper investigates the impact of malaria preventive interventions in Ghana and the prospects of achieving program goals using mathematical models based on regionally diverse climatic zones of the country. Methods: Using data from the District Health Information Management System of the Ghana Health Service from 2008 to 2017 and historical intervention coverage levels, ordinary non-linear differential equations models were developed incorporating transistions between various disease compartments for the three main ecological zones in Ghana. The Approximate Bayesian Computational sampling approach, with a distance based rejection criteria, was adopted for calibration. A leave-one-out approach was used to validate model parameters and the most sensitive evaluated using a multivariate regression analysis. The impact of insecticide treated bed nets and their usage and indoor residual spraying as well as their protective efficacy on the incidence of malaria were simulated at various levels of coverage and protective effectiveness in each ecological zone to investigate the prospects of achieving goals of the Ghana malaria control strategy for 2014-2020. Results: Increasing the coverage levels of both long lasting insecticide treated bed nets and indoor residual spraying activities without a corresponding increase in their recommended utilisation does not impact highly on averting predicted incidence of malaria. Improving proper usage of long lasting insecticide treated bed nets could lead to substantial reductions in the predicted incidence of malaria. Similar results were obtained with indoor residual spraying across all ecological zones of Ghana. Conclusions: Projected goals set in the national strategic plan for malaria control 2014-2020 as well as WHO targets for malaria pre-elimination by 2030 are only likely to be achieved if a substantial improvement in treated bed net usage is achieved coupled with targeted deployment of indoor residual spraying with high community acceptability and efficacy.