The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015

September 18, 2015

Abstract: 

Background: In the midst of an escalating malaria public health disaster, the year 2000 marked a turning point in multilateral commitment to malaria control in sub-Saharan Africa, catalysed by the Roll Back Malaria initiative and the wider development agenda around the United Nations Millennium Development Goals (MDGs). The 15 years since have seen international financing for malaria control increase approximately twentyfold1, enabling widespread but uneven scale-up of coverage of the main contemporary malaria control interventions: insecticide-treated bed nets (ITNs), indoor residual spraying (IRS), and prompt treatment of clinical malaria cases with artemisinin-based combination therapy (ACT).

The effect of malaria control is poorly understood: Despite its importance, current knowledge on the nature and drivers of changing endemicity in sub-Saharan Africa is remarkably weak. National health records in 32 highly endemic countries (together accounting for about 90% of the global malaria burden) are considered inadequate to assess trends in malaria cases1. This stems from low care-seeking rates (many malaria cases are not seen at formal health facilities), incomplete record keeping and curation (many recorded cases are never captured in surveillance databases), and historically poor access to parasitological diagnosis (malaria cases were often diagnosed presumptively with poor specificity).

Figure 1: Changes in infection prevalence 2000–2015.

a, PfPR2–10 for the year 2000 predicted at 5 × 5 km resolution. b, PfPR2–10 for the year 2015 predicted at 5 × 5 km resolution. c, Absolute reduction in PfPR2–10 from 2000 to 2015. d, Smoothed density plot showing the relative distribution of endemic populations by PfPR2–10 in the years 2000 (red line) and 2015 (blue line). The frequencies on the vertical axis have been scaled to make the densities visually comparable. The classical endemicity categories are shown for reference in green shades. Results shown in all panels are derived from a Bayesian geostatistical model fitted to n = 27,573 PfPR survey points; n = 24,868 ITN survey points; n = 96 national survey reports of ACT coverage; n = 688 country-year reports on ITN, ACT and IRS distribution by national programs; and n = 20 environmental and socioeconomic covariate grids. Maps in a–c are available from the Malaria Atlas Project (http://www.map.ox.ac.uk/) under the Creative Commons Attribution 3.0 Unported License.

 

Conclusions:The efforts of the international community over the past 15 years have reduced malaria risk levels for many millions of people, and large regions of Africa are now in a position to consider elimination strategies. Despite this progress, many millions of people remain at risk of malaria disease and death in Africa in 2015. This analysis demonstrates that current malaria interventions have been highly effective at reducing prevalence and incidence across the continent, and provides strong support for sustaining and increasing access to these interventions as a cornerstone of post-2015 control strategies. This will need to be coupled with a redoubling of efforts to delay the spread of drug and insecticide resistance, tools for addressing the residual transmission that persists in some regions despite high vector control coverage, and concerted local programs to systematically detect and eliminate the remaining parasites.