The US President's Malaria Initiative, Plasmodium falciparum transmission and mortality: A modelling study

Abstract

Background: Although significant progress has been made in reducing malaria transmission globally in recent years, a large number of people remain at risk and hence the gains made are fragile. Funding lags well behind amounts needed to protect all those at risk and ongoing contributions from major donors, such as the President's Malaria Initiative (PMI), are vital to maintain progress and pursue further reductions in burden. We use a mathematical modelling approach to estimate the impact of PMI investments to date in reducing malaria burden and to explore the potential negative impact on malaria burden should a proposed 44% reduction in PMI funding occur.

Methods and findings: We combined an established mathematical model of Plasmodium falciparum transmission dynamics with epidemiological, intervention, and PMI-financing data to estimate the contribution PMI has made to malaria control via funding for long-lasting insecticide treated nets (LLINs), indoor residual spraying (IRS), and artemisinin combination therapies (ACTs). We estimate that PMI has prevented 185 million (95% CrI: 138 million, 230 million) malaria cases and saved 940,049 (95% CrI: 545,228, 1.4 million) lives since 2005. If funding is maintained, PMI-funded interventions are estimated to avert a further 162 million (95% CrI: 116 million, 194 million) cases, saving a further 692,589 (95% CrI: 392,694, 955,653) lives between 2017 and 2020. With an estimate of US$94 (95% CrI: US$51, US$166) per Disability Adjusted Life Year (DALY) averted, PMI-funded interventions are highly cost-effective. We also demonstrate the further impact of this investment by reducing caseloads on health systems. If a 44% reduction in PMI funding were to occur, we predict that this loss of direct aid could result in an additional 67 million (95% CrI: 49 million, 82 million) cases and 290,649 (95% CrI: 167,208, 395,263) deaths between 2017 and 2020. We have not modelled indirect impacts of PMI funding (such as health systems strengthening) in this analysis.

Conclusions: Our model estimates that PMI has played a significant role in reducing malaria cases and deaths since its inception. Reductions in funding to PMI could lead to large increases in the number of malaria cases and deaths, damaging global goals of malaria control and elimination.

Fig 1. Schematic of the modelling process.

Data inputs and sources (left column) are combined and linked to estimate the contribution of PMI and the impact of funding cuts on national-level intervention coverage (middle column). These estimates are then used as inputs in a dynamic transmission model to estimate the impact of changes in intervention coverage on epidemiological outcomes (right column). ACT, artemisinin combination therapy; DALY, Disability Adjusted Life Year; DHS, Demographic and Health Survey; IRS, indoor residual spraying; LLIN, long-lasting insecticide treated net; MICS, Multiple Indicator Cluster Surveys; NMCP, National Malaria Control Programme; PMI, President’s Malaria Initiative.

Fig 2. Map of PMI activities.

Individual countries and regions that have received PMI-funding and support are highlighted to reflect the level of funding from PMI in (A) sub-Saharan Africa and (B) the GMS over the period 2013–2015. The total regional assignment to the 6 GMS countries over this period is US$9.5 million. Estimated funding per population at risk over this period ranged from US$0.54 (Myanmar) to US$8.08 (Liberia). GMS, Greater Mekong Subregion; PMI, President’s Malaria Initiative.

Fig 3. The projected impact of PMI funding on past and future global malaria trends.

The (A) past trends (median estimates) in the global incidence of P. falciparum malaria given funding as occurred (black line) and estimate of the counterfactual trend had PMI support not existed (light blue line). The shaded area represents the cases averted due to PMI funding and (B) shows the associated estimates of death averted each year due to PMI funding. Projected estimates of the additional cumulative numbers of (C) cases (and 95% CrI) and (D) deaths (and 95% CrI) that would occur if PMI funding was reduced by 100% (dark green bars) or 44% (light green bars) over the 4-year period 2017–2020. PMI, President’s Malaria Initiative.

Fig 4. The health-system benefits associated with PMI funding.

PMI investment in malaria interventions reduces caseloads of national health systems with resulting (A) averted spending due to reduced treatments of clinical and severe cases by country. Without PMI investment, these health system gains are lost, potentially resulting in (B) the estimated cumulative malaria-related deaths in addition to those caused directly by removal of interventions due to health systems not being able to respond to increased caseloads. PMI, President’s Malaria Initiative.