World Malaria Report 2010: documenting progress towards malaria eradication

Malaria is infamously a disease of poverty. A map of the world’s nations designating those with the lowest per capita income roughly doubles as a map of malaria endemicity [1,2]. As economies strengthen, improvements in education, housing and medical services reduce the impact of this devastating parasitic infection. Better education improves public awareness of malaria, leading to changes in lifestyles and associated reductions in transmission risk; upgraded housing and infrastructure lessen contact with Anopheles mosquitoes and eliminate breeding sites; timely diagnosis and treatment curtail malaria infections, promoting health and reducing transmission; and increasing financial resources support expanded vector control programs and stronger research, resulting in more effective interventions. The gains of economic development, however, are countered by the natural resilience and adaptability of the Plasmodium organism, which is more difficult to eliminate in tropical than temperate regions owing to the potential for year-round mosquito activity, high vectorial capacity (often far exceeding the minimum required for continued transmission) and the tendency for the parasite to evolve resistance to drugs and the mosquito to insecticides.

It is within the complex setting of nations struggling to improve their standard of living and especially to reduce the burden of disease and death that the WHO has released its landmark World Malaria Report 2010 [101]. This 238 page, highly accessible document, rich with newly collected data, summarizes successes in the battle against malaria, as well as disquieting uncertainties regarding the future. The report credits more than 125 individuals and malaria control programs from 106 malaria-endemic countries with providing source data and an additional 65 staff and consultants with performing analysis, writing, editing and production. WHO Director General Margaret Chan authored an inspirational introduction and foreword, having led her organization to endorse worldwide malaria eradication in 2008. Her efforts coincide with a surge in funding for malaria control by the Global Fund, the World Bank, the US President’s Malaria Initiative, the governments of malaria-endemic countries, donor nations, agencies and supporting foundations, including the Bill and Melinda Gates Foundation, which famously sounded the call for eradication at the first Malaria Forum in October 2007. This concerted effort, gaining momentum throughout the past decade (‘scale up for impact’), has raised hopes for the stepwise elimination of malaria country by country, starting with those nations characterized by relatively low transmission rates and stronger economies situated on the malaria periphery and progressing to the malaria heartlands of sub-Saharan Africa, Asia, the Pacific region and America, with a long-term goal of eradication [3].

This unprecedented commitment of resources and effort hinges on the promise provided by new tools shown to reduce the transmission of malaria and to improve health outcomes. These include: insecticide-treated mosquito nets that kill mosquitoes in the home and protect sleeping families; indoor residual spraying of insecticides that reduces mosquito populations resting indoors; rapid diagnostic tests that improve the speed and accessibility of malaria diagnosis and reduce the burdens of unnecessary treatment; artemisinin-based combination therapy that pairs the most effective class of antimalarials (artemisinin derivatives such as artesunate) with a second drug to reduce the likelihood of drug resistance; and intermittent preventive treatment of pregnant women, infants and children with long-lasting agents such as sulfadoxine/pyrimethamine to reduce morbidity. With burgeoning financial support, the implementation of these new tools is growing throughout malaria-endemic areas.

The statistics provided by the report are impressive: two new countries have been certified by the WHO as malaria-free since 2008 (Morocco and Turkmenistan) and Albania has recently joined the list. Nearly 289 million insecticide-treated mosquito nets were delivered to sub-Saharan Africa between 2008 and 2010, enough to protect 578 million people. In Africa, 75 million individuals, or 10% of the population at risk, were also protected in 2009 by indoor residual spraying. These and other interventions across the world are linked to dramatic reductions in malaria incidence in many countries and to saving many lives.

The report presents these data in a well-organized and logical manner. The stated purpose of the report is to support the development of effective national malaria control programs. A secondary objective is to strengthen the business case for investing in malaria control. The introductory chapter provides an overview of the entire report. Next is an account of internationally agreed-upon goals, policies and strategies for malaria control including a call for an end to malaria deaths by 2015 (Chapter 2). There follows a description of resource requirements and trends in financing (Chapter 3), a summary of implementation programs for insecticide-treated nets (Chapter 4) and for malaria diagnosis, treatment and intermittent preventive treatment (Chapter 5) and finally an assessment of malaria burden including the evidence that malaria control activities have had an impact in each WHO region (Chapter 6). This last chapter estimates the number of cases and deaths by region and worldwide for the period 2000–2009, encapsulating the more detailed information available in the annexes. A strong point throughout the report is the description of the data collection and analysis techniques that generated the extensive graphs and tables. These analyses reveal many interesting trends and associations, such as the influence of international funding on domestic commitments and country-specific shortfalls in bednet distribution and artemisinin-based combination therapy availability. Chapter 6 is followed by 70 pages of detailed data from 24 selected countries or areas, providing a window into the tremendous diversity of issues facing worldwide malaria control nation by nation. There follows 12 annexes with supplemental material, including tables of ‘completeness data’ by country indicating gaps in the database and explaining the wide confidence intervals associated with morbidity and mortality estimates.

The report notes danger signals as well as successes. Progress in malaria control can be disrupted by civil disturbance, economic reversals, reductions in aid, policy changes, altered rainfall or natural disasters. Thus, after steady gains, malaria has resurged locally in three African countries, possibly caused by increased rainfall, aging bednets and/or pyrethroid resistance. Artemisinin resistance is emerging in several regions of southeast Asia, threatening our most effective class of antimalarial drugs. These events highlight the critical need for ongoing surveillance, assessment and research throughout every stage of the malaria campaign – surveillance to enable early detection of worrisome trends, assessment to provide the data needed for contextual revision of control strategies and research to develop new tools such as repellants, diagnostics, drugs and vaccines to consolidate gains and achieve country by country elimination.

Also of concern is the knowledge that in similar eradication efforts, such as polio and guinea worm, disease incidence has fallen steeply during the early stages of the campaign but then leveled off due to nonlinear effects [4–6]. For example, malaria may be easily controlled in accessible, economically stronger regions, but remain refractory in remote, poorly resourced areas such as border regions where the per capita expenditure required for elimination surges. A second nonlinear effect is a decrease in the proportion of clinically apparent cases, requiring point-of-care diagnostics more sensitive than those currently available in order to detect persistent, low-level infections in asymptomatic subjects. Moreover, once malaria constitutes a minority cause of outpatient visits and hospital admissions, government priorities may shift, allowing control apparatus including both staffing and infrastructure to languish, with expertise and resources diverted to more common causes of febrile illness. Finally, as malaria incidence diminishes, the reservoir of exposure-related natural immunity wanes across populations, setting up the potential for large epidemics. Thus, the early successes detailed in the World Malaria Report 2010, though commendable, could herald slower progress or even malaria resurgence in subsequent years, warranting intense vigilance. Another issue of concern is vivax malaria, where research lags and where intensive and sustained interventions are needed to counter this parasite’s ability to relapse and its early production of transmissible gametocytes in advance of clinical illness. As a result of these many factors, slower but hopefully ongoing progress, punctuated by setbacks due to natural forces or to temporary shortcomings in control efforts, would be a realistic expectation for the long term.

Stepping back to view the big picture, while the report notes 19 million fewer cases of malaria in 2009 relative to the peak in 2005, this represents only an 8% reduction, with the total number of cases remaining well within the confidence limits of every estimate made during the past decade. Moreover, the reduction in the number of cases has often been smallest in the nations with the highest populations and incidence rates. Several large, populous countries in Africa showed only modest progress and received less aid per capita than smaller countries. While all are anxious to see big improvements in malaria control within a short period of time, it is of paramount importance to manage funder expectations in preparation for a sustained and balanced campaign, recognizing that malaria has plagued human kind for millenia and will not be easily dislodged without increases in funding and appropriate targeting of global malaria control investment [7].

While it seems irrefutable that the application of new tools has caused reductions in morbidity, mortality and transmission, as detailed in the World Malaria Report 2010, human intervention is superimposed on poorly understood biological cycles that may independently elevate or diminish malaria risk based on changing climates or ecologies. Thus, the data are inherently descriptive, making a very strong case for but not proving the link between intervention and reductions in disease.

Like pushing the fabled stone of Sisyphus, the efforts described in the World Malaria Report 2010 attempt to crest the ridge-top through brute force and persistence, imposing a degree of public health discipline on a single disease that is not necessarily concordant with a nation’s overall economic strength. The campaign aims to succeed because the tools at its disposal are substantially more potent and diverse, there is growing support from malaria-free, economically prosperous nations as well as malaria-endemic nations, and the eradication plan is better informed than the first WHO campaign, which was abandoned in 1973 after 18 years of effort. If transmission rates are suppressed below the threshold needed to sustain the malaria lifecycle, the heavy stone will roll down the far side of the mountain signaling freedom from malaria for all and marking one of the greatest achievements in human history. This could be expedited if organizations and communities battling malaria work closely with those battling HIV and other scourges, a sensible union of efforts as the world emerges from a period of economic depression. If cooperation and resources fall short, however, the heavy stone could roll back the other way, an outcome hard to countenance. In its essence, the World Malaria Report 2010 is an impassioned plea to the world community to join forces and strengthen resolve in this remarkable endeavor to free humanity from one of its greatest burdens.

Information resources

For more reading on worldwide efforts to eradicate malaria, see special issues or themed sections of:

• • The Lancet – Malaria Eradication: www.thelancet.com/malaria-elimination

• • PLoS Medicine – Global Research Agenda for Malaria Eradication: www.malariaworld.org/blog/special-issue-plos-medicine-global-research-agenda-malaria-eradication

• • Clinical Microbiology and Infection – Malaria elimination: http://onlinelibrary.wiley.com/doi/10.1111/clm.2011.17.issue-11/issuetoc

Disclaimer

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, the Department of Defense, nor the U.S. Government.

Financial & competing interests disclosure

Both authors are military service members and prepared this manuscript as part of official duties. Title 10 U.S.C. §105 provides that ‘Copyright protection under this title is not available for any work of the United States Government.’ Title 10 U.S.C. §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties. This work was supported by work unit 6000.RAD1.F.A0309 (Malaria Vaccine Research). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.