Questions & answers: World malaria report 2018

The World malaria report 2018 reinforces the message that the world is currently not on track to achieve two critical 2020 milestones of the WHO Global Technical Strategy for Malaria 2016–2030 (GTS): reducing malaria deaths and disease by at least 40% by 2020. We are particularly concerned by the report’s finding that, in 2017, there were an estimated 3.5 million more cases of malaria in the 10 highest burden African countries. Of the countries hardest hit by malaria, only India showed progress in reducing its disease burden.

Coverage of key interventions to prevent and treat malaria – such as insecticide treated nets (ITNs) and antimalarial medicines – has only marginally improved since 2015. Access to preventive therapies that protect pregnant women and children from malaria remains too low. And the burden of anaemia, especially among children who have malaria, remains unacceptably high.

• Read the World malaria report 2018
• Read the Global Technical Strategy for Malaria 2016-2030

Despite a levelling off in progress since 2015, the global malaria response is in a much better place than it was at the start of the century. There continue to be promising pockets of progress in countries that carry a high burden of malaria, such as India, where cases dropped by 24% in 2017 compared with 2016; in Rwanda, which recorded 430 000 fewer malaria cases in 2017 than in 2016; and in Ethiopia and Pakistan, where both countries has estimated decreases of more than 240 000 cases over the same period.

The report also reveals that, in a subset of countries that are nearing elimination, the pace of progress is quickening. In 2017, for example, 46 countries reported fewer than 10 000 indigenous malaria cases, up from 37 countries in 2010, and for the first time, China and El Salvador reported zero indigenous cases. Earlier this year, WHO certified Paraguay as malaria-free, the first country in the Americas to be granted this status in 45 years.

The World malaria report presents a comprehensive snapshot of global progress and trends in fighting malaria. Identifying why a specific country is not advancing as hoped would require in-depth country-by-country assessments, which is not the purpose of this report. WHO is planning to lead country-focused analyses in the highest burden countries over the next year.

At a glance, progress may have slowed for two reasons. First, funding for malaria control in most countries remains insufficient. The overall level of resources available in 2017, although slightly higher than in 2016, continues to fall short of our annual GTS funding target for 2020.

Inadequate funding has resulted in major gaps in coverage of core malaria control tools that prevent, diagnose and treat malaria. In 2017, for example, an estimated half of the population at risk of malaria in Africa did not sleep under a treated net. Importantly, most ITNs distributed in recent years were used to replace old nets, resulting in limited quantities to cover additional populations.

At the World Health Assembly in May 2018, the WHO Director-General, Dr Tedros Adhanom Ghebreyesus, called for an aggressive new approach to jump-start progress against malaria. A new country-driven response – “High burden to high impact” – will be launched in Mozambique on 19 November, alongside the release of the World malaria report 2018.

The approach will be driven by the 11 countries that carry the highest burden of the disease (Burkina Faso, Cameroon, Democratic Republic of the Congo, Ghana, India, Mali, Mozambique, Niger, Nigeria, Uganda and United Republic of Tanzania). Key elements of the new approach include:

• Political will to reduce the toll of malaria;
• Strategic information to drive impact;
• Better guidance, policies and strategies; and
• A coordinated national malaria response.

Catalyzed by WHO and the RBM Partnership to End Malaria, “High burden to high impact” builds on the principle that no one should die from a disease that is preventable and treatable. The support and engagement of all partners will be critically important to the success of this country-led approach.

Read High burden to high impact: a targeted malaria response

India – a country that accounted for 4% of global malaria cases in 2017 – is making significant progress in bringing down its malaria burden. As reflected in this year’s World malaria report, the country registered a 24% reduction in cases over 2016, largely due to substantial declines of the disease in the highly malarious state of Odisha, home to approximately 40% of all malaria cases in the country.

Success factors include rejuvenated political commitment, strengthened technical leadership, which focused on prioritizing the right mix of vector control measures, and increased levels of domestic funding to back efforts. A notable aspect of Odisha’s approach is its network of Accredited Social Health Activists, or ASHAs, who serve as front-line workers to deliver essential malaria services across the state, particularly in rural and remote areas (For more on Odisha’s progress in fighting malaria, and the role played by ASHAs, see the photo essay on India takes on malaria in its highest burden state.

Malaria cases in Venezuela have risen significantly over the past 3 years: 136 000 cases in 2015, 240 000 in 2016, and 411 000 in 2017. The increase is largely linked to the unaffordability of antimalarial drugs, weakened vector control programmes and the movement of malaria-infected persons in the gold-mining areas of Bolivar State into other areas of the country with malariaprone ecosystems.

The rise in malaria cases in Nicaragua (2200 in 2015, 6200 in 2016 and 10 900 in 2017) is mainly due to increased malaria transmission in a municipality in the country’s Atlantic region. Here, migration combined with environmental and socio-economic factors have created prime conditions for malaria-carrying mosquitoes.

After sustained progress in fighting malaria, Brazil has reported a significant jump in cases in the last two years, from 124 000 in 2016 to 189 000 in 2017. Increases were concentrated in several endemic states of the Amazon region, including in municipalities that had recently achieved significant reductions in transmission. A key challenge has been reaching remote and vulnerable populations with malaria prevention and control tools, such as diagnostic testing and treatment.

The special focus on anaemia is intended to raise awareness of malaria-related anaemia – a condition that, left untreated, can result in death, especially among vulnerable populations such as pregnant women and children under five.

Anaemia was once a key indicator of progress in malaria control and its prevalence was used to evaluate the efficacy of interventions. Recent years have seen a decline in awareness of the burden of malaria-related anaemia, despite its importance as a direct and indirect consequence of malaria. As a result, the prevalence of anaemia among populations vulnerable to the disease has not been reported consistently as a metric of malaria transmission and burden.

As highlighted in this year’s report, data from surveys conducted in 16 high burden African countries shows that, among children under 5 years of age, the prevalence of any anaemia was 61%, mild anaemia 25%, moderate anaemia 33% and severe anaemia 3%. Of children who tested positive for malaria, the prevalence of any anaemia was 79%, mild anaemia 21%, moderate anaemia 50% and severe anaemia 8%.

By spotlighting malaria-related anaemia in this year’s report, we are signalling the importance of paying attention to anaemia and, at the same time, the need to better focus the malaria response on pregnant women and children under 5.

Globally, more countries are moving towards zero indigenous cases: in 2017, 46 countries reported fewer than 10 000 such cases, up from 37 countries in 2010.

The number of countries with less than 100 indigenous cases – a strong indicator that elimination is within reach – increased from 15 in 2010 to 26 in 2017. China and El Salvador reported zero indigenous cases in 2017, a first for both countries. Algeria, Argentina and Uzbekistan have made formal requests to WHO for certification.

One of the key GTS milestones for 2020 is elimination of malaria in at least 10 countries that were malaria endemic in 2015. At the current rate of progress, it is likely that this milestone will be reached.

Looking at the WHO African Region, where malaria is heavily concentrated, we are seeing more people at risk of malaria being protected by insecticide treated bednets (ITNs). Information gathered from household surveys, ITN manufacturers and distributers, including through national malaria control programmes, point to a rise in both household ownership and use of ITNs.

For example, over the 2010–2017 period, the percentage of the population protected by an ITN increased from 33% in 2010 to 56% in 2017; household ownership of at least one ITN rose from 47% to 72%; and households with at least one ITN for every two people doubled from 20% to 40%.

However, coverage has only marginally improved since 2015, and we are far from reaching the target of universal coverage. Access of populations at risk of malaria to this core tool must be significantly expanded, particularly in high burden countries.

WHO takes resistance to any effective disease-cutting tool very seriously. We are working with all malaria-endemic countries to monitor the efficacy of artemisinin-based antimalarial drugs and insecticides.

Despite the presence of multidrug resistance in the Greater Mekong subregion, decreasing morbidity and mortality continue to be observed. Equally important to note is that the increase of malaria cases in the WHO African Region is not related to resistance to artemisinin-based combination therapies (ACTs), which remain fully effective as first-line treatments in these countries. Overall, the immediate threat of antimalarial drug resistance is low and most ACTs remain efficacious in all malaria-endemic settings outside the Greater Mekong.

Insecticide resistance is more widespread. Of the 80 malaria endemic countries that provided data for 2010–2017, resistance to at least one of the 4 insecticide classes in one malaria vector from one collection site was detected in 68 countries, an increase over 2016 due to improved reporting and three new countries reporting on resistance for the first time. In 57 countries, resistance to two or more insecticide classes was reported.

However, ITNs continue to be an effective tool for malaria prevention, even in areas where mosquitoes have developed resistance to pyrethroids (the only insecticide class used in ITNs). This was evidenced in a large multi-country evaluation coordinated by WHO between 2011 and 2016, which did not find an association between malaria disease burden and pyrethroid resistance across study locations in 5 countries.

Seasonal malaria chemoprevention (SMC) is a WHO-recommended preventive treatment course for children living in the Sahel, a subregion of Africa. SMC is administered by community health workers at monthly intervals to all children aged 3 to 59 months throughout the high malaria transmission season.

In 2017, an estimated 15.7 million children in 12 countries in the Sahel (Burkina Faso, Cameroon, Chad, Gambia, Ghana, Guinea, Guinea Bissau, Mali, Niger, Nigeria, Senegal and Togo) were protected through SMC programmes. However, 13.6 million children who could have benefited from this intervention were not reached, with overall coverage at 53% across the subregion. Common issues reported by countries include insufficient resource allocation and delayed disbursements of funding, which negatively impact the ability of countries to plan and procure medicines in time for the malaria transmission season.

WHO is calling on all countries in the subregion, and their development partners, to provide and sustain universal access to this important intervention for all children at risk of malaria.

WHO applies 3 methods for calculating estimates of malaria cases. One method uses routine data from countries without any adjustments; in other words, we use the data “as is”, directly from the country. This approach applies to countries that have a very low number of malaria cases, high-quality surveillance systems, and are near elimination.

The second method is for countries outside of sub-Saharan Africa, excluding Botswana, Ethiopia, Namibia and Rwanda, that have a good public health surveillance system but where a large proportion of patients seek care in the private sector or do not seek treatment at all. Here, adjustments for testing rates, reporting and treatment seeking rates are applied to the reported data.

The third method applies to most countries in the WHO African Region, where surveillance systems have been historically weak. To come up with a reliable estimate, we measure the relationship between parasite prevalence and case incidence within a specific area.

In many countries in the WHO African Region, which carries over 90% of the global malaria burden, improvements in surveillance systems are providing new insights. When better and more comprehensive data becomes available, previously-published WHO estimates are revised to reflect the new data from countries. What has not been updated or revised is the methodology used to arrive at the estimates included in the World malaria report.

It is important to state that as national surveillance systems improve, the existing WHO model used to estimate malaria cases – i.e. parasite rate to case incidence – is likely underestimating the actual number of cases in many countries in the WHO African Region. In March 2018, WHO convened an Evidence Review Group that reviewed the Organization’s malaria burden estimation methods and made several recommendations for improvements. These recommendations will be implemented in the next edition of the World malaria report.

Between 2010 and 2017, malaria deaths globally declined from 607 000 to 435 000. All regions except the Americas recorded reductions in mortality rates in 2017 when compared with 2010. The largest declines occurred in South-East Asia (-54%), Africa (-40%) and the Eastern Mediterranean (-10%). However, despite these gains, the reduction in mortality rates has slowed since 2015, reflecting the estimated trends in malaria case incidence.

We exercise caution regarding malaria mortality estimates as weaknesses in most malaria endemic countries’ civil, vital statistics (registration of deaths) and routine health information systems do not allow for reliable analyses of causes of death. This is further compounded by different estimation methods used by WHO and other organizations, resulting in estimates with substantially different mean values for the same year and wide confidence intervals. For these and other reasons, WHO has established an Evidence Review Group on malaria mortality to review existing data and methods to provide the Organization with advice on the best mortality estimation approaches to use in the future.