World malaria report 2017

29 November 2017 | Q&A

Interview with Dr Abdisalan Noor, Team Leader of the WHO Global Malaria Programme's Surveillance Unit

There are several bright spots in this year’s report. First, more countries are accelerating towards elimination. In 2016, 44 countries reported less than 10 000 malaria cases, compared to just 37 countries in 2010. For the second consecutive year, the WHO European Region continued to be malaria-free.

We are seeing that coverage rates of access to tools to prevent malaria, such as insecticide-treated bednets (ITNs), have increased across most WHO regions in 2016 when compared to 2010. Another positive development is that testing of suspected malaria cases in the public health sector has gone up significantly in most regions since 2010. The largest rise was recorded in the African Region, where diagnostic testing increased from 36% in 2010 to 87% in 2016. However, across all malaria control interventions, we remain significantly below the targets for universal access.

Another piece of good news is that all regions recorded declines in malaria mortality in 2016 when compared to 2010, with the exception of the WHO Eastern Mediterranean Region where mortality rates have remained largely unchanged.

When we look closer at the data, the declining trend in malaria cases and deaths has stalled and even reversed in some regions, at least over the past three years. Equally concerning are continued gaps in coverage of basic prevention, diagnostic and treatment tools. As noted in the report, less than half of households in countries in sub-Saharan Africa have sufficient bednets, and only about one third of children in the African Region with a fever are taken to a medical provider in the public health sector.

Globally, we can safely say that after an unprecedented period of success, we are no longer making progress, which is supported by the data in this year’s report.

Identifying what is behind this trend is difficult to pinpoint; in any given country, there may be a multitude of reasons as to why the burden of malaria is increasing. Factors impacting progress could range from insufficient funding and gaps in malaria prevention interventions to climate-related variations. Without more data, it is challenging to identify, with any degree of certainty, a specific cause for the trends we are seeing. What is paramount now is taking this year’s malaria report as a wake-up call to stimulate action.

The notion of a crossroads is meant to sum up the current status of the global response to malaria: with current levels of funding, and coverage of current tools, we have reached the limits of what can be achieved in the fight against this disease. The fact that funding for malaria has plateaued, that the number of malaria cases in 2016 is similar to the number of cases in 2012, and that there remain huge gaps in coverage of key malaria control tools, all make clear that unless we increase our efforts, we are not going to see any further progress.

The proportion of the population at risk protected by indoor residual spraying (IRS), an intervention that involves spraying the inside walls of dwellings with insecticides, declined globally from a peak of 5.8% in 2010 to 2.9% in 2016, with decreases seen in all WHO regions. The number of people protected in 2010 was 180 million globally, reducing to about 100 million in 2016.

While there is yet no clear evidence of why this is happening, the decreases in coverage with IRS insecticides are occurring as countries change or rotate the chemicals they are using to try to prevent the spread of mosquitoes resistant to pyrethroids. Because alternative insecticides are more expensive than pyrethroids, increased funding for IRS is needed to maintain high coverage levels of this key intervention to rapidly reduce malaria transmission.

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

This year’s report provides a comprehensive situation analysis to capture, by WHO region, the status of antimalarial drug efficacy. Overall, the immediate threat of antimalarial drug resistance is low and artemisinin-based combination therapy (ACT) remains efficacious in all malaria-endemic settings. Insecticide resistance is more widespread, particularly pyrethroids, which are used in bednets and for indoor residual spraying.

A large multicountry evaluation coordinated by WHO between 2011 and 2016 showed that insecticides continue to be an effective tool for malaria prevention, even in areas where mosquitoes have developed resistance to pyrethroids. Further, there is no clear correlation between insecticide resistance and trends in malaria burden: some countries with resistance to pyrethroids have shown reductions in disease burden; others with less resistance have shown an increase. Ultimately, we need more data on the public health impact of insecticide resistance and further investments in this area.

No, the level of resources for malaria today is not sufficient to achieve the GTS targets. In 2016, an estimated US$ 2.7 billion was invested in malaria control and elimination efforts globally. This amount falls far short of our annual GTS funding target for 2020 (US$ 6.5 billion).

Overall, funding for malaria has levelled off since 2010 and, when analysed on a country-by-country per capita basis, funding has decreased for many high-burden countries, averaging below US$ 2 per person at risk annually. This level translates into fewer resources available to protect increasing populations at risk of malaria.

Despite the significant financial and economic crises experienced by many countries in the last few years, it is commendable that funding levels have remained stable. Still, to reach the 2020 targets of the GTS, increasing international financing and the contributions of endemic countries will be critical.

Yes, there is progress towards elimination, but the picture is mixed. Of the 91 countries with malaria transmission, 37 reported fewer than 10 000 cases in 2010 and, by 2016, that number rose to 44 countries. Kyrgyzstan and Sri Lanka were certified by WHO as malaria free in 2016, and Algeria, which remained malaria free in 2016, is now eligible for certification. Further, Argentina and Paraguay have begun the certification process.

One of the 2020 milestones of the WHO Global Technical Strategy for Malaria 2016- 2030 (GTS) is eliminating malaria in at least 10 countries that had malaria transmission in 2015. This means that a country must achieve at least one year of zero indigenous cases by 2020.

Early last year, WHO identified 21 countries with the potential to reach the 2020 elimination target. Our latest World malaria report shows that 11 of these countries have recorded increases in indigenous malaria cases since 2015, and 5 countries reported an increase of more than 100 cases in 2016 compared with 2015. Nonetheless, I am optimistic that at least 10 countries will meet the target.

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 very low 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 confirmation, 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. As a result, 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 African Region, improvements in surveillance systems are providing new insights. Data from these countries show that the existing WHO model used to estimate malaria cases – i.e. parasite rate to incidence – is likely underestimating the actual number of cases in many countries in the region. In 2018, WHO will do a comprehensive review of our malaria burden estimation methods for the African Region.

As part of the report’s section on threats to global malaria progress, we highlight concrete examples of the impact of conflict, humanitarian crises and political volatility on malaria control and elimination efforts. The 4 case studies on malaria epidemics in Nigeria, South Sudan, Yemen and the Bolivarian Republic of Venezuela demonstrate the fragility of progress and how gains can be reversed, even due to a short period of conflict or economic shocks. For example, Venezuela’s northern region was certified as malaria free in 1961, but last year it was the leading country in the Americas in terms of malaria burden. And in Yemen, due to the ongoing humanitarian situation, there is a reversal of progress under way with an increase in malaria cases seen in 2016.

Malaria represents one of the biggest success stories in recent times in terms of best value for money in public health. Millions of cases and deaths have been averted since 2000 through the scale-up of effective interventions.

Having said that, I am concerned that we have become complacent and expect progress to continue at the same levels of funding. Since 2013, the rate of progress has either slowed or stalled in many malaria-endemic countries. We have an opportunity to double down our efforts, and it is not just about increasing financing. It also means better and smarter ways to invest available resources. Closing gaps in coverage of the tools that we know work is absolutely critical, as is continued investment in the research and development of new tools.