London School of Hygiene & Tropical Medicine

Many countries have made a significant step towards malaria elimination, with prevention efforts saving millions of dollars in healthcare costs, according to the World Health Organization (WHO) World Malaria Report 2015.

New estimates reveal that more than half (57) of the 106 countries with malaria in 2000 had achieved reductions in new malaria cases of at least 75% by 2015.

In sub-Saharan Africa, the reduction in malaria cases has had a huge economic benefit, saving an estimated US$ 900 million in case management costs from 2001-2014. The largest savings were attributed to insecticide-treated mosquito nets, followed by artemisinin-based combination therapies and indoor residual spraying.

Despite progress, significant challenges remain - including insecticide and drug resistance. The report states that 60 of the 78 countries that monitor insecticide resistance have reported mosquito resistance to at least one insecticide used in nets and indoor spraying. Of these, 49 reported resistance to two or more classes of insecticide. Parasite resistance to artemisinin (the core compound of the best available antimalarial medicines) has been detected in five countries of the Greater Mekong subregion.

Prof David Schellenberg, Professor of Malaria & International Health at the School, said: "WHO's 2015 World Malaria Report shows the solid progress being made in the fight against malaria. We recognise the considerable investments being made to curb this disease and celebrate the 6.2 million lives saved as a result since 2000. However, much remains to be done - 438,000 deaths a year from a preventable and treatable infection is just not acceptable. Further investment is needed to ensure progress continues towards the ultimate goal - a world free of malaria."

Prof David Conway, Professor of Biology at the School, added: "This annual effort by the WHO to collate and present global trends in malaria is very important. However, there are serious problems with the quality of data available for many of affected countries. The information from some of these countries in the WHO report appears quite different from the actual situation, as assessed by a few malaria research projects that use high quality laboratory and recording methods. These differences include the type of malaria being reported, some country reports omitting to recognise or underestimating the proportion of cases caused by species apart from Plasmodium falciparum. There is a desperate lack of quality in the detection and counting of cases in countries with poorly organised health facilities, so they produce supposed data that are quite inaccurate and useless for determining trends. There needs to be a change of culture in many countries towards recognising the need for reliable information."

Dr Jo Lines, Reader in Malaria Control and Vector Biology at the London School of Hygiene & Tropical Medicine, said: "In the last decade, humankind has made remarkable progress in its war against malaria, and the latest World Malaria Report from the WHO Global Malaria Programme shows that this progress is continuing steadily. There have been further increases in coverage with insecticidal nets, further reductions in the prevalence of malaria infection, and further declines in death and disease due to malaria. The areas where the disease is endemic are shrinking: malaria is in retreat in Latin America, and many parts of Asia, and in Southern Africa. About 85% of malaria deaths still occur in tropical Africa, where the mosquitoes are most efficient. Even in these heartlands, however, our interventions have brought about a huge reduction in the prevalence and incidence of infection. About 78% of this reduction in cases is due to vector control.

"We must not be complacent, however. These achievements will be sustained and extended only if the coverage with effective interventions sustained and extended, and our ability to do this is threatened by fading political will, and insecticide and drug resistance. Sustained political will is needed to keep on replacing the nets that are out there now. If we fail to do this in tropical Africa, intense malaria transmission is likely to return, and there is a risk of severe epidemics, especially in places where the reduced malaria exposure of the last few years has caused the human population to have a reduced level of anti-malaria immunity. Insecticide resistance has now spread to every African country, and in some places the mosquitoes can survive doses of insecticide 1000-fold higher than before. As far as we can see, the nets are still working right now, but we don't know how long this will continue. To counter the threat of insecticide resistance, we need new insecticides, and we are making some progress with this. However, we also need to optimise the way we use our insecticides, in order to delay resistance and prolong their effective life. There has not been much progress here.

"Nevertheless, overall, the 2015 World Malaria Report brings good news. One particular point to celebrate is that our ability to monitor what is happening is also steadily improving: there are still major gaps in the data, but they are fewer and smaller than a decade ago, and there is less uncertainty and disagreement about what the data mean. It is important to note the critical role played by WHO, not only in collating this data and producing the report, but also in its global normative role: developing technical standards and policy recommendations, based on evidence and supported by expert consensus, in order to guide malaria control programmes and their donors. It is a thankless but indispensable task."

The WHO's annual World Malaria Report assesses global and regional malaria trends, highlights progress towards global targets, and describes opportunities and challenges in controlling and eliminating the disease. The report's key findings are summarised on the WHO website.

Related links:

• Paving the road to a malaria-free world
• Malaria Centre