Worldwide malaria death figures - a gross underestimate, finds latest research

Published on February 3, 2012 at 3:39 PM · No Comments

By Dr Ananya Mandal, MD

According to latest research malaria kills twice as many people every year as formerly believed, taking 1.2 million lives and causing the deaths not only of babies but also older children and adults.

The study has reanalyzed 30 years of data on the disease using new techniques and hopes to change the global effort that has been under way to eliminate malaria. That ambition now looks highly unlikely by the UN target date of 2015. It also raises urgent questions about the future of the troubled Global Fund to Fight Aids, TB and Malaria, which has provided the money for most of the tools to combat the disease in Africa, such as insecticide-impregnated bed nets and new drugs. The fund is in financial crisis and has had to cancel its next grant-making round. The research comes from the highly respected Institute for Health Metrics and Evaluation (IHME), based in Seattle, and is published in the Lancet medical journal.

Dr Christopher Murray and colleagues systematically collected data on deaths from all over the world over a 30-year period, from 1980 to 2010, using new methodologies and inventive ways of measuring mortality in countries where deaths are not conventionally recorded. The work on malaria is part of a much bigger project which has already led to new estimates of the death rates of women in childbirth and pregnancy and from breast and cervical cancer.

Their figure of 1.2 million deaths for 2010 is nearly double the 655,000 estimated in last year's World Malaria Report. However they add that there is a downward trend that the World Health Organization’s report showed, as a result of efforts by donors, aid organizations and governments to tackle the disease. But remind that the decline comes from a much higher peak – deaths hit 1.8 million in 2004, they say. That means the interventions such as better treatment and bed nets are working, but there is much further to go than everybody had assumed.

The study also refutes conventional thinking on malaria – that almost all the deaths are in babies and small children under the age of five. The study found that 42% were in older children and adults. “You learn in medical school that people exposed to malaria as children develop immunity and rarely die from malaria as adults,” said Murray, IHME director and the study's lead author. “What we have found in hospital records, death records, surveys and other sources shows that just is not the case.”

Most deaths are still in children, but a fifth are among those aged 15 to 49, 9% are among 50- to 69-year-olds and 6% are in people over 70, so a third of all deaths are in adults. In countries outside sub-Saharan Africa, more than 40% of deaths were in adults. In Africa, though, the contribution of malaria to children's deaths is higher than had been thought, causing 24% of their deaths in 2008 and not 16% as found by a report by Black and colleagues, whose methodology was used in the World Malaria Report.

That means that malaria needs a higher priority if the millennium development goal of cutting child mortality by two-thirds between 1990 and 2015 is to be achieved, say the authors. They add, “That malaria is a previously unrecognized driver of adult mortality also means that the benefits and cost-effectiveness of malaria control, elimination and eradication are likely to have been underestimated.”

Professor Rifat Atun, director of strategy, performance and evaluation at the fund, said more than $2.5bn (£1.6bn) had been disbursed for malaria control between 2009 and 2011. By the end of 2011, 235m bed nets had been distributed. Money that had been pledged was still coming in, he said, which meant it would be able to invest substantially this year and next. “What we are not able to achieve is the rate of increase in investment of the last few years. The trajectory we have been able to establish will not be realized,” he said. “Given the new burden that Christopher Murray has been able to show, we really need to ramp up investments in malaria and that really needs more funding. The mortality figures are much, much larger. We need to double our efforts to address the burden that we have.”

The Department for International Development said, “We are committed to helping halve malaria deaths in at least 10 of the worst affected countries. We will do this by increasing the number of bednets used by women and children; improving the diagnosis and treatment of malarial; and strengthening health information systems to better monitor progress and target interventions.”

The Lancet's editor, Richard Horton, told the BBC, “Right now we don't actually have any reliable primary numbers for malaria deaths in some of the most ‘malarious’ regions of the world, so what numbers we have come from estimates. What this paper reports is a new way of estimating the number of malaria deaths, where they've used additional data sets and improved mathematical models from calculating mortality.” But despite what he calls the “disturbing” number of deaths recorded, he believes the underlying message of the report is that the disease can and is being controlled. “Over the past decade, 230 million cases of malaria have been treated and the same number of bed nets have been distributed to people at risk of malaria, and the result of that has been this huge downturn. So what we know is that we're actually able to turn off malaria with our existing interventions.”

Commenting on the new study, Professor David Schellenberg of the London School of Hygiene and Tropical Medicine said the researchers had “gone to great lengths to assemble information from a range of sources and to make adjustments for the inadequate data quality”. “We can argue about the strengths and weaknesses of their approach but should not be distracted by the details of the methods: however you look at it, far too many people are dying from malaria. The introduction of rapid diagnostic tests for malaria, recommended by the WHO in 2010 and increasingly available in endemic countries, affords an unprecedented opportunity to take the guesswork out of malaria diagnosis and to improve the reliability of information,” he added.

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