Malaria is killing almost twice as many people around the world than was previously thought, recent research has discovered.
According to scientists from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, US, more than 40% of the victims are older children and adults, challenging the belief that the vast majority of deaths occur among the under-fives.
The infectious disease claimed 1.2 million lives worldwide in 2010, according to the new research.
This is nearly twice the number cited in a report from the World Health Organisation (WHO) published last year.
Researchers analysed all available data on malaria mortality from 1980 to 2010.
Their findings, published in The Lancet medical journal, showed consistently higher death tolls than those featured in the 2011 World Malaria Report.
For children younger than five in Africa, death estimates were 1.3 times higher. Children and adults in Africa they were 8.1 times higher, and for individuals of all ages outside Africa they were 1.8 times higher.
Worldwide, 433,000 more people over the age of five had been killed by malaria than WHO estimates suggested.
"You learn in medical school that people exposed to malaria as children develop immunity and rarely die from malaria as adults," said Dr Murray. "What we have found in hospital records, death records, surveys and other sources shows that just is not the case."
On a more positive note, since malaria cases peaked in 2004 at 1.8 million, the number of fatal malaria cases have fallen each year since with an annual decline of more than 7% between 2007 and 2010.
"We have seen a huge increase in both funding and in policy attention given to malaria over the past decade, and it's having a real impact," said co-author Dr Alan Lopez, from the University of Queensland in Australia.
"Reliably demonstrating just how big an impact is important to drive further investments in malaria control programmes. This makes it even more critical for us to generate accurate estimates for all deaths, not just in young children and not just in sub-Saharan Africa."
However, with the larger number of deaths, the goal of reducing malaria mortality to zero by 2015 might be a little optimistic, the researchers pointed out.
"We estimated that if decreases from the peak year of 2004 continue, malaria mortality will decrease to less than 100,000 deaths only after 2020."