Worldwide malaria deaths may be almost twice as high as previously estimated, a study reports.
The research, published in the British medical journal the Lancet, suggests 1.24 million people died from the mosquito-borne disease in 2010.
This compares to a World Health Organisation (WHO) estimate for 2010 of 655,000 deaths.
But both the new study and the WHO indicate global death rates are now falling.
The research was funded by the Bill and Melinda Gates Foundation. It used new data and new computer modelling to build a historical database for malaria between 1980 and 2010.
The conclusion was that worldwide deaths had risen from 995,000 in 1980 to a peak of 1.82 million in 2004, before falling to 1.24 million in 2010.
The rise in malaria deaths up to 2004 is attributed to a growth in populations at risk of malaria, while the decline since 2004 is attributed to "a rapid scaling up of malaria control in Africa", supported by international donors.
While most deaths were among young children and in Africa, the researchers noted a higher proportion of deaths among older children and adults than previously estimated. In total, 433,000 more deaths occurred among children over five and adults in 2010 than in the WHO estimate.
"You learn in medical school that people exposed to malaria as children develop immunity and rarely die from malaria as adults," said Dr Christopher Murray of the University of Washington in Seattle, who led the study.
"What we have found in hospital records, death records, surveys and other sources shows that just is not the case."
The researchers also concluded malaria eradication was not a possibility in the short-term.
"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," they write.