The World Health Organisation (WHO) dramatically cut its estimate today of how many people catch malaria every year, attributing the revision to changes in research methods.
The new report, however, kept the number of people who died from the disease broadly the same.
The United Nations agency said 247 million people were infected with malaria in 2006, the most recent year for which figures are available.
Its last estimate, issued three years ago and widely cited in government and pharmaceutical circles, was that 350 million to 500 million people caught the mosquito-borne disease a year.
"The change is due primarily to a refinement of calculation methods. It is not known if cases and deaths actually declined between 2004 and 2006," the WHO said in a statement.
"The reduction is primarily due to changes in the method for estimating the number of cases outside Africa. The method for Africa remained the same," its report explained.
The WHO's global death toll from the disease, which is especially deadly for infants, children, and pregnant women, was nearly steady in the new report. It estimated 881,000 died from malaria in 2006, compared to "more than 1 million" previously.
"The global burden of malaria remains enormous," it said.
Reuters