451 million clinical cases of malaria worldwide in 2007: Experts

A new study concludes that there were an estimated 451 million clinical cases of Plasmodium falciparum malaria worldwide in 2007.

Global clinical burden of malaria (how many people become ill because of malaria and where they live) is required to direct resources where it will have most impact. However, using surveillance date in places where malaria is endemic diagnosis is often inaccurate and national reporting is incomplete.

In the current study, researchers use a 'cartographic' method that incorporates a map of malaria risk with statistical techniques, overcoming the disadvantages of surveillance data. The study reveals that more than half of the estimated burden, and its associated uncertainty, was contributed by India, Nigeria, the Democratic Republic of Congo and Myanmar (Burma).

"The uncertainty in our knowledge of the true malaria burden in only four countries confounds our ability to assess progress in relation to international development targets at the global level. It's clear that we urgently need an increased focus on reliably enumerating the clinical burden of malaria in these nations," said Simon Hay from the Department of Zoology at the University of Oxford.

He added, "The divergence in our estimates and those of the World Health Organization is greatest in Asia and acute in India. We have sought to explore on a country by country basis how these differences arise, the relative uncertainty in the alternative burden estimation approaches and the potential insights that could be gained by hybridising the two".

The study is published this week in PLoS Medicine.