Discover Data

By Kathy A. Svitil|Monday, June 06, 2005

In the United States you have as much of a chance of contracting malaria as having a meteorite drop on your head. In other parts of the world, however, malaria is a scourge, and it’s getting worse.

How much worse is in dispute. The World Health Organization and a team of leading tropical disease specialists are at odds over the dimensions of the problem. WHO says the number of cases could be as high as 400 million. But Bob Snow of the University of Oxford in England and his colleagues say the number should be higher, that 515 million people are infected with the mosquito-borne Plasmodium falciparum parasite each year. They base their assessment on more than 80 studies from around the world that incorporated house-by-house surveys of active cases.

Both groups put the bulk of infections in Africa, but Snow and his colleagues say the number outside Africa is 200 percent higher than WHO found. Snow says WHO’s numbers are lower because the agency relies on data from clinics, which “grossly underestimates the burden of malaria,” especially in countries like India and Bangladesh, where not everyone seeks treatment in a clinic. WHO epidemiologist Bernard Nahlen argues that precise figures are impossible to find and that Snow’s range—298 million to 659 million cases—isn’t significantly different from WHO’s.

Both sides agree that the situation is terrible—and preventable. “We know what to do,” Snow says. “We know that giving insecticide-treated bed nets to a household will protect young children, reducing their susceptibility by 50 percent and their overall chances of dying by 16 to 17 percent. And it only costs four dollars.” People who do get the disease can be treated with inexpensive combination drug therapies. “To a large extent, whether it is 400 million cases or 600 million cases does not matter,” Nahlen says. “For a disease that is to a large extent preventable and certainly eminently treatable, it should be unacceptable for the burden to be that great.”

Battle of the numbers

WHO: 270 – 400 million
New estimate: 298 – 659 million

In Africa
WHO: 200 – 297 million
New estimate: 216 – 374 million

In Southeast Asia
WHO: 52 – 77 million
New estimate: 66 – 224 million

In the Western Pacific
WHO: 9 – 13 million
New estimate: 9 – 26 million

In the Americas
WHO: 3 – 4 million
New estimate: 2 – 8 million

Eastern Mediterranean
WHO: 6 – 9 million
New estimate: 5 – 25 million

WHO: 0
New estimate: .4 - .9 million

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