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Malaria Remains Daunting Public Health Challenge

The malaria epidemic is one of the greatest public health challenges today. Despite some advances, the disease remains a major killer. A child dies of malaria every 30 seconds, most of them in Africa.

The American Association for the Advancement of Science (AAAS) has been holding a series of forums here in Washington on what they call "global challenges," and as we hear from VOA's Art Chimes, this week they focused on the challenge of "solving the malaria epidemic."

Science journalist Joe Palca, who moderated the event, noted that 15 years ago, the disease got little attention in the American press.

By contrast, a database search of just three major U.S. papers in the past three months turned up 120 mentions of malaria.

"Now, that's not to say that each one of those was a major take-out kind of story, but I think that, at least to me, represents the difference between now and 15 years ago – or at least in a crude way I think it does – and maybe that will help explain why people are actually talking about eradicating malaria now."

Completely eradicating malaria – like smallpox was eliminated in the 1970s – is theoretically possible, but for several reasons it's a much more challenging goal.

For one, says Ripley Ballou of the Bill and Melinda Gates Foundation, there is not just one malaria parasite.

"There are two predominant species that cause the vast majority of infections that afflict humans – Plasmodium falciparum and Plasmodium vivax, and they are very different parasites. And a tool, a vaccine for one will not work for the other. They have different treatment regimens that are required. And the reality is, we do not have those tools today, and that's one of the big areas of ours and others' science investments."

Also, the life cycle of malaria is complex. That's good, because the chain can be broken anywhere as the parasite moves from mosquito to human. You can kill mosquitoes with insecticide or stop them from biting, for example with bed nets. But as Ballou points out, efforts at eradication have ultimately failed because it's hard to get it right.

"And during this process, the mosquito became resistant to the insecticides, the parasite became resistant to the drugs, and the resources that were brought to bear in the eradication program were not sustainable," Ballou explained. "And I think the combination of those three things led to the failure [of the eradication effort] and then the sense that it was hopeless."

The AAAS forum also included Steven Phillips, medical director for oil company ExxonMobil. Africa is a major oil-producing region, and Phillips notes that the company has some 4,000 employees there. "And a quick-and-dirty risk assessment showed, surprisingly, that malaria was the number one risk faced by our employees."

Dr. Phillips says that in Africa, an estimated 60 to 80 percent of all malaria cases are not treated by a doctor or other health professional. And many people – children, usually – are getting malaria drugs even though they don't have malaria, because the disease is hard to diagnose. Phillips says it's counterproductive to use malaria drugs except to treat malaria.

"Otherwise you're going to wind up treating people that don't have malaria with drugs that are going to not only breed resistance, but you're not going to treat the real problem. And so one of the reasons that one out of five children in Africa do not reach the age of five is because, when they have a fever, they either go undiagnosed or presumptively treated for something that they actually don't have."

That means a correct diagnosis is important. Traditionally, that involves a trained laboratory worker examining a blood sample under a microscope. An alternative, rapid diagnosis test has been developed, costing less than a dollar. Phillips describes it as being something like a home pregnancy kit.

"There's a little finger stick and a drop of blood that's put on to a strip, and then there's a colorimetric assay that changes colors that's pretty easy to read."

Some experts say the rapid diagnosis test isn't as good as the traditional, microscope-based diagnosis, and Phillips says the World Health Organization isn't convinced yet, either. That has limited the test's widespread deployment.

One strategy that has proved to be effective is insecticide-treated bed nets. Steven Phillips says his company got directly involved in a novel program to distribute the bed nets in four countries where ExxonMobil operates a total of 2,000 service stations.

"A pregnant mother would go to an antenatal clinic. She'd be given a voucher that would give about two-thirds off of a long-lasting bed net. She would then present that voucher to a local service station, and she would have a reliable supply – along with health education materials – from an Exxon service station."

The battle against malaria is important because the stakes are so high, as Ripley Ballou of the Gates Foundation points out.

"Five hundred million people around the world are infected with malaria every year, and somewhere between one and three million deaths [occur], most of these in children under the age of five. There are places where it has been eliminated, but not very many of them, so we really are talking about a global disease."