Saturday, October 9, 2010

Learning to Live With Malaria

It’s technically straightforward to eliminate malaria from an area. At least in theory. You reduce the ability of mosquitoes to bite people, treat every sick victim with curative drugs and prevent any infected person from bringing new parasites into the area. Keep working outwards from your area, and eventually there will be no more malaria.

But what if there’s a secret reservoir of pathogens in the bodies of wild animals, unreachable by medical interventions — as there is in yellow fever, cholera, and influenza, diseases from which humankind can never hope to be completely free?

In results reported in the Jan. 19 “Proceedings of National Academy of Sciences,” a team of malariologists from France and Gabon have found just that. Using new methods of tracking malaria parasites, by subjecting samples of urine and feces to PCR analysis, the scientists found genetic traces of the most malignant malaria parasite — Plasmodium falciparum, presumed since the 1930s to be an exclusively human pathogen — inside the bodies of gorillas from Cameroon and Gabon.

There is also evidence from Vietnam and Malaysia that malaria parasites previously considered exclusive to monkeys can often be found utilizing human blood.

These discoveries of a possible wild reservoir for humankind’s most malignant malaria, some 130 years after the discovery of the malaria parasite, could mean that it will be impossible to eradicate malaria. When scientists discovered in the 1930s that monkeys carried yellow fever virus, they were forced to abandon hopes for eradicating yellow fever.

The realization will change anti-malaria work radically. Ever since the British army surgeon Ronald Ross and the Italian zoologist Giovanni Grassi discovered early in the 20th century that mosquitoes transmitted malaria parasites, dreams of eradicating malaria have tantalized governments, public health leaders and philanthropists.

In 2007, Bill and Melinda Gates — whose foundation now sets the agenda in global health — announced that they intended to end malaria, an ambition that both the interagency Roll Back Malaria Partnership and the World Health Organization affirmed. Funds for the job have zoomed from $100 million a year in 1998 to nearly $2 billion by the end of 2009.

The Gates Foundation has given vaccine researchers $150 million since the late 1990s. There are dozens of experimental malaria vaccines in labs across the globe, with the most clinically advanced, Mosquirix, appearing to reduce the incidence of illness from malaria by 65 percent.

Oil companies such as ExxonMobil, plagued by malaria in West Africa, have bankrolled genomics research at Western universities in search of new drugs. Even venture capitalists such as the former Microsoft executive Nathan Myhrvold have joined in. He showed his laser mosquito-zapping system at a highly publicized lecture in February.

All hope to find a simple, permanent cure.

The new findings, however, challenge this dream. That is because eradicating a disease is, in several important respects, a goal diametrically opposed to controlling one.

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