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A new map of “the other” malaria

The malarial parasite, Plasmodium vivax, is something of a forgotten step sister to the more prevalent, more deadly Plasmodium falciparum. Global and local programmes looking to eradicate malaria may need to pay it more attention say several health experts presenting at this year’s annual meeting for the American Society for Tropical Medicine and Hygiene in Philadelphia taking place this week.

Today, in poster sessions, Peter Gething from Oxford University presented a newly updated map created by the Malaria Atlas Project and showing P. vivax’s impact around the world. “If you asked people before this map was available about vivax’s prevalence, you get 100 different answers,” says Gething.

So, the team assembled data from roughly 8,000 site-based surveys of infection rates and from this drew up maps modelling prevalence and risk. Because many of the survey results could only be found in unpublished ‘grey literature’ they had to work closely with global and local health ministries to get access to the numbers.

The risk of contracting this disease is extremely low throughout most of Africa, where P. falciparum is rampant and a form of genetic resistance to vivax known as Duffy negativity is widespread. But P. vivax is extremely widespread, putting nearly 130 million people at risk in Indonesia alone – more than half the population according to a map of that country presented by Iqbal Elyazar of the Eijkman-Oxford Clinical Research Unit in Jakarta, Indonesia.

“The headline for us,” says Gething, “is in terms of the elimination agenda.” The idea has been that P. vivax is a benign, less common form of malaria than its more dangerous sibling P. falciparum, which attracts upwards of 97% of the funding in terms of research and control* a far greater share of research-and-development investment. But differences in P. vivax’s life cycle and the mosquito based vectors that transmit it could make forgetting about it a serious problem.

Image: Malaria Atlas Project

* Update 12/03/2012: The 97% figure previously listed was inaccurate. According to a PATH report from last year, P. vivax was the specified target for roughly 3% of R&D funding between 2007 and 2009. Roughly 45% went to P. falciparum and more than 50% did not report the species of malaria. I regret the error and thank Austin Walker of Northwestern University for questioning my source and pointing out the error.


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