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The parasite that causes malaria is much older and more genetically diverse than some researchers had thought, a new analysis has revealed. The discovery could mean that it will be difficult to make drugs and vaccines to combat the disease worldwide.

Four years ago Francisco Ayala of the University of California, Irvine, suggested that the majority of Plasmodium falciparum parasites died out 3,000 - 5,000 years ago, leaving just a small, genetically homogenous population that would be poorly equipped to develop resistance to drugs or vaccines.

This appealing but controversial idea — dubbed the ‘Malaria’s Eve’ hypothesis — also raised hopes that a vaccine or drug developed against the P. falciparum from Thailand, say, would stand a good chance of working against one from Africa.

But the latest analysis published in this week’s issue of Nature — the largest survey of a section of the P. falciparum genome carried out so far — suggests that the parasite is much more genetically complex, increasing its ability to evade anti-malarial efforts.

In a related study, the malaria genome was scanned for genes that are known to cause resistance to chloroquine — a common anti-malaria drug. It was previously thought that chloroquine resistance evolved twice (in South America and Southeast Asia), but the researchers conclude that it must have evolved in Africa too.

Chloroquine resistance is still rare, but the new finding lends weight to the argument that P. falciparum is worryingly adaptable.

Link to full article, Gene screen suggests one drug won't beat parasite

Reference: Nature Science Update

See also:
Link to Nature news and views article Malaria variorum, Andrew G. Clark
Link to Nature research paper Chromosome-wide SNPs reveal an ancient origin for Plasmodium falciparum, Nature 418, 323-326 (2002)

Link to Nature research paper Genetic diversity and chloroquine selective sweeps in Plasmodium falciparum, Nature 418, 320-322 (2002)
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