The parasite that causes the most severe form of malaria is circulating in gorillas, according to a new study contributed to PNAS by Academy member Francisco Ayala of the University of California, in Irvine. Scientists previously thought only humans carried this deadly form of malaria (press release).
Ayala and his team analyzed gorilla poop and found DNA evidence of Plasmodium falciparum — the malaria that causes almost all deaths from the disease — in two gorilla subspecies. They also found the parasite in blood samples taken from a wild born “pet” gorilla in Gabon. (BBC)
Chimps and gorillas were known to carry a parasite closely related to Plasmodium falciparum, called Plasmodium reichenowi, but these parasites were thought to have coevolved with their hosts over the past 5 million years or so and be unable to infect the other apes. Some of the early evidence supporting this hypothesis appears to come from a rather ghastly study in 1939, in which blood from P. reichenowi-infected chimpanzees was injected into humans, and blood from P.falciparum-infected humans was injected into chimps, resulting in neither suffering from an infection.
The new findings suggest that human malignant malaria does indeed infect gorillas, although they don’t appear to be ill, perhaps due to their long exposure to P. reichenowi. Nevertheless, mosquitoes sucking their blood may pass the parasites to the next host — and as deforestation and habitat destruction in sub-Saharan Africa barrel along, the authors point out, that host is increasingly likely to be a human.
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