The considerable variation in malaria symptoms seen between patients can be predicted from the parasite's expression of certain genes and the response of the host's red blood cells to infection.

Red blood cells infected by the malaria parasite Plasmodium falciparum often stick to uninfected ones in a process called rosetting. Peter Bull and his co-workers at the Kenya Medical Research Institute–Wellcome Trust Research Programme in Kilifi studied parasites isolated from 131 infected children and found that patients with high levels of rosetting tended to have breathing difficulties. Children infected with parasites that did not exhibit high rosetting but expressed high levels of a particular subset of 'var' genes were more likely to exhibit impaired consciousness or coma. Var genes encode proteins that sit on the surface of infected red blood cells and specific subsets have previously been linked to severe malaria.

The findings could help to guide treatment decisions or lead to new therapies.

Sci. Transl. Med. 4, 129ra45 (2012)