Question: Hi, I find your research really interesting and worthwhile. You said that gorillas and chimpanzees are heavily infected with malaria parasites. How do the parasites make it from the gorillas to the humans? How have the parasites adapted to being suited to humans and how do the parasites recognise human red blood cells in order to invade them?

Julian Rayner answered on 15 Mar 2011:

Hi Joe.

Thanks – I find it interesting and worthwhile too!

We honestly don’t know how the malaria parasite adapted from apes to infect humans, but the current data suggests that it only happened once, which suggests that it wasn’t easier. HIV seems to adapt more easily – it appears to have jumped from apes to humans at least four independent times, although only one of those went on to cause the AIDS epidemic.

My hypothesis is that part of the adaptation of malaria parasites involves adapting to recognise human rather than ape red blood cells, although there are other hypotheses too. Parasites recognise human red cells through proteins on the surface of the parasite, that bind specific receptors on the red cell surface. In many cases we don’t know what binds to what though, which is one thing we are trying to work out, because that way we know which interactions to target with drugs or vaccines to try to stop invasion.