[Jedi Master Pikachu]

'Indigenous' populations for the maps.

link.

[CutePuppy]

I don't know if this research was proportional, i.e. took into account the percentage of infected (with severe cases or complications) relative to their blood type. Any decent research would, obviously, use the correlation of percentage relative to its blood type.

Research was done mostly in Mali and Kenya - per your maps, it was in the areas / continent with 70 to 90 percent of population with Type O. It just might explain why malaria did not wipe out more of a population of Africa, while being a serious problem there, since they didn't widely use DDT in Kenya or Mali, as far as I know (at least not until recently).

It also might help explain the postulate by VOA in post #4.

From Malaria Site, here are the maps of the risk of malaria for North/Central and South Americas, where blood Type 0 is predominant (90-100%) :

Malaria risk in North and Central America

Malaria risk in South America