There are several different strains, with different lethality. Also, in Africa the disease has been endemic long enough that the population has developed resist

There are several different strains, with different lethality. Also, in Africa the disease has been endemic long enough that the population has developed resistance. Malaria is much more dangerous to naive hosts, hence the high mortality rate amongst caucasians in Africa, described as the "White Man's Grave" in the 19th century. There has also been some research done on the burden to economic productivity from chronic malaria, which is quite significant. Malaria is also a contributor to higher infant and childhood mortality in endemic regions: you get the disease as a child and it either kills you or your immune system learns how to keep the chronic disease in check.