Why does malaria often cause severe illness according to evolutionary medicine?

According to Darwinian medicine, the virulence of a pathogen—its ability to damage host tissues—is often shaped by natural selection to maximize the rate of its spread. While some respiratory viruses evolve to be less severe so that hosts remain mobile enough to infect others, malaria parasites follow a different evolutionary strategy.1

Malaria parasites spread more effectively when they make the host too sick to defend against mosquitoes. Because the parasite's transmission relies on the mosquito vector, the host's mobility is not a limiting factor for the parasite's spread in the same way it is for respiratory pathogens. Consequently, malaria tends to be quite virulent, as the evolutionary pressure favors high replication rates that damage the host, rather than the host's continued activity.1