Why the people having sickle cell anaemia disorder do not suffer from malaria?

People with sickle cell anemia have RBC's which become clumped and the shape of the cells is arched. These cells last on an average for normally 15 as compared to an average life span of 120 days. The altered morphological shape and protein structure is not conducive for the Plasmodium species to thrive. Hence infection from malaria is prevented or reduced.