A recent study has discovered why the sickle cell trait protects against malaria.
[To clarify, the sickle cell trait is present when an individual has inherited the sickle cell trait from only one parent. These people do not have sickle cell anemia, which is a painful disease, itself. When a person inherits the trait from both parents, they have the sickle cell anemia disease. ]
The study has shown that when malaria parasites invade sickle blood cells, they cannot inflict as much damage as they do when they attack normal red blood cells. When malaria infects a normal person’s blood cells, the parasites twist a protein “actin” from the blood cell’s membrane into a type of scaffolding that lets them cling to the cell and inject its own sticky proteins into the cell. Then, these infected blood cells cling to the walls of capillaries, the brain, and other organs keeping the infection in the body. These cells are stuck and cannot travel back to the spleen, which would clean up the infection.
However, blood cells with the sickle cell trait are resistant to “actin mining” which means the malaria infection cannot cling to the cells and the spleen can kill the malaria, protecting the infected individual from death.