Sickle-cell anaemia is related to malaria not to typhoid and person suffering from sickle-cell anaemia are resistant to malarial parasite as RBC of sickle-cell anaemic patients is distorted in shape that not affected by Plasmodium sp. It is known that heterozygotes , having both types of haemoglobin show resistance to malarial infection because the body targets . falciparum infected cells for destruction. In contrast, individuals homozygous for normal haemoglobin suffer high mortality rates in early childhood due to malarial infection.