<prompt> Person having heterozygous sickle cell trait is protected from infection of -Plasmodium falciparumP.vivaxPneumococcusSalmonella  <response>: Ans. a Plasmodium falciparumRef: Robbins 9thpg 635-636; 8thpg 645-646; Wintrobes 12thpg 1038Person having heterozygous sickle cell trait is protected from infection of Plasmodium falciparum Mechanism by which patients with sickle cell trait are protected against Malaria:Preferential sickling of parasitized cells has been seen in the blood of children with sickle cell trait malaria.Selective removal of sickled cells from the circulation probably reduces the degree of parasitemia and substantially limits the infectious process. 