Interventions used to reduce mortality in non-malarial areas may be inappropriate

After the first description of sickle cell disease in a Grenadian dental student in Chicago in 1910, subsequent reports indicated that the disease was confined to people of African origin. Over the next 40 years, the clinical features were recorded in Americans, but it was not until the late 1940s that reports began to appear from Africa itself. These documented the high prevalence of the sickle cell trait throughout equatorial Africa and its geographical coincidence with the distribution of Plasmodium falciparum malaria. Studies from west, east, and central Africa showed that individuals with the sickle cell trait had a relative protection against malaria during a critical period of early childhood. This was believed to offset the loss of sickle cell genes from the high mortality of homozygotes, illustrating the concept of balanced polymorphism. Although the sickle cell trait may have a survival advantage in malarial areas, the occurrence of malaria …