ABO Blood Groups and Cholera: An Investigation of an Infectious Disease as an Agent of Natural Selection.

Abstract

In a 1949 landmark paper Haldane proposed that infectious diseases may act as agents of natural selection. Apart from the well-established link between sickle-cell anaemia and malaria, direct evidence for the selective effect of infectious disease is scarce. There is some evidence to suggest that blood group O individuals may be more susceptible than individuals from other blood groups to life-threatening cholera infections. Cholera is endemic to the Ganges River Delta in India, a region whose current population appears to represent the lowest global frequency of the 0 allele. Using a model proposed by Svanborg-Eden and Levin (1991) as the framework of investigation, this paper evaluates the evidence for cholera operating as an agent of natural selection in the Ganges River Delta. This model proposes a series of six conditions that must be met in order to accept an infectious disease-mediated selective effect. All six conditions could not be satisfied by the existing evidence, and it is therefore concluded that cholera cannot be accepted as further evidence of infectious diseases acting as agents of natural selection in human populations.