Duffy blood groups and malaria in the Ao Nagas in Nagaland, India.

Blood samples from 324 malarial patients and 384 healthy individuals belonging to the Ao tribal community have been examined for Duffy blood group systems. The complete absence of Duffy-negative individuals among the Ao Nagas suggests that selection for resistance to vivax malaria by means of the Duffy-negative phenotype has not been available in the southeast Asian regions including the Ao Nagas.