Contrasting epidemiology and genetic variation of Plasmodium vivax infecting Duffy negatives across Africa

OBJECTIVES: Plasmodium vivax malaria was thought to be rare in Africans who lack the Duffy blood group antigen expression. However, recent studies indicate that P. vivax can infect Duffy-negative individuals and has penetrated into areas of high Duffy-negativity across Africa. This study compares epidemiological and genetic features of P. vivax between African regions.METHODS: We utilized a standardized approach to identify and quantify P. vivax from Botswana, Ethiopia, and Sudan, where Duffy-positive and Duffy-negative individuals coexist. We sequenced Duffy Binding Protein (DBP) gene and inferred genetic relationships among all Africa P. vivax.RESULTS: Among 1,215 febrile patients, the proportions of Duffy negativity range from 20-36% in East Africa to 84% in Southern Africa. P. vivax prevalence among Duffy-negative populations ranging from averaged 9.2% in Sudan to 86% in Botswana. Parasite density in Duffy-negative is significantly lower than in Duffy-positive infections. P. vivax in Duffy-negative populations were not monophyletic. Duffy-negative and Duffy-positive P. vivax shared similar DBP haplotypes and occurred in multiple well-supported clades.CONCLUSIONS: Duffy-negative Africans are not resistant to P. vivax and the public health significance should not be neglected. This study highlights need for standardized approach and more resources/training to diagnosis of vivax malaria in Africa.