Contrasting epidemiology and genetic variation of Plasmodium vivax infecting Duffy-negative individuals 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 spread into areas of high Duffy negativity across Africa. Our study compared epidemiological and genetic features of P. vivax between African regions. Methods: A standardized approach was used to identify and quantify P. vivax from Botswana, Ethiopia, and Sudan, where Duffy-positive and Duffy-negative individuals coexist. The study involved sequencing the Duffy binding protein (DBP) gene and inferring genetic relationships among P. vivax populations across Africa. Results: Among 1215 febrile patients, the proportions of Duffy negativity ranged from 20-36% in East Africa to 84% in southern Africa. Average P. vivax prevalence among Duffy-negative populations ranged from 9.2% in Sudan to 86% in Botswana. Parasite density in Duffy-negative infections was significantly lower than in Duffy-positive infections. P. vivax in Duffy-negative populations were not monophyletic, with P. vivax in Duffy-negative and Duffy-positive populations sharing similar DBP haplotypes and occurring in multiple, well-supported clades. Conclusions: Duffy-negative Africans are not resistant to P. vivax, and the public health significance of this should not be neglected. Our study highlights the need for a standardized approach and more resources/ training directed towards the diagnosis of vivax malaria in Africa. (c) 2021 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-ncnd/4.0/).

Automated summary

Plasmodium vivax malaria was previously thought to be rare in Africans lacking the Duffy blood group antigen, but recent studies show that it can infect Duffy-negative individuals. The prevalence and genetic features of P. vivax vary across African regions, with higher infection rates and lower parasite densities in Duffy-negative populations. Sharing similar DBP haplotypes, Duffy-negative and Duffy-positive populations do not show monophyletic patterns, indicating the need for standardized diagnostic approaches and resources for vivax malaria in Africa.