Contrasting Epidemiology and Genetic Variation of <em>Plasmodium vivax</em> Infecting Duffy Negatives across Africa

Abstract

Recent studies indicated that Plasmodium vivax can infect Duffy-negative individuals, but the varied diagnostic and methodological approaches have limited our ability to characterize P. vivax across Africa. Here, we utilized a standardized approach to compare epidemiological and genetic attributes of P. vivax from Botswana, Ethiopia, and Sudan, where Duffy-positive and Duffy-negative individuals coexist. Among 1,215 febrile patients, the proportions of Duffy negativity range from 20-36% in East Africa to 84% in Southern Africa. Considerable differences were observed in P. vivax prevalence among Duffy-negative populations ranging from averaged 9.2% in Sudan to 86% in Botswana. P. vivax parasite density in Duffy-negative infections is significantly lower than in Duffy-positive infections. Phylogenetic analyses of 229 PvDBP sequences indicated that Duffy-negative P. vivax were not monophyletic but occurred in multiple well-supported clades, suggesting independent origins. Duffy-negative Africans are clearly not resistant to P. vivax and the public health significance should no longer be neglected.