Plasmodium vivax infection in Duffy-negative populations in Sudan: a systematic review and meta-analysis of host–parasite genetic adaptation

BACKGROUND: Sudan is one of the few African countries reporting increasing Plasmodium vivax infections despite the high prevalence of the Duffy-negative phenotype, historically considered protective against this parasite. Emerging molecular evidence challenges this paradigm. The objective of this systematic review and meta-analysis was to synthesize evidence on the prevalence and geographic distribution of P. vivax infection, Duffy antigen polymorphisms, parasite genetic adaptations, and diagnostic limitations in Sudan. METHODS: statistic, while publication bias was evaluated using funnel plots and Egger's regression test. RESULTS: = 56%). Substantial genetic diversity was observed in the P. vivax Duffy Binding Protein (PvDBP), including multiple haplotypes and both Malagasy-type and Cambodian-type gene duplications. Most studies were assessed as having low to moderate risk of bias, and funnel plot inspection did not suggest substantial publication bias, although interpretation is limited by the small number of studies. CONCLUSIONS: This systematic review and meta-analysis provide evidence that P. vivax infection occurs among Duffy-negative individuals in Sudan, challenging the long-standing assumption of complete Duffy-mediated protection. The observed parasite genetic diversity highlights adaptive mechanisms that may facilitate infection in Duffy-negative hosts. Strengthening molecular surveillance and integrating host-parasite genomic data into national malaria control programs will be critical to inform malaria elimination strategies and vaccine development in Africa.