Genetic variation in the Duffy blood group among vivax malaria patients and its impact on disease susceptibility

Plasmodium vivax is a widely distributed human malaria parasite in Ethiopia. Known for its ability to form hypnozoites and early gametocytogenesis, it promotes transmission and challenges global elimination efforts. The red blood cell reticulocyte stage is the primary target, and entry is facilitated primarily by the interaction between the Duffy-binding protein (PvDBP) and the Duffy Antigen Receptor for Chemokines (DARC). This study aimed to evaluate genetic variation in the Duffy blood group among P. vivax malaria patients and its effect on illness susceptibility. A facility-based cross-sectional study was carried out between January and June 2024 at four sites, including Arba Minch General Hospital, Dil Fana Primary Hospital, Shecha Health Center, and Weze Health Center in Arba Minch. Molecular screening was performed via SYBR Green qPCR, and Duffy genotyping via a TaqMan-based qPCR assay for 485 microscopy-confirmed P. vivax-infected samples. Demographic and clinical data were stored on an open data kit mobile application and analyzed via SPSS. Among the 485 samples, 93.8% were mono-P. vivax infections, whereas the remaining 6.2% were mixed P. vivax and P. falciparum infections. Relatively more males (58.4%) aged between 15 and 24 years participated in this study. Almost all the study participants were Duffy positive, with 75.1% (364/485) being heterozygous and 24.5% (119/485) being homozygous. Two of the study participants (0.4%) were Duffy-negative individuals, and both had mixed P. vivax and P. falciparum infections. This study revealed a low prevalence of the Duffy-negative genotype, all of which presented with mixed infections characterized by low parasitemia. This finding indicates that Duffy negativity is not an absolute barrier to P. vivax infection, suggesting the existence of a possible alternative invasion pathway. Further research targeting alternative invasion pathways is recommended to better understand this phenomenon.