Plasmodium vivax malaria is a neglected tropical disease, despite being more geographically widespread than any other form of malaria. P. vivax was previously thought to be rare or absent in Africa because people of African descent often lack the Duffy blood group antigen, known as the Duffy antigen-chemokine receptor (DARC). DARC is a glycoprotein on the surface of red blood cells (RBCs) that allows P. vivax to bind and invade human erythrocytes. The documentation of P. vivax infections in different parts of Africa where Duffy-negative individuals are predominant suggested that there are alternative pathways for P. vivax to invade human erythrocytes that remain elusive. Duffy-negative individuals may be just as fit as Duffy-positive individuals and are no longer resistant to P. vivax malaria. The genetic characteristics and erythrocyte invasion mechanisms of P. vivax in Duffy-negative infections are largely unknown due to the less frequent occurrence in Africa and the complicated biology of P. vivax. There is evidence of an alternative Duffy-independent pathway through utilization of reticulocyte binding proteins (RBPs), merozoite surface proteins (MSPs), tryptophan rich antigens (TRAg), but they remain poorly characterized due to a lack of reliable in vitro methodology. This dissertation research aims to examine the genetic, transcriptomic, and transmission features of East African P. vivax and identify candidate ligands for erythrocyte invasion through comparative transcriptomics of major surface protein genes. Our group has shown no clear genetic differentiation in P. vivax between the two Duffy groups, indicating between-host transmission. Furthermore, we found P. vivax from Ethiopia and Sudan showed similar genetic clusters, except samples from Khartoum, possibly due to distance and road density that inhibited parasite gene flow. Lastly, our group was able to characterize the expression levels of 4,404 gene transcripts belonging to 12 functional groups. We closely examined 43 erythrocyte binding gene candidates in the Ethiopia isolates and compared with four Cambodian and two Brazilian P. vivax published transcriptomes. Overall, there were 10-26% differences in the gene expression profile amongst the continental isolates, with the Ethiopian and Cambodian P. vivax being most similar. Majority of the gene transcripts involved in protein transportation, host interaction, and resistance were upregulated in the Ethiopian isolates. Transcripts involved in host-interactions were differentially expressed across the three continental isolates. For instance, PvDBP1 and PvEBP/DBP2 were highly expressed in the Cambodian but not the Brazilian and Ethiopian isolates. PvRBP2a and PvRBP2b showed higher expression in the Ethiopian and Cambodian isolates than the Brazilian ones. In the Ethiopian schizonts, PvRBP2a and PvRBP3 expressed six-fold higher than PvDBP1 and 60-fold higher than PvEBP/DBP2. Other invasion genes including PvRBP1a, PvMSP3.8, PvMSP3.9, PvTRAG2, PvTRAG14, and PvTRAG22 also showed relatively high expression. We also found that PVP01_1403000 from female and PVP01_1208000 from male gametocytes were highly expressed consistently across all isolates compared to Pvs25, the current industry standard for gametocyte detection. Together, these data indicate the Duffy negative P. vivax originated from Duffy positive individuals and transmission may occur between both phenotypes. We also provide evidence of a Duffy-independent invasion mechanism by select PvRBP, PvRBP, and PvTRAg genes. Lastly, our data provide a reliable method for detecting sub-microscopic P. vivax gametocytes through male and female gametocyte detection. The data presented is critical for understanding P. vivax infection, transmission, and provide the first evidence for alternative invasion ligands that may be ideal targets for pharmaceutical intervention.