Negative Duffy defense strategy: resistance mechanisms against vivax malaria

The Duffy blood type system consists of three alleles: FY*A, FY*B, and FYnull, leading to four phenotypes: Fy (a+b+), Fy (a–b+), Fy (a+b–), and Fy (a–b–). The Fy (a–b–) phenotype, which lacks both FY*A and FY*B alleles and other Duffy antigens, is predominantly found in native African populations and is associated with resistance to vivax malaria infection. Despite this, rare cases of vivax malaria have been reported in individuals with the Fy (a–b–) phenotype in Papua New Guinea. An evolutionary perspective reveals that the Duffy glycoprotein (DARC) binds chemokines from both Cysteine — any amino acid — Cysteine (C-X-C) and Cysteine — Cysteine (CC) classes and interacts with the malaria parasites Plasmodium vivax and Plasmodium knowlesi. Diagnosis of vivax malaria can be confirmed using microscopic examination and Rapid Diagnostic Tests (RDTs). Treatment options including chloroquine and primaquine effectively reduce parasitemia, mitigate direct risk to the host, prevent infection, and interrupt the transmission cycle.