Plasmodium vivax malaria in Duffy-negative individuals from Ethiopia

This study was conducted to estimate the prevalence of Plasmodium vivax and polymorphisms in the Duffy antigen receptor for chemokines (DARC) gene in patients with suspected malaria from eastern (Harar) and southwestern (Jimma) Ethiopia. Plasmodium presence and species was assessed by microscopy in 1304 and 627 febrile patients in Harar and Jimma, respectively, during OctoberNovember 2009. All microscopy-positive samples were confirmed by PCR. DARC gene polymorphisms were identified by DNA sequencing. Plasmodium vivax was the dominant species in Harar (74/98, 76) and P. falciparum was more common in Jimma (70/107, 65). We found 17/98 (17) and 24/107 (22) homozygous Duffy-negative patients in Harar and Jimma, respectively. Unexpectedly, three Duffy-negative patients from Harar had P. vivax malaria. This study documents the emergence of P. vivax malaria in Duffy-negative individuals in Ethiopia. The Duffy-negative blood group does not appear to provide absolute protection against P. vivax infection in this region.