Rapid Fire Presentation 8th International Conference on Plasmodium vivax Research 2022

Plasmodium vivax infected Duffy-negative individuals exhibit low asexual parasitaemia and remain undetected silent reservoirs: implication on malaria elimination (#202)

Lemu Golassa 1 , Andargie Abate 1 , Isabelle Bouyssou 2 , Didier Menard 2
  1. AAU, 1Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia, Addis Ababa, PLEASE SELECT STATE, Ethiopia
  2. Malaria Genetics and Resistance Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France, Addis Ababa, PLEASE SELECT STATE, Ethiopia

Introduction:

The invasion of reticulocytes by P. vivax requires the Duffy blood group antigen receptor for chemokines (DARC) for red blood cells invasion. However, the detection of P. vivax infection among Duffy negative individuals in Africa has challenged the established dogma of the associations between Duffy antigen and P.vivax invasion of reticulocytes. The human host-P.vivax relationship has brought new insights in the impact of Duffy polymorphisms on the epidemiology of malaria.The objective of this study was to determine the prevalence of P.vivax among Duffy-negative and Duffy-positive individuals; and to compare parasite density in those patients. 

Methods:

Identification of Plasmodium species was performed by microscopic examination on field sites and by real time PCR in the laboratory. Genotyping of Duffy antigens was followed by DNA sequencing to determine its polymorphisms in a total of 138 P.vivax infected samples.

Results:

The proportion of Duffy-negative among P. vivax infected patients was 2.9% (4/138) with FY*B/FY*BESand FY*A/FY*BES genotypes being the common variants. However, FY*BES/FY*X genotype was only seen in two P. vivax-infected patients. Low P. vivax parasitemia was counted in individuals with FY*BES/FY*BESand FY*BES/FY*X genotypes.

Conclusion:

Although P.vivax infect Duffy-negative individuals, polymorphisms of Duffy antigens have effect on asexual parasitemia. Patients with Duffy-negative had low density parasitaemia as compared to those with Duffy-positives. Infection in Duffy-negatives, remain undetected by the commonly used malaria diagnostic tools (microscopy and Rapid diagnostic tests) putting them as the silent reservoirs in fueling onward malaria transmission. This unquestionably affect the elimination efforts.