Contrasting Epidemiology and Genetic Variation of Plasmodium vivax Infecting Duffy Negatives across Africa

Recent studies indicated that Plasmodium vivax can infect Duffy-negative individuals, but the varied diagnostic and methodological approaches have limited our ability to characterize P. vivax across Africa. Here, we utilized a standardized approach to compare epidemiological and genetic attributes of P. vivax from Botswana, Ethiopia, and Sudan, where Duffy-positive and Duffy-negative individuals coexist. Among 1,215 febrile patients, the proportions of Duffy negativity range from 20-36% in East Africa to 84% in Southern Africa. Considerable differences were observed in P. vivax prevalence among Duffy-negative populations ranging from averaged 9.2% in Sudan to 86% in Botswana. P. vivax parasite density in Duffy-negative infections is significantly lower than in Duffy-positive infections. Phylogenetic analyses of 229 PvDBP sequences indicated that Duffy-negative P. vivax were not monophyletic but occurred in multiple well-supported clades, suggesting independent origins. Duffy-negative Africans are clearly not resistant to P. vivax and the public health significance should no longer be neglected.

The profile of erythrocyte enlargement due to imported cases of Plasmodium vivax infection: its impact to the patient and the community

Background: Imported cases of malarial vivax also induce erythrocyte enlargement. The size of enlargement depend on the size of the parasite inside the cells. The aim of the study was to examine 20 slides of positive malaria vivax and seek for erythrocyte infected malaria and measure the size of enlarged cells and its shape. As a comparison, a number of normal erythrocyte also evaluated for its size and shape.Methods: This simple cross sectional design of microscope based study was conducted in Parasitology lab, Faculty of Medicine, Universitas Kristen Indonesia, Jakarta-Indonesia, from January to June of 2019. All data collected and further processed using SPSS™.Results: A total number of 982 erythrocyte infected with P. vivax were examined individually. Those number consist of 243 immature trophozoite, 231 mature trophozoite, 251 micro-gametocyte, and 257 macrogametocyte. As a comparison also being examined 70 normal erythrocyte. Each erythrocyte infected with malaria vivax parasite enlarge to some extent, had irregular shape and the size varied based on the stage of the parasite inside the cells.Discussion: This enlarged erythrocyte is prone to cell sequestration and lysis, a condition that leads to anemia. Anemia affect not just the host but also the community. Proper management of malaria will reduce the burden to the community.Conclusions: Enlarged infected erythrocyte due to malaria vivax can cause anemia with effect to the host and also to the community.