The anaemia of Plasmodium vivax malaria

Abstract

Plasmodium vivax threatens nearly half the world's population and is a significant impediment to achievement of the millennium development goals. It is an important, but incompletely understood, cause of anaemia. This review synthesizes current evidence on the epidemiology, pathogenesis, treatment and consequences of vivax-associated anaemia. Young children are at high risk of clinically significant and potentially severe vivax-associated anaemia, particularly in countries where transmission is intense and relapses are frequent. Despite reaching lower densities than Plasmodium falciparum, Plasmodium vivax causes similar absolute reduction in red blood cell mass because it results in proportionately greater removal of uninfected red blood cells. Severe vivax anaemia is associated with substantial indirect mortality and morbidity through impaired resilience to co-morbidities, obstetric complications and requirement for blood transfusion. Anaemia can be averted by early and effective anti-malarial treatment.

Figure 1

Comparative pathogenic mechanisms of anaemia associated withP. vivaxandP. falciparummalaria (mechanisms in red font relate to vivax malaria and mechanisms in black relate to falciparum malaria). Abbreviations: RBC; red blood cell, CD35; complement receptor 1, CD55; decay accelerating factor, LDH; lactate dehydrogenase, α-HBDH; alpha-hydroxybutyrate dehydrogenase, RSP-2; ring surface protein 2, RAP-2; rhoptry-associated protein-2, EPO; erythropoietin.

Figure 2

Mean haemoglobin concentration in relation to parasitaemia in patients with syphilis treated with inducedP. vivaxinfections (98 with the St Elizabeth strain, 11 with the Chesson strain and 2 with the Korean strain). Reproduced with permission from Collins WE, et al. [73].

Figure 3

Outstanding questions on the anaemia ofPlasmodium vivaxmalaria.