Prevalence, severity, and pathogeneses of anemia in visceral leishmaniasis

Anemia is a typical symptom during visceral leishmaniasis (VL). We performed a systematic analysis of the literature on anemia in VL to understand the prevalence, severity, and possible mechanisms. Anemia is very common in VL patients with an overall prevalence higher than 90 %. The degree of anemia in VL is moderate to severe (hemoglobin level ∼7.5 g/dl), and the status can be recovered by treatment with antileishmanial drugs within a certain period of time. Possible pathogeneses of anemia in VL based on clinical observations included anti-RBC antibodies, dysfunction in erythropoiesis, and hemophagocytosis in the bone marrow or spleen, while hemolysis is a more likely cause than dyserythropoiesis. In hamsters with experimental VL, hemophagocytosis induced by immune complex and changes on erythrocyte membrane is speculated as the pathogenesis for anemia. In contrast, our recent study on murine VL indicated that hemophagocytosis contributes to anemia in contrast to lower contribution of anti-RBC antibodies or dysfunction in erythropoiesis. Together, hemophagocytosis is most likely associated with anemia in VL, and elucidation of the immunological mechanisms may lead to development of novel interventions to manage the symptom.