Hematopoiesis in human malaria

This paper presents changes in the bone marrow of patients with malaria; it is based primarily on observations of bone marrows of 89 Gambian children with P. falciparum malaria and includes a review of the literature. Erythroid hyperplasia with dyserythropoiesis was found to be more common in patients with severe anemia and low grade parasitemia than in those with acute malaria. The dyserythropoietic changes are illustrated both with light photomicropraphs and with electron micrographs. The significance of the dyserythropoiesis and possible causes are discussed. Other changes in these patients with acute malaria include lymphocytosis in the bone marrow and reactive lymphocytes, monocytosis and mild neutrophilia in the peripheral blood. Giant metamyelocytes were also commonly seen in bone marrow of patients but were thought to be part of dysmyelopoiesis and not due to B12 or folate deficiency. Phagocytosis of erythrocytes, parasitized cells and nucleated cells was more commonly seen in macrophages in acute malaria, while phagocytosis of small particles such as merozoites was observed in neutrophils. Megakaryocytes were found to be increased in number in patients with acute malaria; a proportion of these cells had rounded nuclei, probably indicating accelerated platelet turnover.