Plasmodia in bone marrow examinations: Case series from a hospital in Pakistan 2007-2015

Abstract Background Malaria is a life-threatening, multisystem disease caused by the protozoan plasmodia with a global incidence of approximately 212 million annually. The parasite is known to have unique and crucial interactions with various body tissues during its life cycle, notably the liver, spleen, and recent work has shown the bone marrow as reservoir of infection.Methods This study is a case series of patients in whom examination of bone marrow revealed malaria parasites. We conducted a retrospective record review of 35 malaria-positive bone marrow specimens examined at Aga Khan University Hospital (AKUH), Karachi, Pakistan, over the years 2007 to 2015. Bone marrow aspirates were collected as per International Council for Standardization in Haematology (ICSH) guidelines.Results The median age of patients was 22 years (range 1–75), and 60% (n = 21) were male. 22 patients had evidence of P. falciparum, 12 had evidence of P. vivax and 1 patient had a mixed infection. Gametocytes and trophozoites were the most common stages identified on both peripheral blood and bone marrow examinations. Indications for bone marrow examination included fever of unknown origin and the workup of cytopenias and malignancies.Conclusions The incidental finding of plasmodia in samples of bone marrow from our patients suggests the reticuloendothelial system may be regularly infected by these parasites, be it acute or chronic in character.