Hematological manifestations of parvovirus B19 infection.

Primary parvovirus B19 infection usually occurs during childhood. Normal in dividuals either remain free of hematological abnormalities or develop a tr ansient and moderate impairment in bone marrow function responsible for ret iculocytopenia (without significant anemia), leukopenia, and thrombocytopen ia. In patients with inherited chronic hemolytic anemias, most notably sick le cell anemia, hereditary syherocytosis, and thalassemia, acute parvovirus B19 infection is responsible for transient erythroblastopenia manifesting as a further hemoglobin decrease that frequently requires blood transfusion therapy. The diagnosis is suggested by the low reticulocyte count and conf irmed by the detection of IgM antibody to parvovirus B19. Patients who fail to mount an adequate humoral immune response because of a congenital condi tion (congenital immune deficiencies, fetus) or an acquired disease (HIV in fection, chemotherapy, transplantation) can develop chronic erythroblastope nia. Polyvalent immunoglobulin therapy is effective in correcting the anemi a, although repeated injections are usually necessary to maintain this effe ct. Parvovirus B19 infection has also been shown to be associated with idio pathic thrombocytopenia purpura and autoimmune neutropenia of childhood. Pa rvovirus B19 has been reported to cause hemophagocytosis syndrome in normal individuals and in patients with immune deficiencies or chronic hemolysis.