Human parvovirus-associated red cell aplasia in the absence of underlying hemolytic anemia

Human parvovirus (HPV) infection has recently been implicated as the cause of aplastic crisis in patients with hemolytic anemias such as congenital spherocytosis and sickle cell anemia. The virus causes a transient red cell aplasia which, in patients with a shortened red cell life span, is manifested as a rapid worsening of the anemia and an absence of peripheral reticulocytosis. Recovery is associated with the presence of giant pronormoblasts in the bone marrow, and several days later, a brisk peripheral reticulocytosis. In normal subjects, HPV causes erythema infectiosum (fifth disease) but is not associated with symptomatic anemia, probably because of the duration of the normal red blood cell life span. A case of HPV infection producing severe anemia in an immunocompromised patient without an underlying hemolytic anemia is presented here. Infection in this patient, a 3-year-old boy with acute lymphoblastic leukemia in remission, may have been prolonged by immunosuppression, leading over a 4-week period to a severe anemia. The immunosuppressed appear to be another group of patients at risk of developing symptomatic anemia when infected by HPV.