A case of persistent anemia in a renal transplant recipient: association with parvovirus B19 infection.

We report an unexplained anemia that persisted for 4 months in a renal transplant patient who was receiving immunosuppression therapy that included prednisolone, tacrolimus and azathioprine. A bone marrow biopsy demonstrated pure erythroid hypoplasia and occasional giant pronormoblasts with intranuclear inclusions, characteristic of a parvovirus B19 infection. Both the serum and bone marrow cells were positive by parvovirus B19 DNA PCR. The anemia resolved 6 weeks after the administration of intravenous immunoglobulin (IVIG). Four months later, anemia redeveloped and IVIG was infused again. Hemoglobin levels were, however, still subnormal after 1 month of treatment and tacrolimus was then switched to cyclosporin A, resulting in a clear improvement. A parvovirus B19 infection should be included in the differential diagnosis of renal transplant recipients who present with anemia associated with a low reticulocyte count. Tacrolimus may possibly impair the clearance of a parvovirus B19 infection.