Severe anemia caused by human parvovirus in a leukemia patient on maintenance chemotherapy.

A 6-year-old boy on maintenance chemotherapy for acute lymphocytic leukemia developed severe hypoplastic anemia during chemotherapy previously well tolerated. The hypoplastic episode persisted for approximately 30 days. Human parvovirus (B19), the etiologic agent of aplastic crisis in persons with underlying hemolytic syndromes, was detected in the patient's serum 25-30 days after onset of hemoglobin decrease, and B19 IgM seroconversion occurred 1 week later. The patient's hypoplastic anemia was presumably caused by prolonged B19 infection resulting from a blunted immune response. An immune response to the B19 infection and resolution of the illness were temporally associated with brief cessation of chemotherapy.