Anemia can present in children who are otherwise healthy, or who have systemic disease or a known hematologic disorder. Anemia is defined as a reduction in red blood cell (RBC) mass or blood hemoglobin concentration, resulting in reduced oxygen-carrying capacity. Anemia can present as a single (infectious such as parvovirus B19) or multiple cell line defect, including bone marrow involvement (aplastic anemia). Therefore, children who present with anemia with associated symptoms should be carefully evaluated to promptly formulate a differential diagnosis, anticipate a life-threatening condition, confirm the diagnosis, and start appropriate therapies.

An aplastic crisis is an infection caused by human parvovirus B19 transmitted through exposure to infected respiratory droplets or other viruses that including cytomegalovirus, Epstein-Barr virus, and human immuno- deficiency virus. The virus targets rapidly proliferating erythroid progenitor cells in the bone marrow and attaches to the P antigen receptor, resulting in reticulocytopenia and erythropoietic arrest. The RBC production is “turned off” for approximately 10 days. In patients with sickle cell disease, the RBCs only live for 10 to 15 days. Therefore, these patients are severely affected and will experience significant reductions in blood counts, with resulting congestive heart failure, cerebrovascular accident, and acute splenic sequestration. Confirmation of parvovirus B19 is performed with DNA testing. Patients with transient aplastic anemia or immunodeficiency will not test positive for immunoglobulin (Ig)M or IgG with the B19-specific antibody and remain contagious. Treatment includes simple blood transfusion to correct the severe anemia and prevent other organ complication or failure. After viral infection, patients will gain lifelong immunity with parvovirus B19, a one-time event for the patient.