A 24-year-old woman with sickle cell disease is seen in the emergency room for an acute upper respiratory tract infection. Laboratory findings reveal severe, normocytic anemia. The patient develops a rapid drop in the hemoglobin level. However, the reticulocyte count is very low (<0.1%). This finding most likely reflects which of the following conditions?
Aplastic crisis in sickle cell disease arises from the infection of red cell progenitors by parvovirus B19, which causes a transient cessation of erythropoiesis and a sudden worsening of the anemia. It is triggered by infection of erythroblasts in bone marrow with parvovirus B19.