Infections with which virus can cause aplastic anemia crises in individuals with sickle cell disease or beta-thalassemia?

• A. Hepatitis B virus
• B. Parvovirus B19
• C. Epstein-Barr virus
• D. Cytomegalovirus

Answer: (B)

Parvovirus B19 causes an aplastic crisis by temporarily shutting down erythropoiesis in the bone marrow. In people with sickle cell disease or beta-thalassemia, red cells are produced at a high rate to compensate for their short lifespan. When Parvovirus B19 infects erythroid precursors, it halts red cell production, leading to a sharp drop in reticulocytes and a sudden, severe anemia despite otherwise normal white blood cell and platelet counts. This isolated, transient suppression of the red cell line underpins the aplastic crisis seen in these conditions.

Other viruses listed can cause hepatitis or mononucleosis-like illness and cytopenias, but they do not cause the characteristic erythroid-specific aplasia that triggers an aplastic crisis in patients with chronic hemolytic anemias.