Which virus is associated with aplastic anemia in patients with sickle cell anemia?

Parvovirus B19 is notably associated with aplastic anemia, particularly in patients with sickle cell anemia. This virus specifically targets erythroid progenitor cells in the bone marrow, leading to a significant reduction in red blood cell production. In sickle cell patients, who already have compromised erythropoiesis due to their underlying condition, the additional suppression of red blood cell production can precipitate an aplastic crisis.

The disease mechanism involves parvovirus B19's ability to replicate in rapidly dividing cells such as those in the bone marrow that produce red blood cells. When these erythroid progenitor cells are infected, the resultant destruction can lead to severe anemia, especially in individuals already at risk due to their hematological disorder.

While other viruses mentioned, such as HIV, Epstein-Barr virus, and cytomegalovirus, can cause various hematological issues, they are not primarily associated with the pathophysiology of aplastic anemia in the context of sickle cell disease as parvovirus B19 is. Therefore, its specific tropism for erythroid progenitors and its impact on already impaired erythropoiesis is the reason parvovirus B19 is the correct answer in this scenario.