Aplastic crisis is a condition in which the bone marrow of someone with a condition such as sickle cell disease suddenly stops producing red blood cells. This causes sudden and severe anemia. The crisis is usually caused by an infection with parvovirus. This is the virus that causes fifth disease in children.

Blood transfusions might be done to treat an aplastic crisis. This means you receive healthy blood from another person. After a few days, the bone marrow usually recovers on its own, and red blood cell production returns to its usual rate.