Examples of blood diseases include anemia, hemophilia and blood cancers, according to the American Society of Hematology. Leukemia, myeloma and lymphoma are common types of blood cancer. Anemia, the most common blood disease, affects millions of people and occurs when there is an insufficient amount of red blood cells or when these cells fail to function properly.
Aside from anemia, blood diseases that affect red blood cells include malaria and polycythemia vera, according to WebMD. Malaria is a blood infection from a specific mosquito bite and is prevalent in parts of Africa. Malaria can also be contracted in several tropical and sub-tropical countries. Polycythemia vera can cause blood clots in some patients, and it occurs when the body creates excess red blood cells.
Sickle cell anemia is a genetic condition that occurs in patients who have sickle-shaped red blood cells instead of normal disc-shaped cells, explains Healthline. The red blood cells of patients with sickle cell anemia have abnormal hemoglobin molecules and become curved and rigid. Unlike regular red blood cells, sickle cells are unable to carry enough oxygen to tissues and can also block normal blood flow to organs when they become stuck in a patient's blood vessels. This disease is common among African-Americans and is often inherited by children with parents who both have the condition.