It afflicts 300 million people annually, one million of which die. The hardest hit are African children. Control of malaria is difficult due to its complex life cycle. Vaccine development is a major priority in combating malaria, but as of yet, no effective vaccine exists. The only real means of control target the mosquito.
Education is also a priority in underdeveloped regions.
On an interesting side note, sickle cell anemia is believed to have evolved in response to malaria infection since Plasmodium cannot penetrate sickle cells.