 Malaria is a disease that affects many people in the country of Mali and other parts of Africa. It is caused by germs that are spread by mosquito bites. Malaria may be mild, but can also be serious or can lead to death if not diagnosed and treated promptly. Children younger than 5 years and pregnant women are at highest risk of malaria. Researchers want to better understand how malaria infection suppresses the immune system. They want to compare a group of adults who receive antimalarial treatment to a group that does not receive it. 