AIDS originated from monkeys and was transmitted to humans through a polio vaccine containing monkey blood. It has spread widely in Africa due to lack of education about protected sex and unawareness of HIV status, with 1/4 of Africa's population predicted to die from AIDS by 2010. AIDS is transmitted through unprotected sex and from mother to child, and has orphaned over 15 million children who have lost parents to the disease. Straight African-American men have the highest rates of AIDS transmission in the United States.