The origin of HIV/AIDS

Human immunodeficiency virus, or HIV, belongs to a family of organisms known as retroviruses, which insert their own genetic code into cells for the purpose of replication. When a person contracts the virus, it enters the host's cells, especially CD4 T-cells, which help to fight disease and whose presence can signal the development of HIV/AIDS in the patient.

Studies show that HIV may have jumped from apes to humans as long ago as the late 1800s, and a chimpanzee in West Africa is regarded as the initial source of human infection.

Scientists believe the chimp had simian immunodeficiency virus, which was most likely transmitted to humans and mutated into HIV through infected blood when the animal was hunted and eaten.