Human: When was the disease called ‘Aids’ first discovered? Assistant: 
Aids was first described in 1981 by a team of scientists led by Robert Gallo. They were studying a rare type of cancer called Kaposi's sarcoma, which is a cancer of the blood vessels. They found that the cancer cells were infected with a virus that was previously unknown. This virus was later named HIV, which stands for human immunodeficiency virus.