Like many other viruses, HIV started in animals first and was passed on to humans. In the case of HIV, the virus moved from chimpanzees and sooty mangabey monkeys to humans. 

Chimpanzees and sooty mangabey monkeys get a similar virus to HIV called SIV. There is a certain strain of this virus, called SIVcpv, that is almost identical to HIV. 

Knowing this, means we can say that HIV most likely came from monkeys and chimpanzees with SIVcpv. A small change in the SIV’s DNA meant that this virus became able to be passed from chimpanzees and monkeys to humans. 

It’s likely that the first humans caught the virus either by eating monkeys and chimpanzees that were infected with SIV or by getting their blood in wounds that they got while hunting. There are a lot of myths around the origins of HIV, with people saying that HIV was created in a lab by scientists or that it was a punishment from God - these myths are not true.

A virus is a type of ‘germ’, something that can make you sick. They are so tiny, you can’t see them without the help of a very powerful microscope. Viruses cannot survive on their own. 

They require a ‘host’ to survive and replicate. In the case of HIV, the virus can only live inside the human body. In all cases, viruses work by invading another ‘organism’ (this includes plants, animals and people – basically any living thing). 

Once they have invaded the organism they enter into a specific cell. Once inside they use the cell’s machinery to make copies of themselves. Other viruses you might have heard of are: SARS-CoV-2 - the virus that causes COVID-19, flu viruses, herpes virus or the virus that causes foot and mouth disease in cows.