What is the source of AIDS?

In Cameroon (an African country), about 100 years ago, or more precisely 1908, a hunter shot a chimpanzee with an arrow. When cleaning up the prey, I accidentally scratched myself, causing the blood of the orangutan to come into direct contact with my own blood. Just then, an unknown virus' crossed the border'. In other words, the virus was introduced from one species to another. This is how the story of AIDS begins.

The story of The Wounded Hunter is only a version, but it is considered to be the most likely scenario to explain how apes' immune deficiency was transmitted to humans and became HIV.

In particular, because scientists can track this virus, we can know exactly where it crosses the border. Like all viruses, HIV will mutate with a constant probability. Scientists can use the mutation rate to understand the history and trend of virus changes. Because HIV is similar to simian immunodeficiency virus, researchers believe that HIV should also originate from the virus carried by orangutans. By completely sampling the African orangutan population and measuring the mutation probability of the virus they found, scientists narrowed down the place where' crossing the border' occurred, which was a remote area in Cameroon in the early 20th century.

So in the following story, the injured hunter returned to the nearby town along the river and inadvertently passed it on to others through physical collision. Then the virus spread from one town to another until Leopoldville (now Kinshasa, the capital of Congo). However, in Kinshasa, due to the rapid population expansion in 1920- 1950, Belgian colonial officials repeatedly used syringes in medical activities, resulting in cross-infection of viruses. This makes the virus spread faster.

1960, Belgium abandoned the Congo colony and led the Haitian medical community in Kinshasa back to Haiti. At least one of them brought HIV back to Haiti. Then, a local clinic run by Americans collects plasma for a fee. Repeated use of needles in clinics further led to the spread of the virus in Port-au-Prince. Around 1969, some infected plasma entered the United States and was used by hospitals and clinics. Since then, the virus has spread through drug users sharing needles and sexual contact between homosexuals.

This virus, later called human immunodeficiency virus (HIV), leads to chronic viral disease (AIDS) of autoimmune deficiency syndrome. By 20 17, about 35 million people will die of AIDS. Due to medical progress and preventive measures, the average number of deaths and new infections decreased year by year after reaching the peak in 2005.