In 1981, CDC received reports from Los Angles of five cases who had rare Kaposi carcinoma and severe immune suppression. These cases were thoroughly investigated because the disease clustered in a unique population—among those men who had sex with men. The initial interest was to examine whether the unusual sexual behavior was linked to this disease. It was suspected that a new infectious disease occurred. The virus was identified in 1986 by researchers in France and the US. Human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) have become common words since then.

Where did HIV come from? Any curious mind would ask but no one is able to answer. Most scholars now agree that this deadly virus was originated in Africa, presumably from the chimpanzees living in Cameron or Congo.

However, it is not easy to nail down the exact spot where the virus jumped from Chimpanzees to human, and even harder to figure out how the occasional crosses spread to the entire world.

When HIV was identified, researchers also speculated that the virus may be originated in Africa, as the genetic structure of HIV was similar to some viruses in monkeys. Simian immunodeficiency viruses (SIV), the brothers of HIV, are harmless in monkeys and chimpanzees. In some primate groups, the prevalence of SIV can reach 50%. A recent report has convincingly linked the major subtype of HIV, HIV 1, to the SIV in one specific primate group—a group of chimpanzees living in the Cameron. The genetic structures of the two viruses are very close, and they might separate from each other less than 100 years ago. In fact, one year after the initial discovery of AIDS patients in the US, similar cases were found in Africa. When examining the blood sample stored in 1959 from Kinshasa, Congo, researchers have also detected the first HIV carrier. It appears that HIV has been circulating in the locals for years before spreading to the world.

How could the virus in Chimpanzees jump to human?

There is one theory hypothesized by a journalist, Edward Hooper. He speculated that HIV jumped from chimpanzees to human by an accident in polio vaccination in the 1960s. One type of oral polio vaccine (OPV) used in an experiment then was developed by a company which used monkey kidney cells to harvest polio virus. It is possible that this live virus vaccine was contaminated by HIV. Unfortunately, despite the publicity and the support from some African celebrities, this theory has very little factual support. The company who developed the polio virus denied having used chimpanzee’s kidney cells. Researchers also believe that HIV cannot transmit to human and between humans through oral pathway. Besides, there are other strains of HIVs circulating. How could one contamination generate several HIVs? Finally, there is no hard evidence suggesting that the old polio vaccine was contaminated by HIV.

Thus, it is more likely that the SIV jumped into human accidentally and mutated to be infectious in human. Considering this scenario: In the 1930s when thousands of Cameroonians fled into jungles to avoid the rail road work, they hunted monkeys and chimpanzees for foods. Sometimes the chimpanzee bloods got into hunters’ bloods through wounds during dissecting the chimpanzees or fighting with them. Some unlucky people got infected by SIV, and then they transmitted the mutated virus (HIV) to other people. After several years, some of those HIV carriers went to big cities such as Kinshasa to start new lives. From there, different strains of HIVs got mixed and some further mutated into more deadly ones, and launched to the whole world.

The origin of HIV may be a myth and need more research. However, the most urgent task now is to education the public that HIV can be prevented by ways such as safe sex and not sharing syringes. The government should allocate more resource to help the poor so that they won’t have to sell their bloods in crappy hospitals and clinics. Fighting against HIV is more a social problem rather than a medical problem. The society, not the public health organizations, needs to do more.