Whether it is sanitary conditions or other scientific equipment, it is relatively late, or even not at all. In addition, people's living conditions are objectively Petri dishes for indigenous people and Africans to become viruses. We must admit that the vast majority of incurable diseases spread from Africa to the world come from animals. Spread to Africans through blood, etc., spread to all parts of the world. The original HIV was caused by bacterial mutation in gorillas and then spread to humans.
In addition, the bacteria successfully overcame racial differences, and the spread among primitive apes became a patented disease of modern human beings. In fact, it is not as open-minded as some people think on the Internet. Lack of contact between blacks and African gorillas will lead to AIDS. Actually, it's not. The initial spread of AIDS was through blood, and local Africans died of blood.
I think, when the blood of an orangutan is a magical medicine of nature, many times it will collect blood after killing the gorilla. Of course, according to the indigenous laws of African tribes, this kind of blood can cure their diseases. However, this is also because such a mutated virus has entered the human body through the blood. The African continent is excluded from the relatively backward areas outside Antarctica. The humid climate tide breeds bacteria, and the population sent to live in Africa is relatively primitive, paying little attention to health and other matters.