I'm not quite sure what you're asking and I am not going to ask you to elaborate to appear as though I am being intelligent by asking questions because this conversation is not in real-time, I may not come back here for a few days. No it is not a random coincidence that the diseases you mention came from adjacent regions...it is specifically because those regions are tropical, and have a lot of disease vectors. Read up on, "tropical disease," and how vectors play into disease. Disease comes from random mutations, and when you have a high density of random mutations and things that can carry those new diseases around, you have a higher likelihood of any given species (e.g. humans, for example), contracting a novel disease. While humans originated in the same area as where those diseases are coming from relative to the size of the earth, humans came from a completely geographically distinct and isolated area, e.g. the Rift Valley vs the Congo Basin which is separated by the Mitumba mountain range and has a completely different ecological character. Congo = Jungle. Rift Valley = Savannah. Much more vectors and biological diversity in Congo than Rift Valley.

Edit: For those who are saying, "We are dumb to eat apes." You are actually dumb for not realizing why people would eat apes, because you have a wide range of information gathering resources at your disposal to understand why people would eat apes, but you are not using it, while most of the people who eat apes totally lack information. They are ignorant, while you are actually just dumb.