Cairo to Cape Town - big talk

ok, I'll bite, I've worked extensively in the countries you've referred to as "Black Africa" - which I think is not a good name for it in the slightest.

There are animals that will kill you, the great mammals like lions and elephants that are not only present in the nature reserves but also reptiles and insects that are plenty

Yes, maybe if you camp in the middle of a wildlife reserve, whilst cooking several steaks over your camp fire. If not then you have no need to worry.

Malaria and other parasites you haven’t even dreamt about that will invade you an make you feel sick, weak for weeks

Malarial prophylactics have existed for years. Atovaquone tablets are cheap, work well, and have no side effects if you make a basic level of effort.

There are huge stretches of land with little or no civilization where your fate may depend on the strangers good will

This is just pure rubbish. It's an inhabited continent. You're not going to Antarctica.

Some people lay their eyes on you without a word or any expression on their face, god knows what’s going on through their head. There are groups of junkies and alcohol addicts like nowhere in the world, places so dark you’d be rethinking your plan for days after seeing it. There is poverty, sickness and trash.

Let me guess, you have read Heart of Darkness recently.
Many of the nations in the area you have referred to are developing countries, and so they might not look the same as Europe. I can tell you LA has as many problems with "junkies and alcohol addicts" as some of the poorest neighbourhoods on the African continent I've travelled through.