It seems African countries are least affected by Corona Virus in spite of having less facilities compared to China,Iran & Germany.How come?

Two possibilities.

1. Less travel by people because they are poorer.

2. A far more subtle approach is different ethnicities of the world may have different resistance levels to a given virus.

Mongoloids (Chinese) and Caucasoids(Europeans/white) may only have a low resistance to this virus. However, Negroids(Africans) may have a higher resistance level. This may be because of different genetic make-up/genes. We just don't know.

Less people traveling to those countries.

They have adopted the Trumpian "if you don't test for it you won't find it" theory. Africa because they can't afford it. Trump through monumental ignorance and stupidity.

they get VERY FEW Chinese visitors .......................

Because no one goes there on a regular basis