The only airline offering direct service from the US is South African Air. After that you can catch any airline to Europe to it's hub and then connect to South Africa. (i.e. British Airways connecting via London, Air France via Paris, etc.)
well if i knew where you wanted to fly from i could get some prices and tell you which to fly and also i would need to know when you would want to go but since this lacks the ionformation needed i can not do that