I have spent over fifty years in the African bush and have only felt nervous about a snake a handful of times. Nervous enough to kill one only once, a small spitting cobra resident by a house with small children. It is sobering to look down and see a six foot puff adder at your feet, more so if your foot is coming down on it. Or to find a cobra in your tent or house, but I have yet to encounter an aggressive snake or one that didn't just want to get away.