In Africa, as anywhere in the world, travel involves risks.
Anywhere you travel, there are bad parts of town, especially in big cities, and of course the cities of Africa are no exception. But the parents of American Peace Corps volunteers worry more about their other children, the ones in U.S. cities, than about their children in Africa! Be careful, and don't do anything stupid -- but don't worry unduly.
That said, there are bandits on the roads, especially at night, so be sure to reach your destination before sunset.
It is also true that Al-Qaeda occasionally takes hostages in West Africa. But the WAP parks are a healthy distance from the parts of Mali and Niger frequented by the terrorists. Remember, distances in Africa are huge! In any case you will be safer with a guide who knows the country well and who has his own intelligence network.