Akimbo and the Snakes by Alexander Mccall Smith.

Akimbo can’t believe his luck when his father allows him to visit his uncle Peter’s snake park. And when a local village calls to report a sighting of a green mamba snake—the rarest and deadliest one of all—Akimbo hopes to help his uncle catch it for the park. But little does he expect to find himself trapped face to face with the deadliest of reptiles.