A Mobile Ad hoc NETwork (MANET) is vulnerable to routing misbehavior, due to faulty or malicious nodes. Misbehavior detection systems are designed to remove this vulnerability. The authors' system uses the concepts of Artificial Intelligence (AI) and Human Immune System (HIS) to detect misbehavior in routing protocol. In their system once a node has been attacked it will not only detect it but also it will tell its neighbor about the attack thereby protecting the entire network against the attack. The concept is similar to what happens in the human body once they suffer from a particular disease they develop immunity against that disease.