pañcatvam rcchate jantur
bhunkta arabdha-karma tat
When a conditioned soul is killed by snakes, thieves, fire, lightning, hunger, disease or anything else, he is experiencing the reaction to his own past work.
According to Srila Visvanatha Cakravarti Thakura, King Pariksit obviously was not suffering the reaction of past karma. As a great devotee he was personally brought back home, back to Godhead, by the Lord.