Kaliya was a poisonous Naga king who lived in the Holy Yamuna River in Vrindavana during the previous Dwapara Yuga. Since it lived in that holy river, the water contains full of poison, and due to that, no one was able to take bath and drink water in that River. Kaliya was mentioned in the Bhagavata Purana.
Before living in the Yamuna River, Kaliya lived in an island, but since he was disturbed by Lord Garuda in that place, he has shifted his residence from that island to the Yamuna River. The residents of Vrindavana were unable to take bath and quench their thirst in the holy River Yamuna, due to the giant serpent Kaliya, and hence they informed it to Krishna. After knowing about these details, Lord Krishna was very angry with Kaliya, and he immediately went to the river Yamuna, and there he fought with him and removed his ego, and had given him a promise, that since the foot prints of Lord Krishna is affixed as a mark in the heads of Kaliya, Lord Garuda would be his friend and would never attack him.
On hearing these kind words from the mouth of Bhagavan Krishna, Kaliya had obeyed his orders and went to the Patala Loka with his family and lived peacefully in that world. After some time, Garuda appeared before him with a pleasing smile, and had become his dear friend.
From this incident, we can understand, if we get the grace of the almighty, no one would disturb us. Lord Krishna is away from worldly illusions, and he is the one who removes our diseases and brings goodness in our life. Those who read this story with full of devotion in their mind, would be blessed by Lord Krishna, and they would not suffer from poisonous diseases and from any other mental and body related ailments etc.
Let us worship Lord Krishna and the great snake king Kaliya and be blessed.