That's ridiculous. You can't cast out sickness like it was a demon. Christians still get sick. Paul and Timothy both had health problems. Epaphroditis almost died.
(1 Timothy 5:23 NIV) Stop drinking only water, and use a little wine because of your stomach and your frequent illnesses.
(Galatians 4:15 NIV) What has happened to all your joy? I can testify that, if you could have done so, you would have torn out your eyes and given them to me.
(Philippians 2:25-27 NIV) But I think it is necessary to send back to you Epaphroditus, my brother, fellow worker and fellow soldier, who is also your messenger, whom you sent to take care of my needs. {26} For he longs for all of you and is distressed because you heard he was ill. {27} Indeed he was ill, and almost died. But God had mercy on him, and not on him only but also on me, to spare me sorrow upon sorrow.
If the cause of your sickness is not a natural phenomenon you better cast out the devil and his deeds.
You have right to your opinion but I want you not to be myopic about the content of my post. The point above all is to tell about the efficacy of the blood of Jesus, and that can never be overemphasis. The blood of Jesus can do anything, infact it can do all things.