The line between demons and parasites is unclear, but we know that demons use parasites to hurt people. Such as in the book of Job, where satan is allowed to test Job with disease and he becomes infected with worms. We also know that parasites, like demons, influences peoples behaviours, thoughts, cravings and so on. Parasites , like demons, never enable people unless it benefits themselves in some way. The parasite does everything to benefit itself at the hosts expense. With that being said it becomes clear that Spiritual Warfare is necessary as a part of life. I ask that everyone contribute what they know about spiritual warfare.
Fortunately for us there is a history of Spiritual Combat through out the ages on how to take out these demons. I will start by mentioning the "Jesus Prayer" which is known to burn the demons. It is very simple,
Lord Jesus Christ, Son of God, Have Mercy on me, a sinner
This prayer is to be repeated like a mantra all day long burning the demons / parasites. A great book to read on this is "the way of the pilgrim". There is also the Philokalia which explains this in detail. May God defeat the demon / parasites through his mercy, Amen.