Parasitic spirits exist in many places and come in many forms. When you look at physical parasites they have so many different sources; everything from fungi to tape worm the same can be said for energetic parasites. Most parasites are not that bad, hell a lot of people have minor parasites and never find out. Parasites can be dangerous especially for practitioners as they have more energy and higher quality energy. More powerful parasites will target those who are stronger and without internal or external defense. You are most likely to attract them in spiritual realms when projecting or in areas with lots of people especially those who are mentally, physical, or spiritually weakened. As for ways to get rid of them, there are many and it depends on what your practice is. A relatively easy one is to enchant your soap and ritualistically clean yourself in a shower. It is relatively simple and cheap. There are parasites this will not help with, but its a good start. Dm me if you need any help.