The lyme bug can curl up into a cyst form, with a waxy type of coating, which lives in nerve cells. It doesn't do much damage there, but it sits there and waits for the right situation to come out and multiple and do its thing. Substances like steroids send it into hiding in cyst form. Flagyl is one of the few medications good against this form, but there are others. They all have some difficulties in dealing with, and that's why some doctors feel that the disease is never totally licked, because you never get all the cysts. I believe my doctors think I will always have some cysts, and what we know that's helpful, is that the bugs die off with amoxicillin when they come out, so that if they come out again, we can give them a good hit!