I notice with a system infection like the ones that crawl into the head... the nest largely in the stomach and when bigger or disturbed by like spicy food or anti parasitic things they move around. I can literally feel mine like could be 30 at a time move quickly from my stomach to up my back and into my brain!!! they make like a slithering crackling sound when they push up into the opening from the back spine into head area.
you would think humans can't live this way but they can and they are quite resilient too ! im 30 healthy and work hard and successful and I know what I have and deal with it in some way daily.