You know the old saying: " If you love something, set it free. If it comes back to you, it's yours. If it doesn't, it never was." Yes it applies to grown children returning home on holidays, but it also applies to the roundworm known as Strongyloides stercoralis.
Normally, your pet S. stercoralis carries out a very straight-forward relationship. In its dirt-loving infective form, it enters your skin and tracks a long, winding road through your lymphatic and repertory systems, till it finally reaches your small intestines. Here, the adult females make their home and, for up to five years, they pump out larvae. The young then leave home via your excrement to explore the world.
But empty bowel syndrome isn't a forgone conclusion with your roundworms, because sometimes the growing larvae don't actually leave. If you "happen" to have a case of constipation, they might wind up deciding to get to know their host a little better instead. This means a trip through the intestines wall and a weaving journey to such destinations as the lungs and liver.
Other selections: The small intestine isn't the only place to host your parasitic guests. Consider raising some Acanthamoeba keratitis in your eyeballs or strap on a few ticks for a chance at lucking out with some Babesiosis.