We have outdoors cats that eat a whole lot of mice, voles and shrews (and other animals) and with some regularity end up with white worm-like parasites of about 1cm length leaving their intestines and sticking to their fur until they get lost. Obviously, by that time a deworming is called for.
Now I wanted to identify the parasites in question in order to know what particular danger they pose to humans when left by cats somewhere. It's basically always this kind even for cats that have never met, the cats are common house cats, the location is Western Germany. What I found in Wikipedia does not differentiate according to commonality and I've not found a good image match either, possibly missing the right maturity stage.