No. the larvae that would infect humans aren't competent swimmers. If you are a little zooplankton predator like a copepod, there would be little L2 stage roun

No. the larvae that would infect humans aren't competent swimmers. If you are a little zooplankton predator like a copepod, there would be little L2 stage roundworm larvae of various species whipping about (after having hatched from eggs that came out of a larger predator's gut) trying to attract attention and get eaten so they could continue the lifecycle (often, they'd need to get eaten by at least one larger predator to mature). There are Ascaris-like worms in water that can affect humans, see: Anisakis. But you wouldn't get infected by larvae in the environment, you'd have to eat undercooked fish that ate the zooplankton that ate the L2 worms and get infected through the gut once they are L3 stage. Ah - Dracunculus aka guinea worm is a another you could get from water, but you'd need to actually drink the copepods.