Don't know about any parasite that gets under the skin and have never seen a leech anywhere in my work or vacation travels throughout North America. We do have a water-borne parasite in lakes and streams in the mountains of the western US and Canada called "giardia" that can make people very ill if they drink unfiltered water. It is carried in the intestinal tracts of a number of animals who use those streams. But it's easy to avoid--don't drink, wash dishes, or brush your teeth in unfiltered mountain stream water.