While it may be ugly to look at there is no risk to people. It is a warm water copepod (more of a bug, not like a worm) and I have found them on fish in most the lakes in the Mt Hood National Forest (varying degree of infestation). My cleaning process works like this; gut, rinse, one pass on scaling, rinse, pass on scaling, rinse, and soak in brine for 15 minutes. I have vacuum sealed and frozen all my fish this year, whatever ones do not come off in the cleaning process fall right off after you thaw and rinse. The hard truth is we are going to see more and more of this kind of thing as waters warm up, and people move from one lake to another without cleaning gear. Its just like hunting take care of your meat and pay attention to what you find. It is best to check with ODFW or a local land manager (fish biologists) they know what is going on and what the risks are.
I would rather eat that fish then a cheese burger from the golden arches any day.
Here is the ODFW pdf on the critters...
http://www.dfw.state.or.us/fish/diseases/docs/copepod.pdf