Echinochasmus metacercariae are seen commonly in gills of many freshwater fish in Oregon - dace, chub, pikeminnow, whitefish etc. The immature trematode has a distinct ring of spikes around its oral sucker. Fish are one of the intermediate hosts; the final host is probably a bird.
Hosts
Many freshwater fish in Oregon
Detection Methods:
microscopic exam - wet mount
Target tissue
gills