I'm not one that likes fish much---definetly haven't eaten sushi--but I had plenty of liver (and other types) of flukes.
Barefoot's or Humaworm (along with liver flushing) would tell you if you have them. I started seeing them immediately in the toilet the next morning after starting on the herbal dewormers.
Where did I get them? I lived in an area where the livestock is known to always have liver flukes-- I don't eat meat that has any redness to it, but perhaps it was through the beef, or being around the actual cattle (we worked for a ranch)...but I worked in my yard alot-- which had slugs, and I always had a garden...perhaps it came from the vegetables too.
There was also a creek that ran behind our house we swam in...and I used to swim in a natural warm spring pond alot as a child.