At least in the US parasite risk from sushi is very low because nearly all seafood sold/served is put through a deep freeze cycle.

But if you're slicing up something you just caught that could be an issue. It's a concern with hunting/game as well. Most people who get trichinosis in the US get it from eating bear apparently.

I crossed bear off my menu a long time ago! To my chagrin, the bears did not reciprocate.