You can get fish tape worms from eating raw fish, so the squeamishness isn't entirely unfounded. Fish tape worms are typically several yards long. That's yards, not feet. Nasty buggers.

That's some info pal. I am glad that I am a vegetarian

Most people, when they hear the word "sushi" are actually thinking of "sushimi", which is raw fish. And no it isn't cooked. It may however be marinated in citrus juice, which "cooks" the meat with acid instead of heat. But nonetheless, you can still get worms from it, because worm eggs and cysts require extreme temperatures to be killed. The OP may have been thinking of seared sushi, which not all sushi is. But even then, searing it only cooks the outside, and leaves the inside raw. Worm cysts can be distributed all throughout the flesh of the fish, so only cooking it partially doesn't protect you.

You can also freeze the fish solid for at least 24 hours, and that will kill any eggs or cysts that may be in the meat. Then you can eat it raw if you like.

I love those seaweed rolls and I love raw fish. I wonder is it healthy? It really tastes great especially with different sauces.

The chances of getting worms or some type of bacteria from eating sushi are actually pretty slim if you go to a reputable place. I have been informed from a couple of the restaurants I go to that their supplier flash freezes then quickly thaws the raw fish to kill any bacteria and/or worms that may be in it. My favorite type to get is Hokkigai Nigiri.

I thought fish had to be frozen solid for at least 24 hours in order to kill any eggs that may be in it.