Thanks to a few Xrays they could see that his entire body had been infected with tapeworms. The doctors determined that it is due to him having eating a large amount of raw fish and cases as this are on the increase due to the popularity of Sushi.
Sashimi is the most expensive part on the Sushi menu and you would not expect, nor do they have a very effective way of preventing contamination due to it being… RAW and uncooked.
So if you are a Sushi lover there is not much you can do to prevent this apart from buying Sushi from more reliable and trusted sources.