A man who contends he got a three-metre tapeworm after eating undercooked fish has sued a Chicago restaurant.
In the lawsuit filed yesterday, Anthony Franz said he ordered salmon salad for lunch from Shaw's Crab House in 2006 and fell violently ill.
He later passed the giant parasite, which a pathologist determined came from undercooked fish, such as salmon.
Franz's lawsuit seeks $US100,000 ($A115,000) from Shaw's and its parent company, Lettuce Entertain You Enterprises, contending the restaurant's staff was negligent in serving him improperly cooked fish.
But Carrol Symank, vice-president of food safety for Lettuce Entertain You, said the tapeworm didn't come from Shaw's.
"We have done a thorough investigation and we're confident the restaurant is not the source," he said.
According to the website mayoclinic.com, tapeworms can measure up to 15 metres long.