Two of my favorite subjects, fishing and parasitology! Here's the scientifical version:
Fish tapeworm infestations are pretty much found wherever raw, pickled or undercooked freshwater fish is eaten by folks who caught the fish in lakes/streams where other infected folks/animals took a crap or there is some other source of raw sewage release.
It's found everywhere in N. America from Alaska to Florida, and includes the anadromous family of fish we all love so much, salmon and steelhead.
Released worm ova hatch into free-swimming larvae when they reach freshwater and continue to develop if consumed by small freshwater crustaceans within a couple days.
Then along comes a fish who dines on the larva-carrying crustacean, and the tapeworm larva then penetrates the musculature of the fish, forming elongated and INFECTIOUS larva.
It's when people eat mishandled, infected fish meat that they risk getting tapeworm (Diphyllobothrium latum). To protect yourself, you really need to thoroughly cook all salmon and freshwater fish; even when it is appropriately cooked, you can get tapeworms if you sample infected fish flesh during the preparation process. And for the sushi/sashimi lovers, better to freeze the fish at -10 degrees Celsius for at least 48 hours before chowing down.
Most infected people are asymptomatic, except for occasional stomach pain and cramping, puking, fatigue and weight loss--geez, who doesn't feel like that on occasion?!
I'm surprised at the roommate with the 7ft long butt noodle, usually it's only the eggs that come out in stool. Maybe he consumed something the worm did not like!