Not all foodborne illnesses make you wish you were dead because of the symptoms they cause; some feel queasy at the idea of a 30-foot (about 9 meters) long tapeworm living and breeding in their small intestine [source: WebMD].
Diphyllobothrium infection is caused by a parasitic flatworm called Diphyllobothrium latum. It's the largest tapeworm known to infect humans; the infection is acquired after consuming certain undercooked or raw fish, generally freshwater fish such as salmon and trout. Pickled and salted fish may also contain Diphyllobothrium larvae [source: Linklater].
Adults can grow larger than 44 feet (more than 10 meters) long in the small intestine, which is, itself, just 20 feet (6 meters) long and about an inch (2.5 centimeters) in diameter. Despite the size of the tapeworm, most diphyllobothrium infections don't cause any noticeable signs or symptoms, or none more severe than stomach pain and indigestion. But depending where the tapeworm is located and where its segments grow, diphyllobothrium infections may cause intestinal obstruction or gall bladder disease.