Sometimes referred to as the "Jewish Grandmother's tapeworm," Diphyllobothrium latum is a cestode transmitted to humans through the consumption of raw or undercooked fish. D. latum is the largest human tapeworm, reaching up to 30 feet long in some cases. Infected Scandinavian fishermen carried the parasite with them during their immigration to the United States. In the early twentieth century, Jewish grandmothers, during the preparation of gefilte fish, a traditional Jewish dish, sampled the fish in order to enure that it was cooked to their liking. During the sampling process these women inadvertently consumed raw fish and became infected with D. latum, inspiring the name "Jewish Grandmother's tapeworm."
A human becomes infected after consuming raw or undercooked fish. The scolex attaches to the intestine, and the adult parasite resides in the small intestine. During the diagnostic stage unembryonated eggs leave the body in feces. The eggs become embryonated in water, and coracidia hatch from the egg. The coracidia are injested by crustaceans, inside which they mature into procercoid larvae. Fresh water fish become infected with the parasite when they consume infected crustaceans. The procercoid larvae mature into plerocercoid larvae, and the fish enters the infective stage when the parasite migrates to the musculature. This fish is typically ingested by a larger fish prior to human consumption.
Diphyllobothrium latum generally causes very little harm to humans. While the majority of infections are asymptomatic, infections can cause diphyllobothriasis, which is characterized by abdominal discomfort, diarrhea, vomiting, and weightloss. Furthermore, severe infections can cause intestinal obstructions, and proglottid migration may cause cholecystitis or cholangitis. Anemia is a rare side effect of infection, and typically only occurs in heavy, chronic infections, resulting from parasitic absorbtion of vitamin B12 in the small intestine. Infection can last decades if undetected.
Paleoparasitological analyses of samples taken from Neolithic sites revealed the presence of Diphyllobothrium sp. eggs. These sites included four Neolithic lakeside settlements in Germany and Switzerland. Organic matter was removed and subjected to a series of techniques intended to isolate parasitic remains, and were eventually analyzed by light and electronic microscopy. The matter organic matter analyzed is believed to be of human origin, as it contains plants associated with human life at the time. Depending on the location of the site, 18 to 73% of the samples contain evidence supporting the presence of Diphyllobothrium sp. A quick increase in occurence was correlated to an increase in other parasties associated with freshwater fish consumption, which may indicate a cultural shift leading to dietary changes, like the increased consumption of freshwater fish. The Diphyllobothrium sp. increase was followed by an equally paced decrease in occurence, which may indicate lifestyle changes, such as dietary changes or improved cooking practices, or the arrival of a new population. This finding presents the earliest evidence for the existence of the Diphyllobothrium sp. parasite to date, placing the parasite in the time period between 3917-3905 B.C. The discovery of the parasite at high concentrations during this time period indicates that it was likely one of the most common parasitic infections of the time, and provides a connection between cultural changes and changes in infection rates.
Scholz, Tomas, Garcia, Hector, Kuchta, Roman, and Barbara Wicht. 2009. Update on the Human Broad Tapeworm (Genus Diphyllobothrium), Including Clinical Relevance. Clinical Microbiology Reviews 22(1): 146-160.
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Professor Schall's Biology 246 Lecture