Diphyllobothriasis is defined as infection with the cestode Diphyllobothrium latum or other Diphyllobothrium species (eg, Diphyllobothrium nihonkaiense). It is endemic in areas where humans frequently consume raw or pickled fish.
A full-grown Diphyllobothrium worm can range from 1-15 m in length and is the longest human tapeworm. It consists of up to 3000-4000 proglottids. The scolex, as noted, has 2 sucking grooves, also called bothria. Proglottids are typically wider than they are long, which is why D latum is called the broad tapeworm. One study demonstrated that when a mixture of vitamin B-12 and gastric juice was placed in the ileum, a hematologic remission resulted; such a remission did not occur when the mixture was taken orally. These results suggest that D latumpreferentially absorbs vitamin B-12 in the blood, preventing vitamin B-12-IF complexes from reaching receptors in the small bowel.
In symptomatic persons, the following are the most common symptoms:
Indigestion or dyspepsia
Passage of proglottids
Microscopic stool examination for ova and parasites (the usual basis for the diagnosis) Complete blood count (CBC) Hemoglobin level and hematocrit Mean cell volume Peripheral smear Vitamin B-12 level Folate level
The standard treatment for diphyllobothriasis, as well as many other tapeworm infections is a single dose of Praziquantel, 5–10 mg/kg PO once for both adults and children. An alternative treatment is Niclosamide, 2 g PO once for adults or 50 mg/kg PO once. One should note that Praziquantel is not FDA approved for this indication and Niclosamide is not available for human use in the United States.