Diphyllobothriasis is defined as infection with the cestode Diphyllobothrium latum or other Diphyllobothrium species. It is endemic in areas where humans frequently consume raw or pickled fish. Diphyllobothriasis is a worldwide disease that affects people near fresh water and appropriate intermediate hosts. D latum commonly infects persons residing in Europe, Africa, and the Far East. Areas where consumption of raw or precooked fish is popular tend to have endemicity.
Diphyllobothriasis has no reported age predilection or sexual predilection. In addition, it has no known racial predilection, except as would be expected on the basis of geographic and cultural factors.
Most persons with diphyllobothriasis are asymptomatic. Sometimes when symptomatic the most common symptoms are abdominal pain, indigestion or dyspepsia, passage of proglottids. Other less common symptoms that are associated with this disease include fatigue, diarrhea, dizziness, numbness of extremities, and sensation of hunger. The actual results of infestation are not well studied; megaloblastic anemia is known to be a possible consequence.
Diphyllobothriasis is treated by pharmacologic means; surgical treatment is not required unless otherwise indicated. Even in the face of decreased vitamin B-12 levels, less than 2% of patients with diphyllobothriasis develop anemia. Vitamin supplementation may be required in severe cases. Praziquantel is considered the drug of choice for D latum infection, with niclosamide as an alternative. Resistant or advanced cases of diphyllobothriasis may require consultation with a gastroenterologist and an infectious disease specialist. The neurologic and hematologic manifestations of vitamin B-12 deficiency respond well to supplementation. The patient’s stool should be reexamined on day 7 after therapy to test for cure. The presence of any Diphyllobothrium segments or ova in the stool on posttherapy day 7 constitutes a treatment failure. If the first course of treatment fails, a second identical course of therapy may be administered.