Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-18: Noninvasive Cestode Infections + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Infections are generally asymptomatic Nonspecific gastrointestinal symptoms, including diarrhea, may occur Prolonged heavy infection can lead to megaloblastic anemia and neuropathy from vitamin B12 deficiency +++ General Considerations ++ Six tapeworms infect humans frequently The large tapeworms are Taenia saginata (the beef tapeworm, up to 25 m in length) Taenia solium (the pork tapeworm, 7 m) Diphyllobothrium latum (the fish tapeworm, 10 m) The small tapeworms are Hymenolepis nana (the dwarf tapeworm, 25–40 mm) Hymenolepis diminuta (the rodent tapeworm, 20–60 cm) Dipylidium caninum (the dog tapeworm, 10–70 cm) Eggs passed in human feces that reach fresh water are taken up first by crustaceans, which in turn are eaten by fish, both of which are intermediate hosts Human infection results from eating undercooked freshwater fish Infection with multiple worms over many years can occur Nonhuman reservoir hosts include dogs, bears, and other fish-eating mammals +++ Demographics ++ D latum is found in temperate regions + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Large tapeworm infections are generally asymptomatic Nonspecific gastrointestinal symptoms (eg, diarrhea) Megaloblastic anemia and neuropathy can result from prolonged heavy infection +++ Differential Diagnosis ++ Beef, pork, dwarf, rodent, or dog tapeworm Chronic fatigue syndrome Chronic hepatitis Irritable bowel syndrome Amebiasis Ascariasis Enterobiasis (pinworm, mostly children) Hookworm disease Strongyloidiasis Celiac disease or tropical sprue Pernicious anemia (D latum) + Diagnosis Download Section PDF Listen +++ ++ Diagnosis is usually made based on the identification of characteristic eggs or proglottids in stool Egg release may be irregular, so examination of multiple specimens or concentration techniques may be needed + Treatment Download Section PDF Listen +++ +++ Medications ++ Praziquantel Treatment of choice Single dose of 5–10 mg/kg is highly effective Side effects include headache, malaise, dizziness, abdominal pain, nausea Niclosamide Alternative therapy Single dose (2 g for adults chewed) is effective Side effects include nausea, malaise, abdominal pain + Outcome Download Section PDF Listen +++ +++ Follow-Up ++ A disintegrating worm is usually passed within 24–48 h of treatment. Since efforts are not generally made to recover and identify the scolex, cure can be presumed only if regenerated segments have not reappeared 3–5 months later If it is preferred that parasitic cure be established immediately, the head (scolex) must be found in posttreatment stools; a laxative is given 2 h after treatment, and stools must be collected in a preservative for 24 h. To facilitate examination, toilet paper must be disposed of separately +++ When to Refer ++ If confirmation of the diagnosis is needed or if symptoms are progressive despite therapy If there is difficulty distinguishing tapeworm-induced B12 deficiency from pernicious anemia + Reference Download Section PDF Listen +++ + +Craig P et al. Intestinal cestodes. Curr Opin Infect Dis. 2007 Oct;20(5):524–32. [PubMed: 17762788]