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For further information, see CMDT Part 35-18: Noninvasive Cestode Infections

Key Features

Essentials of Diagnosis

  • Light infection generally asymptomatic

  • Abdominal discomfort, anorexia, diarrhea seen in heavy infection, which is common, especially in children

General Considerations

  • Six tapeworms infect humans frequently

  • The small tapeworms are

    • Hymenolepis nana (dwarf tapeworm, 25–40 mm; can reach 5 cm)

    • Hymenolepis diminuta (rodent tapeworm, 20–60 cm)

    • Dipylidium caninum (dog tapeworm, 10–70 cm)

  • The large tapeworms are

    • Taenia saginata (beef tapeworm, up to 25 m)

    • Taenia solium (pork tapeworm, 7 m)

    • Diphyllobothrium latum (fish tapeworm, 10 m)

  • H nana is the only tapeworm that can be transmitted between humans

  • Infection follows ingestion of food contaminated with human feces

  • Eggs hatch in the intestines, where oncospheres

    • Penetrate the mucosa

    • Encyst as cysticercoid larvae

    • Then rupture after about 4 days to release adult worms

  • Autoinfection can lead to amplification of infection

  • Infection with H nana, the related rodent tapeworm H diminuta, or the dog tapeworm D caninum can also follow accidental ingestion of infected insects

Demographics

  • Infections are common in warm areas, especially with poor hygiene and institutionalized populations

Clinical Findings

Symptoms and Signs

  • Light infections are generally asymptomatic

  • Heavy infections may cause

    • Diarrhea

    • Abdominal discomfort

    • Anorexia

Differential Diagnosis

  • 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

Laboratory Tests

  • 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

Medications

  • Praziquantel

    • Treatment of choice

    • Dosage is 25 mg/kg orally

    • Not effective against maturing cysts

    • For heavy infections, repeat treatment after 1 week and screen after therapy to document cure

    • Side effects include headache, malaise, dizziness, abdominal pain, nausea

  • Niclosamide

    • Alternative therapy

    • For adults, 2 g chewed is effective

    • Continue therapy daily for 1 week

    • Side effects include nausea, malaise, abdominal pain

Outcome

When to Refer

  • For persistent or progressive infection despite treatment

Reference

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Craig  P  et al. Intestinal cestodes. Curr Opin Infect Dis. 2007 Oct;20(5):524–32.
[PubMed: 17762788]  

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