Tapeworm Infection, Dwarf

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

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)

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

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

When to Refer

• For persistent or progressive infection despite treatment