Hymenolepis nana

• Hymenolepis nana

  
  

  (Dwarf Tapeworm)
• H. nana is different from the other tapeworms because it does not require an obligatory intermediate animal host
• Infection of H. nana

  1. Accidental ingestion of eggs from fecally-contaminated food or water

  2. Touching mouth with contaminated fingers

  3. Ingestion of contaminated soil

  4. Accidental ingestion of rice or flour beetles containing infective larvae
• Rodents serve as additional source of infection
• Life cycle of H. nana in human host

  1. Eggs (infective stage) gain entrance into human host

  2. Eggs transform into cysticercoid larvae

  3. Larvae mature into adult worms capable of self-reproduction

  4. Eggs released after disintegration of gravid segments

  5. Some eggs passed out through feces, some remain inside human host and hatch into larvae, starting new cycle (autoinfection)
• dwarf tapeworm - most common tapeworm recovered in the United States.
• Hymenolepiasis

  A disease
• Hymenolepiasis

  • Most patients are asymptomatic
  • In cases of high worm burden, patients complain of nausea, weakness, loss of appetite, diarrhea, and abdominal pain
  • In young children with heavy infection, anal itchiness (pruritus ani) may occur
  • Can lead to headaches due to difficulty sleeping
  • Can be confused with a pinworm infection
  • Autoinfection may lead to hyper-infection syndrome which can result in secondary bacterial infection and spread of the worms to other tissues of the body
• The dwarf tapeworm has been found in all parts of the world except Australia and New Zealand.
• Diagnosis

  Established by finding of the characteristic eggs in stool specimen
• Praziquantel


  The drug of choice for treatment
• Niclosamide

  Can be an alternative drug for treatment
• Important preventive measures

  • Proper hygiene and waste disposal
  • Control of transport host population
  • Rodent control
  • Proper storage of grains and flour to prevent infestation with flour and grain beetles
• Prompt treatment of infected individuals must be instituted to prevent the spread of the parasite