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Hymenolepis infection or infection with the dwarf tapeworm is found worldwide. It is most often seen in children in countries in which sanitation and hygiene are inadequate. Although the dwarf tapeworm infection rarely causes symptoms, it can be misdiagnosed for pinworm infection.


What is Hymenolepis nana infection?

The dwarf tapeworm or Hymenolepis nana is found worldwide. Infection is most common in children, in persons living in institutional settings, and in people who live in areas where sanitation and personal hygiene is inadequate.

How did I get infected?

One becomes infected by accidentally ingesting dwarf tapeworm eggs. This can happen by ingesting fecally contaminated foods or water, by touching your mouth with contaminated fingers, or by ingesting contaminated soil. People can also become infected if they accidentally ingest an infected arthropod (intermediate host, such as a small beetle or mealworm) that has gotten into food.

Adult dwarf tapeworms are very small in comparison with other tapeworms and may reach 15-40 mm (up to 2 inches) in length. The adult dwarf tapeworm is made up of many small segments, called proglottids As the dwarf tapeworm matures inside the intestine, these segments break off and pass into the stool. An adult dwarf tapeworm can live for 4-6 weeks. However, once you are infected, the dwarf tapeworm may reproduce inside the body (autoinfection) and continue the infection.

What are the symptoms of a dwarf tapeworm infection?

Most people who are infected do not have any symptoms. Those who have symptoms may experience nausea, weakness, loss of appetite, diarrhea, and abdominal pain. Young children, especially those with a heavy infection, may develop a headache, itchy bottom, or have difficulty sleeping. Sometimes infection is misdiagnosed as a pinworm infection.

Contrary to popular belief, a dwarf tapeworm infection does not generally cause weight loss. You cannot feel the dwarf tapeworm inside your body.

How is dwarf tapeworm infection diagnosed?

Diagnosis is made by identifying dwarf tapeworm eggs in stool. Your health care provider will ask you to submit stool specimens collected over several days to see if you are infected.

Is a dwarf tapeworm infection serious?

No. Infection with the dwarf tapeworm is generally not serious. However, prolonged infection can lead to more severe symptoms; therefore, medical attention is needed to eliminate the dwarf tapeworm.

How is a dwarf tapeworm infection treated?

Treatment is available. A prescription drug called praziquantel is given. The medication causes the dwarf tapeworm to dissolve within the intestine. Praziquantel is generally well tolerated. Sometimes more than one treatment is necessary.

Can infection be spread to other family members?

Yes. Eggs are infectious (meaning they can re-infect you or infect others) immediately after being shed in feces.

What should I do if I think I have a dwarf tapeworm infection?

See your health care provider for diagnosis and treatment.

How can dwarf tapeworm infection be prevented?

To reduce the likelihood of infection you should:

  • Wash your hands with soap and warm water after using the toilet, changing diapers, and before preparing foods.
  • Teach children the importance of washing hands to prevent infection.
  • When traveling in countries where food is likely to be contaminated, wash, peel or cook all raw vegetables and fruits with safe water before eating.


    Causal Agent

    Hymenolepiasis is primarily caused by the cestode (tapeworm) species, Hymenolepis nana (the dwarf tapeworm, adults measuring 15 to 40 mm in length).

    Life Cycle:

    Life cycle of Babesia microti

    Eggs of Hymenolepis nana are immediately infective when passed with the stool and cannot survive more than 10 days in the external environment. When eggs are ingested by an arthropod intermediate host (various species of beetles and fleas may serve as intermediate hosts), they develop into cysticercoids, which can infect humans or rodents upon ingestion and develop into adults in the small intestine. A morphologically identical variant, H. nana var. fraterna, infects rodents and uses arthropods as intermediate hosts. When eggs are ingested (in contaminated food or water or from hands contaminated with feces), the oncospheres contained in the eggs are released. The oncospheres (hexacanth larvae) penetrate the intestinal villus and develop into cysticercoid larvae. Upon rupture of the villus, the cysticercoids return to the intestinal lumen, evaginate their scoleces, attach to the intestinal mucosa and develop into adults that reside in the ileal portion of the small intestine producing gravid proglottids . Eggs are passed in the stool when released from proglottids through its genital atrium or when proglottids disintegrate in the small intestine. An alternate mode of infection consists of internal autoinfection, where the eggs release their hexacanth embryo, which penetrates the villus continuing the infective cycle without passage through the external environment. The life span of adult worms is 4 to 6 weeks, but internal autoinfection allows the infection to persist for years.

    For more information view the source:Center for Disease Control

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