Tapeworm infection - Hymenolepsis

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Hymenolepsis infection is an infestation by 1 of 2 species of tapeworm: Hymenolepis nana or Hymenolepis diminuta. The disease is also called hymenolepiasis.

Alternative Names

Hymenolepiasis; Dwarf tapeworm infection; Rat tapeworm; Tapeworm - infection


Hymenolepis live in warm climates and are common in the southern United States. Insects eat the eggs of these worms.

Humans and other animals become infected when they eat material contaminated by insects (including fleas associated with rats). In an infected person, it is possible for the worm's entire life cycle to be completed in the bowel, so infection can last for years.

Hymenolepis nana infections are much more common than Hymenolepis diminuta infections in humans. These infections used to be common in the southeastern United States, in crowded environments, and in people who were confined to institutions. However, the disease occurs throughout the world.


Symptoms occur only with heavy infections. Symptoms include:

  • Diarrhea
  • Gastrointestinal discomfort
  • Itchy anus
  • Poor appetite
  • Weakness

Exams and Tests

A stool exam for the tapeworm eggs confirms the diagnosis.


The treatment for this condition is a single dose of praziquantel, repeated in 10 days.

Household members may also need to be screened and treated because the infection can be spread from person to person.

Outlook (Prognosis)

Expect full recovery following treatment.

Possible Complications

Health problems that may result from this infection include:

  • Abdominal discomfort
  • Dehydration from prolonged diarrhea

When to Contact a Medical Professional

Call your health care provider if you have chronic diarrhea or abdominal cramping.


Good hygiene, public health and sanitation programs, and elimination of rats help prevent the spread of hymenolepiasis.


Fischer PR, White AC. Adult tapeworm infections. In: Kliegman RM, Stanton BF, St Geme JW III, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 302.

Mega JD, Galdos-Cardenas G, Gilman RH. Tapeworm infections. In: Magill AJ, Hill DR, Solomon T, Ryan ET, eds. Hunter's Tropical Medicine and Infectious Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 126.

Version Info

  • Last reviewed on 9/10/2015
  • Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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