Hymenolepsis infection is an infestation by one of two species of tapeworm: Hymenolepis nana or Hymenolepis diminuta. The disease is also called hymenolepiasis.
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:
- Gastrointestinal discomfort
- Itchy anus
- Poor appetite
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 easily from person to person.
Expect full recovery following treatment.
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.
Hymenolepiasis; Dwarf tapeworm infection; Rat tapeworm; Tapeworm - infection
Alroy KA, Gilman RH. Tapeworm infections. In: Ryan ET, Hill DR, Solomon T, Aronson NE, Endy TP, eds. Hunter's Tropical Medicine and Emerging Infectious Disease. 10th ed. Philadelphia, PA: Elsevier; 2020:chap 130.
White AC, Brunetti E. Cestodes. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 333.
Review Date 9/1/2021
Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.