Hymenolepis nana (Dwarf Tapeworm) Infection

ByChelsea Marie, PhD, University of Virginia;

William A. Petri, Jr, MD, PhD, University of Virginia School of Medicine

Reviewed ByChristina A. Muzny, MD, MSPH, Division of Infectious Diseases, University of Alabama at Birmingham

Reviewed/Revised Modified Oct 2025

v1015259

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Hymenolepis nana, a tiny intestinal tapeworm, is one of the most common human cestodes; the life cycle does not require an intermediate host. Infection is treated with praziquantel or niclosamide., a tiny intestinal tapeworm, is one of the most common human cestodes; the life cycle does not require an intermediate host. Infection is treated with praziquantel or niclosamide.

Symptoms and Signs
Diagnosis
Treatment

H. nana is only 15 to 40 mm long. It differs from other tapeworms in that it requires only 1 host, but can also cycle through 2. Its larvae migrate only within the gut wall, and its life span is relatively short (4 to 6 weeks).

H. nana is more frequent in populations, particularly children, living in conditions of poverty and poor hygiene, particularly when fleas are present.

H. nana has 3 modes of infection:

Indirect 2-host cycle: Rodents are the primary definitive hosts, and grain beetles, fleas, or other insects feed on contaminated rodent droppings as intermediate hosts; humans can become infected by ingesting parasitized insects.
Human-to-human oral-anal cycle: Eggs are passed from one human to another or eggs recycle externally in a single host (an external autoinfection process in which eggs are shed in feces and re-ingested by the same individual).
Internal autoinfection: Eggs hatch within the gut and initiate a second generation without ever exiting the host. Autoinfection can result in large numbers of worms and symptoms.

Symptoms and Signs of Hymenolepis nana Infection

Infections are often asymptomatic, but heavy infections may cause crampy abdominal pain, diarrhea, anorexia, pruritis ani, and nonspecific systemic symptoms. On occasion, H. nana is misdiagnosed as pinworm infection.

Diagnosis of Hymenolepis nana Infection

Microscopic examination of stool for ova and proglottids

Diagnosis is made by finding eggs in stool samples.

Treatment of Hymenolepis nana Infection

PraziquantelPraziquantel
Alternatively, nitazoxanide or, outside the United States, niclosamideAlternatively, nitazoxanide or, outside the United States, niclosamide

The treatment of choice for H. nana infection is (1).

Praziquantel orally once Praziquantel orally once

Alternatives include nitazoxanide and niclosamide (not available in the United States).Alternatives include nitazoxanide and niclosamide (not available in the United States).

A stool sample should be repeated 1 month after therapy is completed to verify cure.

Prevention includes limiting exposure to rodents, beetles, and fleas.

Treatment reference

1. Centers for Disease Control and Prevention. Clinical Care of Hymenolepiasis (Dwarf Tapeworm). November 8, 2024. Accessed September 19, 2025.

Drugs Mentioned In This Article

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