Hymenolepis infection
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Related Key Words and Synonyms: Dwarf tapeworm, Hymenolepiasis.
Diagnosis
The diagnosis depends on the demonstration of eggs in stool specimens. Concentration techniques and repeated examinations will increase the likelihood of detecting light infections.
Differential Diagnosis
History and Symptoms
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 tapeworm infection does not generally cause weight loss. You cannot feel the tapeworm inside your body.
Laboratory Findings
Microscopy:
A: Egg of Hymenolepis diminuta. These eggs are round or slightly oval, size 70 to 86 µm by 60 to 80 µm, with a striated outer membrane and a thin inner membrane. The space between the membranes is smooth or faintly granular. The oncosphere has six hooks (of which at least four are visible at this level of focus). Image contributed by Georgia Department of Public Health.
B: Egg of Hymenolepis nana. These eggs are oval and smaller than those of H. diminuta, their size being 30 to 55 µm. On the inner membrane are two poles, from which 4 to 8 polar filaments spread out between the two membranes. The oncosphere has six hooks (seen as dark lines at 8 o'clock). Image contributed by Georgia Department of Public Health.
C: Artifact resembling a H. nana egg. However, no hooks and no polar filaments are visible in the artifact.
Macroscopic:
F: Three adult Hymenolepis nana tapeworms. Each tapeworm (length: 15 to 40 mm) has a small, rounded scolex at the anterior end, and proglottids can be distinguished at the posterior, wider end. Image contributed by the Georgia Division of Public Health.
Risk Stratification and Prognosis
- 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 tapeworm.
- Eggs are infectious (meaning they can re-infect you or infect others) immediately after being shed in feces.
Treatment
Acute Pharmacotherapies
A prescription drug called praziquantel is given. The medication causes the tapeworm to dissolve within the intestines. Praziquantel is generally well tolerated. Sometimes more than one treatment is necessary.
Primary Prevention
- Wash hands with soap and water after using the toilet, and before handling food.
- If you work in a childcare center where you change diapers, be sure to wash your hands thoroughly with plenty of soap and warm water after every diaper change, even if you wear gloves.
- 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.
References
- http://www.cdc.gov/ncidod/dpd/parasites/hymenolepis/default.htm
- http://www.dpd.cdc.gov/dpdx/HTML/Hymenolepiasis.htm
Acknowledgements
The content on this page was first contributed by: C. Michael Gibson, M.S., M.D.