Hymenolepis nana: Life Cycle, Pathogenesis and Lab Diagnosis

By Sushmita Baniya •  Updated: 05/17/22 •  6 min read

Habitat

Note: It is unique that it is the only cestode that completes its life cycle in one host–humans.

Morphology

Scolex (head): 

Proglottides (segments):

Eggs: (please refer to the lab diagnosis section below).

Life Cycle of Hymenolepis nana

The life cycle of Hymenolepsis nana can be completed via a direct cycle or indirect cycle. In the direct cycle, an intermediate host is not required and the entire development from the larval to the adult stage takes place in humans. Arthropod (rat fleas and beetles), acts as an intermediate host in the indirect cycle.

Lifecycle of Hymenolepis nana
  1. When the eggs of Hymenolepis nana is passed in the stool, they are immediately infective. In the external environment, eggs cannot survive more than 10 days.
  2. Eggs develop into cysticercoids when they are ingested by the arthropod intermediate hosts such as beetles and fleas.
  3. Humans are infected when they ingest cysticercoid-infected arthropods.
  4. Humans can also get infected when they ingest food or water contaminated with embryonated eggs.
  5. Then after the ingestion, the oncospheres present in the eggs are released.
  6. Then in the small intestine, they can gradually develop into adults.
  7. Adults live in the small intestine in the ileal region and produce the gravid proglottids.
  8. Eggs get released from the genital atrium of the gravid proglottids or when the disintegration of the proglottids occurs in the small intestine.
  9. If eggs remain in the intestine, autoinfection may result. Intestinal villus is penetrated by the oncospheres (hexacanth larvae) and later develops into the cysticercoid larvae.

Pathogenesis

Mode of infection

Hymenolepiasis

Other rare symptoms are anorexia, nausea, and vomiting.

 Laboratory diagnosis

 Sample: Stool specimen

Collection of stool 

Collect all fecal specimens before the administration of antibiotics or antidiarrheal agents. 

Reject any specimen that appears to be dry on the surface or edges.

Transport

Direct Microscopy

Eggs:

b.      Eosinophilia

c.       ELISA Test

Treatment

Prevention and Control

Reference

Sushmita Baniya

Hello, I am Sushmita Baniya from Nepal. I am a postgraduate student of M.Sc Medical Microbiology. I am interested in Genetics and Molecular Biology.

We love to get your feedback. Share your queries or comments

This site uses Akismet to reduce spam. Learn how your comment data is processed.