forcepsOnce the biopsy is obtained, it should be placed immediately into container with adequate volume of fixative.

In ulcerated tumour, Biopsies should be taken from the periphery that includes normal and diseased tissue.

1. 1
Knowledge University
College of Science
Department of Medical Laboratory Science
Level 3
(Hymenolepiasis)
Theoretical Helminthology
Lecture 5
2025-2026
Dr. Abdulrahman Ibrahim

2. Hymenolepiasis -cestodes
2
Hymenolepiasis is caused by two cestodes (tapeworm)
species:-
(1)Hymenolepis nana(the dwarf tapeworm, adults
measuring 15 to 40 mm in length).
Hymenolepis nanais the most common cause of all
cestode infections, and is encountered worldwide. In
temperate areas its incidence is higher in children and
institutionalized groups.

3. Hymenolepiasis - cestodes
(2)Hymenolepis diminuta(rat tapeworm, adults
measuring 20 to 60 cm in length).Hymenolepis
diminutais a cestode of rodents infrequently seen in
humans and frequently found in rodents.
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4. H.nana (1.5-4 cm length)
4

5. H.nana- How the parasite transmitted?
One becomes infected by:
(1) Accidentally ingesting dwarf tapeworm eggs. This
can happen by
a- Ingesting focally contaminated foods or water.
b- By touching mouth with contaminated fingers.
c- By ingesting contaminated soil.
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6. H.nana- How the parasite transmitted?
(2) People can also become infected if they accidentally
ingest an infected arthropod (intermediate host, such as
a small beetle or mealworm) that has gotten into food.
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7. Hymenolepis nana life cycle
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8. Hymenolepis nana life cycle (cont.)
The right side of life cycle related to autoinfection:
Q/ What is hexacanth embryo?
Q/ a- What are the (three) infective stage of H.nana?
b- What is the way of infection of each type?
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9. 1.Vomiting
2.Anorexia
3.Abdominal pain
4.Diarrhea
5.Irritability
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H.Nana Symptoms

10. (1) Good hygiene, public health and sanitation programs.
(2) Elimination of infected rats help topreventthe spread
of hymenolepiasis.
(3) Preventingfecal contamination of food and water in
institutions and crowded areas is of primary importance.
(4) Washing hands thoroughly (water and soap).

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Prevention

11. After studying the previous figures, you can answer the
following questions:
Q1/ Explain the differences between autoinfection cycle
and common life cycle.
Q2/ Give the definitive and intermediate hosts of
H.nana .
Q3/ Name the infective stage of infection and
autoinfection of H.nana.
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