[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 10 The Cestodes
10-8. Select the specimen(s) of choice and
diagnostic approach for the recovery of
each of the cestodes.
10-9. Compare and contrast the cestodes in
terms of the key features that the parasites
have in common, as well as the features
that distinguish them.
10-10. Given a description, photomicrograph,
and/or diagram of a cestode, correctly:
A. Identify and/or label the designated
characteristic structure(s)
B. State the purpose of the designated
characteristic structure(s)
C. Identify the organism by scientific
name, common name, and
morphologic form.
10-11. Analyze case studies that include
pertinent patient information and
laboratory data and:
A. Identify each responsible cestode
organism by scientific name, common
name, and morphologic form.
B. Identify the associated diseases and
conditions associated with the
responsible parasite.
C. Construct a life cycle associated with
each cestode parasite present that
includes corresponding epidemiology,
route of transmission, infective stage,
and diagnostic stage.
D. Propose each of the following related
to eliminating and preventing cestode
infections:
1. Treatment options
2. A prevention and control plan
E. Recognize sources of error, including
but not limited to those involved in
specimen collection, processing, and
testing and propose solutions to
remedy them.
F. Interpret laboratory data, determine
specific follow-up tests to be done, and
predict the results of those identified
tests.
10-12. Given prepared laboratory specimens, and
with the assistance of this manual, the
learner will be able to:
A. Differentiate cestode organisms and/or
structures from artifacts.
B. Determine the cestode organisms from
each other and from other appropriate
categories of parasites.
C. Correctly identify each cestode parasite
by scientific name, common name, and
morphologic form based on its key
characteristic structure(s).
CASE STUDY 10-1
UNDER THE MICROSCOPE
A 14-year-old, severely mentally disabled boy, who was
institutionalized in a state facility, was evaluated for episodes
of chronic diarrhea, anal pruritis, restless nights, and
occasional vomiting. Significant laboratory findings were a
10% eosinophilia, an IgE level of 225 IU/mL, and microscopic
examination of a stool concentrate that revealed
two thin-shelled, oval-shaped eggs measuring 45 by 35 um
in size and containing three pairs of hooklets and polar
filaments.
Questions and Issues for Consideration
1. What is the most likely identification of the parasite in
question? (Objective 10-11A)
2. Why is this organism unique among the intestinal cestodes?
(Objective 10-9)
3. What is the preferred treatment for infection caused by
this organism? (Objective 10-11D)
FOCUSING IN
This chapter consists of a discussion of the class
of multicellular worms noted for their flat or
ribbon-like appearance known as Cestoda (the
cestodes). The characteristic appearance of the
cestodes forms the basis for the common names
associated with this group, flatworms or
tapeworms.
MORPHOLOGY AND LIFE
CYCLE NOTES
There are three morphologic forms that exist in
the typical cestode life cycle—egg, one or more
larval stages, and adult worm. With one exception,
the egg consists of a hexacanth embryo
(also known as an oncosphere) defined as the
motile, first larval stage characterized by the