[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 11 The Trematodes
11-11. Analyze case studies that include pertinent
patient information and laboratory data
and:
A. Identify each responsible trematode
organism by scientific name, common
name, and morphologic form, with
justification.
B. Identify the associated diseases and
conditions associated with the
responsible parasite.
C. Construct a life cycle associated
with each trematode parasite
present that includes corresponding
epidemiology, route of
transmission, infective stage,
and diagnostic stage.
D. Propose each of the following related
to stopping and preventing trematode
infections:
1. Treatment options
2. 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
performed, and predict the results of
those identified tests.
11-12. Given prepared laboratory specimens, and
with the assistance of this manual, the
learner will be able to:
A. Differentiate trematode organisms
from artifacts.
B. Differentiate the trematode organisms
from each other and from other
appropriate categories of parasites.
C. Correctly identify each trematode
parasite by scientific, common name,
and morphologic form based on its key
characteristic structure(s).
CASE STUDY 11-1
UNDER THE MICROSCOPE
Mr. Park, a 62-year-old Korean man, was seen for fatigue,
fever, and abdominal pain. On questioning the patient, it
was learned that Mr. Park is a commercial fisherman. His
liver function test results were abnormal, showing elevated
aspartate aminotransferase (350 IU/liter), alanine aminotransferase
(352 IU/liter), alkaline phosphatase (204 IU/
liter), and conjugated bilirubin (3.9 mg per deciliter) levels;
total bilirubin was 6.4 mg/dL. His white blood cell (WBC)
count was 13,000/mm 3 and eosinophilia value was 26%.
A computed tomography (CT) scan of the abdomen showed
dilation of the common bile duct. A tube was inserted into
the common bile duct and numerous leaf-shaped worms
FOCUSING IN
This chapter covers the class of helminth parasites
belonging to the class known as Trematoda
or Digenea. Commonly known as the flukes,
these parasites vary in egg, larva, and adult morphology
and reproduction processes. The trematodes
(another name for the parasites that belong
to Trematoda) can be divided into two groups,
the hermaphroditic (self-fertilizing) flukes that
infect organs and are foodborne, and the blood
flukes or schistosomes that are dioecious (parasites
that reproduce via separate sexes) and infect
were aspirated. The patient was given praziquantel and
had a quick and uneventful recovery.
Questions and Issues for Consideration
1. What parasite(s) do you suspect? Why? (Objective
11-11A)
2. Briefly describe the life cycle of the parasite(s). (Objective
11-11C)
3. What is the name of the disease/condition associated
with this parasite? (Objective 11-11B)
4. Propose a plan that Mr. Park could follow to prevent
future encounters with this parasite. (Objective 11-11D)
by direct penetration. Common to all trematodes
is their complex life cycles, which almost always
include mollusks (snails) as an intermediate host.
MORPHOLOGY AND LIFE
CYCLE NOTES
The trematodes pass through three morphologic
forms during their life cycle—eggs, multiple
larval stages, and adult worms. The eggs, which
are the primary morphologic form recovered in
human specimens, vary in appearance. Some
contain a lidlike structure that under the