[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 11 The Trematodes
Operculum
Thickened rim
around operculum
(called shoulders)
Developed
miracidium
Small knob
B
A
Average size: 30 m by 15 m
FIGURE 11-5 A, Clonorchis sinensis egg. B, Clonorchis sinensis egg. (B from Mahon CR, Lehman DC, Manuselis G:
Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
encysted metacercariae. Maturation of the immature
flukes takes place in the liver. The adult
worms take up residence in the bile duct.
Epidemiology
C. sinensis is endemic in areas of the Far East,
including China, especially the northeast portions,
Taiwan, Korea, Vietnam, and Japan. Reservoir
hosts include fish-eating mammals, dogs,
and cats. More than 35 million people are
infected, and the numbers have tripled to 15
million in China alone in the last decade. Much of
this increase may be the result of aquaculture.
Clinical Symptoms
Average size: 2 cm by 0.5 cm
FIGURE 11-6 Clonorchis sinensis adult.
Asymptomatic. Light infections typically
occur without any obvious symptoms.
Clonorchiasis. Persons infected with a heavy
worm burden often experience symptoms that
include fever, abdominal pain, eosinophilia, diarrhea,
anorexia, epigastric discomfort, and occasional
jaundice. Enlargement and tenderness of
the liver and leukocytosis may also occur. Liver