Common name: Lung fluke
The adult worms measure 8 to 16 mm long.
Cross section of a pair of adult flukes
The egg matures (2 to 3 weeks) and hatches in water. The miracidium finds and penetrates a snail. Sporocysts, and then redia develop in the snail. Cercariae develop in the redia, and when mature emerge from the snail. The cercariae swim around until they find a crustacean which they penetrate and encyst in the heart, liver, or muscles as metacercaria. When the definitive host eats the crayfish the metacercaria excyst in the host's small intestine. The young fluke penetrates the gut wall and wanders in the peritoneal cavity for 1 to 14 days before penetrating the diaphragm and then the lungs. The adult flukes are normally found in pairs within cysts in the lung. The cyst has an opening to a bronchiole. Eggs are laid in the cyst and pass out to the bronchiole. They are passed up with the lung mucus and are swallowed. The eggs then pass out with the feces. The prepatent period is about 3 to 36 days.
Egg 90 X 50 µm
Common Diagnostic Test
© University of Pennsylvania 2004
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