| Paragonimus westermani | The bronchial or lung fluke; a species that causes paragonimiasis, found chiefly in Japan, Korea, Taiwan, China, the Philippines, and Thailand; eggs are coughed up in sputum or swallowed and passed in the faeces; miracidia invade Melania snails, and produce large numbers of stumpy-tailed cercariae that leave the snail and crawl into muscles and viscera of crayfish or crabs and encyst; in humans the excysted worms invade the wall of the gut and migrate through the diaphragm into the lungs; the developing parasites cause an intense inflammatory reaction and eventually induce fibrous-walled nodules that usually contain a pair of adult worms, along with exudate, eggs, and remains of red blood cells; the fibroparasitic nodules may become contiguous and form multiloculated cystlike structures; in some instances, the flukes involve the brain, liver, peritoneum, intestine, or skin. Synonym: Paragonimus ringeri. (05 Mar 2000) |
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