Bailey & Scott's Diagnostic Microbiology: Liver and Lung Trematodes Flashcards

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liver flukes

adult trematodes living in biliary ducts, encapsulated in the lungs; freshwater snail is intermediate host; dogs, pigs, and rabbits are reservoir/definitive hosts; caused by feces contaminating water when eggs enter snail and develop, fish eat the snail, and metacercariae are ingested


liver fluke lab diagnosis

eggs recovered in stool with sedimentation concentration; acute and chronic serology tests; NAAT


Fasciola hepatica

worldwide distribution, more common in areas where cattle and sheep are raised and humans consume raw watercress (Europe, Middle East, and Asia); sheep liver fluke; snails and water plants are IH; human infections rare


Fasciola hepatica clinical presentation

light infections lead to fever, abdominal pain, diarrhea, jaundice, and liver tenderness; heavy infections larvae migrate to intestinal walls, lungs, heart, skin, or brain; months in acute phase-migration, chronic phase-adult fluke within bile ducts causing intermittent biliary obstruction and inflammation


Fasciola hepatica eggs

elliptoid, operculated, unembryonated measuring 130-150 um long by 70-90 um wide


Fasciola hepatica adults

measure 30mm long by 15 mm wide, large and broadly flattened; anterior end cone-shaped; reside in bile ducts of liver


Clonorchis sinensis

Chinese liver fluke common in Korea, China, Taiwan, and Vietnam caused by ingestion of contaminated raw, pickled, smoked, salted, or dried fish


Clonorchis sinensis clinical presentation

light infections usually asymptomatic, heavy infections lead to bile duct obstruction; acute-migration and chronic phase-cholangitis, cholelithiasis, acute pancreatitis


Clonorchis sinensis eggs

28-34 by 14-18 um ovoid, thick brownish-yellow shell operculum with distinct shoulders; hook-like protrusion at abopercular end; miracidium visible inside egg


Clonorchis sinensis adults

10-25 by 2-5 mm wide biliary passages of liver of definitive host


Opisthorchis viverrini

Common in Southeast Asia-Northeast Thailand, Cambodia, Laos, and Vitenam-estimated 10 million people infected


Opisthorchis viverrini clinical presentation

light infections usually asymptomatic, heavy infections lead to bile duct obstruction; acute phase-migration, chronic phase leads to cholangitis, cholelithiasis, acute pancreatitis, and associated with bile duct carcinoma


Opisthorchis viverrini eggs

19-30 by 10-20 um


Opisthorchis viverrini adults

7 mm long by 1.5 mm wide and reside in bile ducts of definitive host; differ from Clonorchis in shape of testes


Paragonimus spp.

lung flukes; three common species with different geography


Paragonimus westermani

lung flute transmitted by ingestion of improperly cooked or raw crabs or crayfish; worms live in lungs and produce eggs found in sputum or feces; species widely distributed but most common in Southeast Asia including Japan; Reservoir dog and cat, IH freshwater snail, secondary IH crab or crayfish


Paragonimus mexicanus

Paragonimus species common to Central and South America; pigs are reservoir hosts, freshwater snail IH, crab or crayfish secondary IH


Paragonimus kellicotti

Paragonimus species common to North and South America


Paragonimus westermani clinical presentation

acute phase invasion and migration-diarrhea, abdominal pain, fever, cough, urticaria, hepatosplenomegaly, pulmonary abnormalities, and EOS; chronic leads to pulmonary manifestations including cough, discolored sputum expectorated, hemoptysis, and chest radiographic abnormalities; PMN's and EOS, fibrotic capsules and cysts form, and pronounced pulmonary inflammation


Paragonimus westermani eggs

80-120 by 45-65 um yellow-brown, ovoid with thick shell; operculum clearly visible at one end with shoulders; unembryonated when passed


Paragonimus westermani adults

8-16 mm large, robust, ovoid flukes; hermaphroditic with lobed ovary located anterior to two branching testes with oral and ventral suckers


Paragonimus westermani lab diagnosis

eggs recovered from sputum or pleural effusions or stool using sedimentation-concentration; sero sometimes useful, NAAT, and lung lesions visual on x-ray