Trematodes I Flashcards by Anika Eidson

What are the life stages of trematodes?

Adult
Egg
Miracidium
Sporocyst/Redia
Cercaria
Metacercaria (becomes adult)

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Describe adult trematodes

Found in the DH
Size varies
Pair of suckers (oral and ventral)
Monoecious (there are exceptions)
Egg laying stage
Hermaphroditic

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Where does the miracidium emerge from the egg?

Operculum

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What stage of trematodes emerges from mollusks?

Cercaria

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What is the encysted stage of the trematode life cycle?

Metacercaria

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What are metacercaria encysted in?

Environment or in an intermediate host

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What is Fasciola hepatica?

Liver fluke
Liver rot
Fascioliasis

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What is the DH of Fasciola hepatica?

Ruminants
Pigs
Horses
Wide range of mammalian wildlife

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What is the IH of Fasciola hepatica?

Lymnaeid snails

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What do Fasciola hepatica metacercariae encyst on?

Vegetation

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What is the site of Faciola hepatica in DH?

Bile ducts, liver

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What is the life cycle of Faciola hepatica?

Definitive host ingests metacercariae
Excyst in SI; juvenile fluke penetrates gut; abdominal cavoty to liver
Liver migration
To bile duct and matures to adult
Unembryonated eggs in bile to intestine; shed in feces to water in environment
Miracidia hatch in water
Penetrates lymnaeid snail, undergoes asexual reproduction
Cercariae emerge, attach to vegetation and encyst as metacercariae

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What is the pathology associated with Fasciola hepatica immature flukes?

Hepatitis
Fibrotic tracts
Hemorrhage
Anemia

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What is the pathology associated with Fasciola hepatica adults?

Anemia
Proliferation of bile duct epithelium
Cholangitis
Necrosis of duct walls
Fibrosis

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How does acute disease with Faciola hepatica occur?

Ingest large numbers of metacercariae

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What is the subacute form of Fasciola hepatica?

Massive infections; accumulated infections over time

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What is the chronic form of Fasciola hepatica?

Moderate infection

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How do you diagnose Fasciola hepatica eggs?

Fecal sedimentation

Oval, operculated, yellow

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Where are Fasciola hepatica juveniles found?

Liver parenchyma

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Can Fasciola hepatica infect humans?

Yes, but it is rare

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What is the DH of Fascioloides magna?

Primarily cervids (especially white tailed deer)

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What is the site of Fascioloides magna in the DH?

Bile ducts, liver

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What is the IH of Fascioloides magna?

Lymnaeid snails

What is the site of Fascioloides magna metacercariae?

Vegetation

What are the aberrant hosts of Fascioloides magna?

Sheep, goats

What are the accidental/incidental/dead-end hosts for Fascioloides magna?

``` Cattle Pigs Llamas Horses Moose ```

What is the life cycle of Fascioloides magna?

DH ingests metacercariae Excyst in SI; juvenile fluke migrates in abdominal cavity To liver: extended migration Matures to adults encysts in bile ducts (pairs) Unembryonated eggs in bile to intestine, shed in feces to water in environment Miracidia hatch in water Penetrates lymnaeid snail; undergoes asexual reproduction Cercariae emerge, attach to vegetation; form metacercariae

What is the pathology of Fascioloides magna in cervids?

Flukes in thin-walled cysts | Eggs leave cysts by channels to bile duct

What is the pathology of Fascioloides magna in accidental hosts?

Unapparent Closed cysts No trematode ova in feces Liver condemned

What is the pathology of Fascioloides magna in aberrant hosts?

Uninterrupted migration No cysts, adults or eggs Highly pathogenic, traumatic hepatitis

What are the methods of diagnosing Fascioloides magna?

Eggs detected by sedimentation | Adults encysted in liver

How is Fascioloides magna diagnosed in cattle?

Usually encapsulated | Dead or empty calcified capsules

How is Fascioloides magna diagnosed in sheep and goats?

Adults not present | Severe liver damage

What is the DH of rumen flukes- Paramphistomidae?

Cattle, goats, sheep

What is the site of rumen flukes- paramphistomidae?

Rumen and reticulum

What is the IH of Paraphistomum?

Aquatic snail

Is Paraphistomum pathogenic?

Not usually, but it is more pathogenic in young

Where is the metacercariae of Paraphistomum?

Vegetation

What is the life cycle of Paraphistomum?

DH ingests metacercariae Excysts in upper SI Juveniles migrate to abomasum to reticulum to rumen Matures to adults in rumen Unembryonated eggs passed in feces Miracidia hatch; penetrate aquatic snail; asexual reproduction occurs Cercariae released Cercariae encyts; form metacercariae on vegetation

How are Paraphistomum adults diagnosed?

In rumen/reticulum | Usually incidental finding at necropsy

How are Paraphistomum eggs diagnosed?

Sedimentation

What is Dicrocoelium dendriticum?

Lancet fluke | Little liver fluke

What is the DH of Dicrocoelium dendriticum?

Sheep, cattle, goats

What are the primary sites of Dicrocoelium dendriticum in the DH?

Liver Gall bladder Bile ducts

What is the 1st IH of Dicrocoelium dendriticum?

Land snail

What is the 2nd IH of Dicrocoelium dendiriticum?

Metacercariae in ants

What is the life cycle of Dirocoelium dendiriticum?

DH ingests ant with metacercariae Excyst in SI; juvenile fluke migrate through common bile duct to bile ducts and liver Adults in bile ducts, liver, gallbladder Embryonated eggs in feces Eggs ingested by land snail Miracidia hatches from egg in snail; asexual reproduction occurs Cercariae released in slime ball Ants ingest slime ball with cercariae Metacercariae form in abdomen/brain affect behavior

How do you diagnose Dicrocoelium dendriticum eggs?

Fecal sedimentation

Can Dicrocoelium dendriticum infect humans?

Yes, but it is rare | Accidental ingestion of ant

What is the DH of Platynosomum spp?

Domestic/wild cats

What is the 1st IH of Platynosomum spp?

Land snail

What is the 2 IH of Platynosomum spp?

Isopods (pill bugs), woodlice, cockroaches

What are the 3rd IH/paratenic host of Platynosomum spp?

Lizards, toads, geckos (swallow pill bug)

What is the life cycle of Platynosomum spp?

Cats ingests infected lizard/amphibian with metacercariae Excyst and move up SI to common bile duct to bile ducts to gallbladder Adults in cat bile and pancreatic ducts, gallbaldder Embryonated eggs in feces Land snail ingests eggs with miracidia; asexual reproduction, cercaria develop Cercariae are shed in sporocysts Sporocysts with cercariae ingested by isopods; metacercariae form Lizard/amphibian ingests isopod with metacercariae

What is the pathology associated with Platynosomum spp?

Cumulative infections "Lizard poisoning" Proliferative cholangitis Cirrhosis

How are Platynosomum spp eggs diagnosed?

Fecal sedimentation

How are Platynosomum spp adults diagnosed?

Ultrasound Liver biopsy Necropsy