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Parasitology > Trematodes - Trematoda > Flashcards

Trematodes - Trematoda Flashcards

1
Q

General trematode life stage

A

Adult –> egg –> miracidium –> sporocyst/redia –> cercaria –> metacercaria –> adult

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2
Q

Adult life stage

A
  • found in DH
  • variable size
  • pair of suckers (oral and ventral)
  • monoecious (except schistosomes)
  • egg laying stage
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3
Q

Egg life stage

A

Operculated!

- unembryonated vs embryonated

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4
Q

Miracidium life stage

A

Ciliated with penetration glands

- could be very host specific

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5
Q

Cercaria life stage

A

Mollusk intermediate host

- bores thru snail tissue

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6
Q

Metacercaria life stage

A

Encysted in environment or in an IH

  • encyst on vegetation: Fasciola hepatica, Fascioloides magna, Paramphistomum
  • encyst on IH: Dicrocoelium dendriticum (ants), Platynosomum fastosum (lizards), Paragonimus kellicotti (crawfish), Nanophyetus salmincola (salmon), Alaria (mesocercariae, frogs)
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7
Q

Fasciola hepatica

A

Liver fluke, liver rot, fascioliasis

  • DH: ruminants, pigs, horses, wide range of mammalian wildlife
  • IH: lymnaeid snails
  • metacercariae encyst on vegetation
  • site in DH: bile ducts, liver
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8
Q

Fasciola hepatica prevalence

A

Worldwide

- gulf coast, SE states, pacific northwest, rocky mountains, eastern Canada

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9
Q

Fasciola hepatica life cycle

A

DH ingests metacercariae –> excyst in SI, juvenile fluke penetrates gut, abdominal cavity to liver by 4-6 days –> liver migration for 6-8 wks –> to bile duct and matures to adult –> unembryonated eggs in bile to intestine, shed in feces to water in environment –> in 10-12 days miracidia hatch in water –> penetrates lymnaied snail, undergoes asexual repro –> cercariae emerge attach to vegetation and encyst as metacercariae

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10
Q

Fasciola hepatica pathology

A 
Immature flukes
- hepatitis
- fibrotic tracts
- hemorrhage
- anemia
Adults
- anemia
- proliferation of bile duct epithelium
- cholangitis
- necrosis of duct walls
- fibrosis (bile duct lamina propria, calcification)
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11
Q

Fasciola hepatica - acute disease

A

Primarily in sheep and goats that ingest large numbers of metacercariae

  • inappetence, decrease weight
  • abdominal pain
  • anemia
  • jaundice
  • ascites
  • depression
  • sudden death
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12
Q

Fasciola hepatica - subacute disease

A

Massive infection from accumulated exposure/ingestion over time

  • decrease weight
  • hemorrhagic anemia
  • liver failure
  • death
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13
Q

Fasciola hepatica - chronic disease

A

Moderate infection, subtle loss

  • decreased feed intake
  • decreased weight
  • decreased milk production
  • anemia
  • emaciation
  • submandibular edema
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14
Q

Fasciola hepatica diagnosis in ruminant host

A 
Eggs
- fecal sedimentation
- oval, operculated, yellow
Adults
- bile ducts
- conical anterior end (cephalic cone) and shoulders
Juveniles
- liver parenchyma
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15
Q

Fasciola hepatica treatment

A
  • triclabendazole (cattle and sheep only)
  • albendazole (sheep, cattle, goats) –> valbazen (adult flukes)
  • clorsulon (cattle) –> curatrem (immature adult flukes) –> ivomec plus (adult flukes)
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16
Q

Fasciola hepatica control

A

Avoid introduction of infected animals and hay (metacercariae)
- snail control: molluscicides (none approved in US), avoid snail habitats

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17
Q

Fasciola hepatica human infections

A

Rare in US

  • symptoms: acute, epigastric pain, prolonged fever, enlarged liver, anemia, jaundice, liver fibrosis
  • diagnosis: patent (4 months, ova in feces), ab testing, psuedofascioliasis (common in ppl who eat livers)
18
Q

Fascioloides magna

A
  • DH: primarily cervids (white tailed deer!)
  • IH: lymnaeid snails
  • metacercariae site: vegetation
  • aberrant hosts: sheep, goats
  • accidental/dead end hosts: cattle, pigs, llamas, horses, moose
19
Q

Fascioloides magna prevalence

A

New world parasite common to north america

20
Q

Fascioloides magna life cycle

A

DH ingests metacercariae –> excyst in SI, juvenile fluke migrate in abdominal cavity –> to liver, extended migration –> matures to adults in cysts 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 repro –> cercariae emergy, attach to vegetation, form metacercariae

21
Q

Fascioloides magna pathology - cervids

A

Natural definitive hosts (reservoirs)

  • no pathology unless heavy infection
  • flukes in thin walled cysts
  • eggs leave cysts by channels to bile duct
22
Q

Fascioloides magna pathology - accidental hosts

A

Large bovids (cattle), suids, llamas, horses, moose

  • unapparent
  • closed cysts
  • no trematode ova in feces –> no channels to escape!!
  • liver condemned (diffuse black pigment)
23
Q

Fascioloides magna pathology - aberrant hosts

A

Sheep and goats

  • uninterrupted migration
  • no cysts, adults, or eggs
  • highly pathogenic, traumatic hepatitis (hemorrhaging, necrosis, adhesive peritonitis)
24
Q

Fascioloides magna diagnosis

A 
Cervids
- fecal sedimentation
- adults encysted in liver
Cattle
- encapsulated, dead or empty calcified capsules
Sheep and goats
- adults not present
- severe liver damage
25
Q

Fascioloides magna treatment

A
  • oxyclozanide (WTD)
  • albendazole (sheep)
  • clorsulon (sheep and cattle)
26
Q

Fascioloides magna control

A

Avoid grazing on deer inhabited land

  • exclude deer
  • snail control (wetlands)
27
Q

Paramphistomidae

A

Rumen flukes

  • DH: cattle, goats, sheep
  • problem in the tropics
  • adults in rumen and reticulum
  • IH: aquatic snail, metacercariae on vegetation
  • usually non pathogenic, more pathogenic in young (diarrhea, enteritis)
  • have a sucker on both ends
28
Q

Paramphistomum life cycle

A

DH ingests metacercariae –> excysts in upper SI –> juveniles migrate to abomasum, reticulum, rumen –> matures to adults in rumen –> unembryonated eggs passed in feces –> miracidia hatch, penetrate aquatic snail, asexual repro –> cercariae released –> cercariae encysts, form metacercariae on vegetation

29
Q

Paramphistomum diagnosis

A 
Adults
- in rumen/reticulum
- stubby, pear shaped
- incidental finding at necropsy
Eggs
- fecal sedimentation
- oval, operculated, gray
30
Q

Paramphistomum treatment

A

Usually not treated

  • clorsulon
  • levamisole
31
Q

Dicrocoelium dendriticum life cycle

A

DH ingests ant with metacercariae –> excyst in SI, juvenile fluke migrate thru common bile duct and liver –> adults in bile duct. liver, gallbladder –> embryonated eggs in feces –> eggs ingested by land snail –> miracidia hatches from egg in snail, asexual repro –> cercariae released in slime ball –> ants ingest slime ball with cercariae –> metacercariae form in abdomen/brain, affect behavior, ants climb grass

32
Q

Dicrocoelium dendriticum pathology

A

Mild to inapparent

  • advanced infections: hepatic cirrhosis, proliferation of bile duct epithelium, condemned liver
  • sheep: anemia, edema, decreased wool production and lactation
33
Q

Dicrocoelium dendriticum diagnosis

A 
Eggs
- fecal sedimentation
- brown, oval, operculated, embryonated
Adults
- flat, lancet shaped
34
Q

Dicrocoelium dendriticum treatment/control

A
  • treatment: usually not treated, abldendazole or fenbendazole
  • control: avoid grazing early morning/late evening, eliminate IH
35
Q

Dicrocoelium dendriticum human infections

A
  • rare in humans: middle east, kenya, czech republic
  • accidental ingestion of ant
  • symptoms of liver bile duct involvement (mild)
  • diagnosis: eggs in feces
  • treatment: praziquantel
36
Q

Platynosomum

A
  • worldwide, southeastern US, Hawaii, central/south america
  • DH: domestic and wild cats –> bile and pancreatic ducts, liver, gallbladder
  • 1st IH: land snail
  • 2nd IH: isopods (pill bugs), woodlice, cockroaches
  • 3rd IH: lizards, toads, geckos
37
Q

Platynosomum life cycle

A

Cat ingests infected lizard/amphibian with metacercariae –> excyst and move up SI to common bile duct to bile ducts and gallbladder –> adults in cat bile and pancreatic ducts, gallbladder –> embryonated eggs in feces –> land snail ingests eggs (w/ miracidia), asexual repro (cercariae develop) –> cercariae shed in sporocysts –> sporocysts with cercariae ingested by isopods, metacercariae form –> lizard/amphibian ingests isopod with metacercariae

38
Q

Platynosomum pathology

A

Asymptomatic

  • cumulative infection: “lizard poisoning”, proliferative cholangitis, cirrhosis
  • anorexia, diarrhea, vomiting, weight loss
  • liver: enlargement, fibrosis, jaundice
39
Q

Platynosomum diagnosis

A 
Eggs
- fecal sedimentation
- oval, brown, operculated
- contain miracidia
Adults
- ultrasound
- liver biopsy
- necropsy
40
Q

Platynosomum treatment/control

A
  • praziquantel

- prevent predation of IH

Parasitology (28 decks)

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