Trematodes 3

Question 1

What are paramphistomes?

Answer 1

Rumen flukes

Question 2

Describe the life cycle of rumen flukes.

Answer 2

Eggs in feces are taken in by Galba truncatula intermediate host. Immature flukes undergo several stages in snail. Metacercariae form cysts on grass. Ingested by ruminants and digested in duodenum, releasing larval fluke. Plug feeding on duodenum leads to severe fluid and blood loss.

Question 3

What are the characteristics of paramphistomum eggs?

Answer 3

Susceptible to dehydration. Viable under moist environment, especially at low temperature 10˚C up to 6 months.

Question 4

What are the characteristics of paramphistomum metacercariae?

Answer 4

Viable under moist environment from 3-5 months. Perish in dry conditions.

Question 5

What is the PPP of paramphistomum?

Answer 5

3.5 months

Question 6

Describe the history of Paramphistome speciation.

Answer 6

Paramphostomum cervi was presumed to be the most common species in Europe. Now almost all isolates are Calicophoron daubneyi.

Question 7

What is the implication of identifying Calicophoron daubneyi rumen fluke in GB livestock?

Answer 7

It is a possible implication for liver fluke diagnosis.

Question 8

Describe the morphology of rumen flukes.

Answer 8

Pear-like conical body, anterior sucker in pharynx, ventral sucker at posterior end, eggs similar to F. hepatica.

Question 9

What are the characteristics of Paramphistome eggs?

Answer 9

Oval with operculum, colourless and slightly bigger than F. hepatica eggs.

Question 10

What signs can juvenile paramphistome stages in the duodenum cause?

Answer 10

Severe diarrhea, dehydration, and death.

Question 11

Which animals are the most susceptible to rumen flukes?

Answer 11

Youngstock: calves and lambs.

Question 12

In what areas do we see the most rumen fluke issues?

Answer 12

Tropics and to some extent in parts of Southern Europe.

Question 13

Describe the pathogenesis of the rumen fluke.

Answer 13

Most animals do not experience clinical signs. Occasionally, heavy infections can produce disease. Some fatalities have been reported where large numbers of rumen fluke were seen.

Question 14

What drug is effective at killing rumen flukes?

Answer 14

Oxyclozanide.

Question 15

What are some possible reasons for increased prevalence of rumen flukes?

Answer 15

Mild wet winters, wet summers, flooding, changes in farming practices, enzootic instability, change in species prevalence.

Question 16

What are the treatment and control methods for rumen flukes?

Answer 16

Routine treatment not required; monitor only. Oxyclozanide is effective. Closantel: oral only.

Question 17

What are the management practices to prevent rumen flukes?

Answer 17

Fence-off dangerous areas, no sheep on flukey pastures, monitor bulk milk tank, listen to annual forecast, treat sheep at risk periodically, treat cattle at risk at housing, problem with control in dairy cattle.

Question 18

Good pasture management for rumen flukes is similar to that for what?

Answer 18

F. hepatica.

Question 19

What is a common, insidious but important parasite of cattle and sheep?

Answer 19

Liver fluke.

Question 20

Presence of flukes compromises resistance to what?

Answer 20

Bacterial diseases.

Question 21

What should be an integral part of herd health planning?

Answer 21

Control of flukes.

Question 22

Rumen flukes have increased prevalence in which country recently?

Answer 22

Ireland.

Question 23

What is Dicrocoelium dendriticum?

Answer 23

Lancet liver fluke; have ants as another intermediate host which consume slime balls of snail containing metacercariae.

Question 24

What are the characteristics of schistosomes?

Answer 24

Blood flukes, separate sexes, round and fleshy, snail intermediate hosts, human and veterinary pathogens, eggs have distinctive spines.

Question 25

Describe the schistosome life cycle.

Answer 25

Eggs shed from humans in urine and feces and hatch to release miracidia which penetrate snail tissue. Sporocysts develop in snail and free swimming cercariae are released into water. Cercariae penetrate skin and lose tails, becoming schistosomulae. Travel through circulation in portal blood to liver and mature into adults. Paired adults migrate to mesenteric venules of rectum/bowel and bladder.

Question 26

What are the notable Schistosome species?

Answer 26

S. bovis, S. matthei, S. haematobium (people– hybrid with S. bovis) eggs in urine, S. mansoni, S. spindale, S. nasalis, S. japonica.

Question 27

Describe the pathogenesis of schistosomes.

Answer 27

Adults in the blood vessels lay eggs which travel to and are trapped in the liver. Hypersensitivity to antigens of larva inside egg cause formation of granulomas. Liver sinusoids become blocked and impede blood flow resulting in fibrosis.

Question 28

What pathologies are caused by fibrosis of the liver due to schistosomes?

Answer 28

Raised portal pressure, perihepatic shunting of blood, hepatomegaly, splenomegaly, formation of varices.

Question 29

What is Fascioloides magna?

Answer 29

Deer liver fluke.

Question 30

Describe the life cycle of F. magna.

Answer 30

Typical fluke life cycle with deer as definitive host, snail intermediate host, cattle, sheep, and moose as dead-end hosts.

Question 31

What are the characteristics of Fasciolopsis buski?

Answer 31

Infect man and pigs, zoonosis in Asia, intestinal tract obstruction/symptoms.

Question 32

Describe the life cycle of paragonimus organisms.

Answer 32

Unembryonated eggs into water orally or rectally from humans. Hatch miracidia which penetrate snails. Sporocyst -> rediae -> cercariae which hatch out of snail. Cercariae invade crustaceans and encyst into metacercariae. Ingested by humans via undercooked crustaceans. Metacercariae encyst in duodenum. Adults in lungs lay eggs which are excreted through sputum or swallowed and excreted through feces.

Question 33

Describe the life cycle of Opisthorchis (sinensis, viverini, and felineus) and Clonorchis sinensis.

Answer 33

Embryonated eggs passed in feces of human and ingested by snail. Miracidia -> sporocyst -> rediae -> cercariae in snail. Free-swimming cercariae encyst in the skin or flesh of fresh water fish. Ingested by humans as they consume fish and excyst in duodenum. Adults in biliary duct.

Question 34

How are Opisthorchis and Clonorchis associated with carcinogenesis?

Answer 34

Cholangiocarcinoma.

Question 35

How are schistosomes associated with carcinogenesis?

Answer 35

Squamous cell carcinoma.

Question 36

What are the characteristics of Typhlocolium cymbium/Trachiophilus cymbius?

Answer 36

Trematode of birds, particularly swans, ducks, and geese. Live in the trachea, cause inflammation and potentially dyspnea and death.

Question 37

What are the distinguishing features of the spines on eggs of S. mansoni, S. hematobium, and S. japonicum?

Answer 37

S. mansoni: lateral spine S. hematobium: terminal spine S. japonicum: small lateral spine

Question 38

What are the characteristics of Heterobilharzia americana?

Answer 38

Affects dogs along Gulf Coast of the USA. Intermediate hosts are freshwater lymnaeid snails (Galba humilis).

Question 39

Describe the pathogenesis of Heterobilharzia americana.

Answer 39

Cercariae penetrate skin, migrate to lungs/liver, then to mesenteric veins, where eggs penetrate into intestine and are released in feces. ## Footnote Causes liver damage, diarrhea, lethargy, and eosinophilia.

Question 40

How is Heterobilharzia americana diagnosed?

Answer 40

Sedimentation or fecal PCR.

Question 41

What are the control methods for schistosome infections?

Answer 41

Prevent swimming in areas where parasite occurs. Care with drinking water. Mass administration of at-risk humans with prazi. Snail control. Prevent pasture runoff. Fence off dangerous water supplies and supply clean drinking water for livestock. One Health Approach: 'test and treat'.

Question 42

What are the characteristics of Nanophyetus salmincola?

Answer 42

Transmits Neorickettsia helmintheoica. Seen along the Pacific rim in wild and domestic canids. Adults in SI.

Question 43

What are the clinical signs associated with Nanophyetus salmincola?

Answer 43

Pronounced lymphadenopathy, diarrhea, and possible death.

Question 44

What are the characteristics of Alaria alata?

Answer 44

Widespread in wild canids, especially foxes. Food animals (wild boars, etc.) are potential paratenic hosts with juvenile parasites in muscles. Adults in SI.

Question 45

Zoonotic infection by Alaria alata is recorded via what?

Answer 45

Eating 'Cuisses de grenouilles', wild boar.