Trematodes Flashcards
What are the characterisitcs of organisms in the phylum Platyhelminthes?
dorsoventrally compressed body
tegument with or without spines
digestive system with mouth but no anus (blind sac)
usually hermaphroditic
What are the morphological characteristics of organisms in the subclass Digenea?
2 attachment organs (ex. oral sucker and acetabulum)
digestive system composed of ceca
have excretory and nervous systems
hermaphroditic
How do trematodes usually cause disease?
they eat blood, obstruct ducts and vessels, and destroy organs and tissues during feeding, migrations, or by pressure necrosis.
Egg accumulation also causes problems.
What are the hosts of Fasciola hepatica? Where are they found in the definitive hosts?
Definitive hosts- cattle, sheep, goats
found in bile ducts
Intermediate host- aquatic snails in the genus Lymnaea
What is the infective stage of F. hepatica? How is it transmitted?
The definitive host ingests the infective stage, metacercariae
What determines the severity of fascioliasis in animals?
The number of metacercariae ingested
What are the signs of chronic fascioliasis in sheep? In cattle?
Sheep: lack of vigor, appetite loss, pale mm, brittle wool, bottle jaw
Cattle: digestive distrubance, constipation, possible diarrhea. Calves are emaciated and weak.
How is fascioliasis diagnosed? What is the exception?
Fecal sedimentation- however, eggs are not shed in the feces for acute fascioliasis
necropsy
What are the hosts of Platynosomum concinnum (syn. fastosum)? Where are they found in the definitive host?
Definitive- cats
found in the liver, plus bile and pancreatic ducts
Intermediate- terrestrial snails, lizards, toads, geckos, skinks
Paratenic- pill bugs
What is the infective stage of Platynosomum concinnum (syn. fastosum)? How is it transmitted?
Transmission occurs when a cat eats the metacercariae in the 2nd or 3rd intermediate host, usually a lizard
What are the signs of Platynosomum concinnum (syn. fastosum)?
Usually it does not cause more than a temporary loss of appetite
“Lizard poisoning” could also develop- weight loss, emaciation, diarrhea, vomiting, jaundice, death
chronic form- enlarged bile ducts/liver, liver failure
What are the hosts of Heterobilharzia americana? Where are they found in the definitive host?
Definitive- dogs, bobcats, raccoons
found in the mesenteric and hepatic veins
Intermediate- aquatic snails
What is the infective stage of Heterobilharzia americana? How is it transmitted?
Transmission occurs when the infective stage, the cercariae, penetrate the skin or mm of definitive host
What are the signs of *H. americana * infection? Is it a zoonotic disease?
Diarrhea, vomiting, weight loss, lethargy, hypercalcemia
Cercariae can cause skin irritation and egg migration can cause inflammation
Yes- causes swimmer’s itch in humans
How is H. americana diagnosed?
fecal sedimentation
