Trematoda 1-3 Flashcards
Parasites of veterinary importance
Helminths: parasitic worms, large and multicellular
The term “helminth” includes a number of phyla, many of which are unrelated (phylogenetically) but they have superficial similarities:
-they are vermiform or “worm-like” in form-
Phylum Nematoda (roundworms)
Phylum Platyhelminthes (flatworms)
Class Cestoda (tapeworms)
“Class Trematoda (flukes: e”n”doparasites)”
Class Monogenea (skin flukes: ec”t”oparasites)
Class Turbellaria (free-living flatworms, some parasitic forms)
Phylum Acanthocephala (thorny-headed worms)
Phylum Annelida (segmented worms) not parasitic (leeches)
Trematodes are often referred to as digeneans or digenean flukes
Digenea: a subclass of ? in the Platyhelminthes, consisting of parasitic flatworms (known as flukes), they typically have two suckers, one ventral and one oral. Adults are particularly common in the ? tract, but occur throughout the organ systems of all classes of vertebrates. Once thought to be closely related to the Monogenea, it is now recognised that they are closest to the ? and that the Monogenea are more closely allied with the ?. Around 6,000 species have been described to date.
Aspidogastrea: is a small group of ? comprising about 80 species. It is a subclass of the ?, and sister group to the Digenea. Species range in length from approximately one millimeter to several centimeters. They are parasites of ? and ? molluscs and vertebrates (cartilaginous and bony fishes and turtles). Maturation may occur in the mollusc or vertebrate host. None of the species has any economic importance, but the group is of very great interest to biologists because it has several characters which appear to be ?.
Trematodes are often referred to as digeneans or digenean flukes
Digenea: a subclass of trematodes in the Platyhelminthes, consisting of parasitic flatworms (known as flukes), they typically have two suckers, one ventral and one oral. Adults are particularly common in the digestive tract, but occur throughout the organ systems of all classes of vertebrates. Once thought to be closely related to the Monogenea, it is now recognised that they are closest to the Aspidogastrea and that the Monogenea are more closely allied with the Cestoda. Around 6,000 species have been described to date.
Aspidogastrea: is a small group of flukes comprising about 80 species. It is a subclass of the trematoda, and sister group to the Digenea. Species range in length from approximately one millimeter to several centimeters. They are parasites of freshwater and marine molluscs and vertebrates (cartilaginous and bony fishes and turtles). Maturation may occur in the mollusc or vertebrate host. None of the species
has any economic importance, but the group is of very great interest to biologists because it has several characters which
appear to be archaic.
NOTE: key characteristics of trematodes - cistodes; always comes for exam!!!!!
TREMATODES
Key characteristics
Life cycles
Fasciola hepatica
Fasciola hepatica, also known as the common ? fluke or ? liver fluke, is a ? trematode of the class Trematoda, Phylum Platyhelminthes. It infects the ? of various mammals, including humans
NOTE: key characteristics of trematodes - cistodes; always comes for exam!!!!!
TREMATODES
Key characteristics
Life cycles
Fasciola hepatica
Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic trematode of the class Trematoda, Phylum Platyhelminthes. It infects the livers of various mammals, including humans
Trematodes (flukes)
- Dorso-ventrally ?, ?-like
- Oral and ventral ? for attachment and feeding
- Hermaphroditic (sexually reproducing) but can ?-reproduce
- Large operculate eggs – sedimentation
- Do NOT have ? life cycles so means it needs a ? host
- Typically ? host spectrum (except gastropod 1st IH)
- As in other flatworms, there is no ?, and waste material must be egested through the mouth, or via specialized cells – known as ? cells
Trematodes (flukes)
- Dorso-ventrally flattened, leaf-like
- Oral and ventral suckers for attachment and feeding
- Hermaphroditic but can cross-reproduce
- Large operculate eggs – sedimentation
- Do NOT have direct life cycles (means they have an essential iH (usually snail) - trematode infection - snail zombie recall)
- Typically broad host spectrum (except gastropod 1st IH)
- As in other flatworms, there is no anus, and waste material must be egested through the mouth, or via specialized cells – known as flame cells
TREMATODES (flukes) - Fasciola sp.
- fasciolosis/iasis *
fasciola hepatica infects ? ducts in sheep liver (pipestem liver)
The larval stages, metacercaria (in grass foliage), burrow through the lining of the ? and into the ? cavity. They then migrate through the intestines and liver, and into the ? ducts. Inside the bile ducts, they develop into ? flukes
TREMATODES (flukes) - Fasciola sp.
- fasciolosis/iasis *
fasciola hepatica infects bile ducts in sheep liver (pipestem liver)
The larval stages, metacercaria, burrow through the lining of the intestine and into the peritoneal cavity. They then migrate through the intestines and liver, and into the bile ducts. Inside the bile ducts, they develop into adult flukes
Trematodes (flukes)
Amphimerus sp.
High prevalence of the ? fluke Amphimerus sp. in domestic ? and ? in an area for human amphimeriasis in Ecuador.
? fluke: Phyllodistomum conostomum in H&E section of ureter
Host: arctic char ? alpinus
A few from fish: adult trematodes (often called digeneans)
High prevalence of the liver fluke Amphimerus sp. in domestic cats and dogs in an area for human amphimeriasis in Ecuador.
Kidney fluke: Phyllodistomum conostomum in H&E section of ureter
Host: arctic char Salvelinus alpinus
Trematodes (flukes) – ‘Simple’ life cycle
Final Host (DH): Adult
Environment: egg – called ?
Intermediate host: rediae – cercaria
Environment: ?
Final host: immature adult to adult
Final host consumes ? in the environment
Fasciola hepatica, has a global distribution and has been known as an important parasite of ? and ?
Trematodes (flukes) – ‘Simple’ life cycle
Final Host (DH): Adult
Environment: egg – called miracidium
Intermediate host: rediae – cercaria
Environment: metacercaria
Final host: immature adult to adult
Final host consumes metacercaria in the environment
Fasciola hepatica, has a global distribution and has been known as an important parasite of sheep and cattle
Trematodes (flukes) - eggs
Operculate
sedimentation in diagnostics
Trematodes (flukes) - mircacidium (?)
- Penetrate into the ? intermediate host
Trematodes (flukes) - eggs
Operculate
sedimentation in diagnostics
Trematodes (flukes) - mircacidium (egg)
- Penetrate into the snail intermediate host
miracidium: a free-swimming ciliated larval stage in which a parasitic fluke passes from the egg to its first host, typically a snail.
Trematodes (flukes) – IH
Intermediate hosts of Fasciola hepatica are freshwater snails from the family Lymnaeidae. ** This stage can be quite ?-specific **
- developmental stage in the IH
Trematodes (flukes) – IH
Intermediate hosts of Fasciola hepatica are freshwater snails from the family Lymnaeidae. This stage can be quite host-specific!
- developmental stage in the IH
Trematodes (flukes) – cercaria
Free-swimming: encysts as a ? in the environment or in a 2nd IH
Cercarial Dermatitis
see pic!!
? itch, also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain parasites that infect some birds and mammals
? is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed * ? *
Trematodes (flukes) – cercaria
Free-swimming: encysts as a metacercaria in the environment or in a 2nd IH
online: metacercaria = the final larval form of a trematode, in which the larva is encysted, tailless and infective.
swimmers itch, also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain parasites that infect some birds and mammals
schistosoma is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed * schistosomiasis *
Trematodes (flukes) – metacercaria
2nd IH -fish
Trematodes (flukes) – ‘complex’ life cycle
Adult : final and definitive host
Egg : environment – miracidium
Rediae : ? host (snail)
Cercaria: (into ? again)
** Metacercaria : 2nd ?; ?; or ? **
Young adult to adult : final and ? host
Final host consumes metacercaria in the 2nd ? or ? or in the ?
Trematodes (flukes) – metacercaria
2nd IH -fish
Trematodes (flukes) – ‘complex’ life cycle
Adult: final and definitive host
Egg: environment – miracidium
Rediae: intermediate host (snail)
Cercaria: (into environment again)
** Metacercaria : 2nd IH; PH; or environment **
Young adult to adult : final and definitive host
Final host consumes metacercaria in the 2nd IH or PH or in the environment
e.g. life cycle of Bucephalus polymorphous
Trematodes (flukes) – ‘complex’ life cycle
e.g. life cycle of Bucephalus polymorphous
Or possibly a bird: many digeneans are found in water associated birds, and ballyhoo are often found swimming very near the water surface (FYI)
Trematodes (flukes) – life cycle
Cercaria penetrate the 2nd ? host (tadpoles) becoming infective ?
Tadpoles or frogs (following the metamorphosis), may be ingested by a number of ? hosts (e.g., other frogs, snakes) or directly by the ? host, e.g. the dog.
Common in North American mammals with a wide range of definitive hosts known, including cattle, lynx, martens, skunks, bobcats, foxes, coyotes, and wolves
- ? americana : trematode in the family Diplostomatidae.
- All species infect carnivorous mammals, living in their small ? as mature worms
- Development via the ?
- Uses intermediate and ? hosts
Or possibly a bird: many digeneans are found in water associated birds, and ballyhoo are often found swimming very near the water surface (FYI)
Trematodes (flukes) – life cycle
Cercaria penetrate the 2nd intermediate host (tadpoles) becoming infective mesocercariae
Tadpoles or frogs (following the metamorphosis), may be ingested by a number of paratenic hosts (e.g., other frogs, snakes) or directly by the definitive host, e.g. the dog.
Common in North American mammals with a wide range of definitive hosts known, including cattle, lynx, martens, skunks, bobcats, foxes, coyotes, and wolves
- Alaris americana : trematode in the family Diplostomatidae.
- All species infect carnivorous mammals, living in their small intestines as mature worms
- Development via the lungs
- Uses intermediate and paratenic hosts
Trematodes (flukes) – location
Adults
? dependent
Rumen/intestine, liver, lungs, blood, kidney
Pathology
Usually ?
Immature migration, ? disruption
Induce ? reactions
Trematodes (flukes) – location
Adults
species dependent
Rumen/intestine, liver, lungs, blood, kidney
Pathology
Usually adults
Immature migration, mechanical disruption
Induce inflammatory reactions
Trematodes – Fasciola hepatica
Final Host: ?
Mode of infection: consumes ? in the environment
Location: ?, bile ducts
Pathology: “ ? ” liver with chronic infection
Clinical signs: ?, ? jaw
Diagnosis: clinical signs + egg in ? (sedimentation) or ? antigen test
Intermediate host: ?
Trematodes – Fasciola hepatica
Final Host: ruminants
Mode of infection: consumes metacercaria in the environment
Location: liver, bile ducts
Pathology: “ PIPESTEM ” liver with chronic infection
Clinical signs: anemia, bottle jaw
Diagnosis: clinical signs + egg in feces (sedimentation) or fecal antigen test
Intermediate host: snail
