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Questions and Answers
Which characteristic is NOT typical of trematodes?
Which characteristic is NOT typical of trematodes?
- Direct life cycle (correct)
- Dorso-ventrally flattened body shape
- Presence of oral and ventral suckers
- Hermaphroditic reproductive capability
What is the term used to describe the larval stage of trematodes that develops in the snail?
What is the term used to describe the larval stage of trematodes that develops in the snail?
- Miracidium
- Rediae (correct)
- Cercaria
- Metacercaria
What is the primary mode of infection of Fasciola hepatica in its final host?
What is the primary mode of infection of Fasciola hepatica in its final host?
- Ingestion of embryonated eggs
- Vector-borne transmission via insects
- Direct penetration through the skin
- Consumption of metacercariae (correct)
Which of the following is a typical clinical sign associated with a Fasciola hepatica infection?
Which of the following is a typical clinical sign associated with a Fasciola hepatica infection?
In the life cycle of a trematode with two intermediate hosts, what stage directly precedes the adult stage in the final host?
In the life cycle of a trematode with two intermediate hosts, what stage directly precedes the adult stage in the final host?
What is the function of flame cells in trematodes?
What is the function of flame cells in trematodes?
Which subclass of Trematoda includes flukes that typically parasitize freshwater and marine molluscs?
Which subclass of Trematoda includes flukes that typically parasitize freshwater and marine molluscs?
What type of host is a freshwater snail in the life cycle of Fasciola hepatica?
What type of host is a freshwater snail in the life cycle of Fasciola hepatica?
Which term describes the type of eggs produced by trematodes?
Which term describes the type of eggs produced by trematodes?
Which of the following is a defining characteristic of helminths?
Which of the following is a defining characteristic of helminths?
Which of the following is the infective stage of Alaria americana for the second intermediate host?
Which of the following is the infective stage of Alaria americana for the second intermediate host?
What feature is commonly used in the diagnosis of trematode infections?
What feature is commonly used in the diagnosis of trematode infections?
Which of the following best describes the symmetry of trematodes?
Which of the following best describes the symmetry of trematodes?
What is the term for the disease caused by Fasciola hepatica?
What is the term for the disease caused by Fasciola hepatica?
What is the primary habitat of adult Fasciola hepatica in the definitive host?
What is the primary habitat of adult Fasciola hepatica in the definitive host?
Which of the following processes is unique to the rediae stage within a snail in the trematode lifecycle?
Which of the following processes is unique to the rediae stage within a snail in the trematode lifecycle?
What is the significance of the broad host spectrum observed in trematodes?
What is the significance of the broad host spectrum observed in trematodes?
How do metacercariae typically enter their final host?
How do metacercariae typically enter their final host?
What is the role of sedimentation?
What is the role of sedimentation?
Which of the following is a characteristic feature of trematode waste excretion?
Which of the following is a characteristic feature of trematode waste excretion?
What term is used to describe trematodes found in fish that are often called digeneans?
What term is used to describe trematodes found in fish that are often called digeneans?
Which characteristic of the Fasciola hepatica lifecycle contributes most to its widespread distribution?
Which characteristic of the Fasciola hepatica lifecycle contributes most to its widespread distribution?
In the context of trematode infections, what is 'swimmer's itch' a result of?
In the context of trematode infections, what is 'swimmer's itch' a result of?
What is the typical habitat for the metacercaria stage of trematodes?
What is the typical habitat for the metacercaria stage of trematodes?
What is the primary reason Fasciola hepatica infections lead to anemia in the final host?
What is the primary reason Fasciola hepatica infections lead to anemia in the final host?
An anthelmintic drug targets the vitelline glands of a trematode. What effect would this drug have on the parasite?
An anthelmintic drug targets the vitelline glands of a trematode. What effect would this drug have on the parasite?
What is a key characteristic that distinguishes Trematoda from Cestoda?
What is a key characteristic that distinguishes Trematoda from Cestoda?
Considering the trematode life cycle, which control measure would be MOST effective in preventing Fasciola hepatica infections in livestock?
Considering the trematode life cycle, which control measure would be MOST effective in preventing Fasciola hepatica infections in livestock?
A researcher is studying a novel trematode species and observes that its miracidia lack eyespots. What can be inferred from this observation?
A researcher is studying a novel trematode species and observes that its miracidia lack eyespots. What can be inferred from this observation?
Which of the following best describes the reproductive strategy observed in trematodes?
Which of the following best describes the reproductive strategy observed in trematodes?
What is the primary significance of 'pipestem liver' in cattle infected with Fasciola hepatica?
What is the primary significance of 'pipestem liver' in cattle infected with Fasciola hepatica?
In trematodes, what is the function of the cercariae stage?
In trematodes, what is the function of the cercariae stage?
Which of the following best describes the implications of trematodes having 'indirect' life cycles?
Which of the following best describes the implications of trematodes having 'indirect' life cycles?
Which definitive host is commonly affected by the liver fluke Amphimerus?
Which definitive host is commonly affected by the liver fluke Amphimerus?
Which parasite uses Dreissena polymorpha as its first intermediate host?
Which parasite uses Dreissena polymorpha as its first intermediate host?
Which trematode is known to infect the kidney?
Which trematode is known to infect the kidney?
Regarding trematode infections, how can definitive and final hosts be related?
Regarding trematode infections, how can definitive and final hosts be related?
Why are digenean trematodes often found in birds near bodies of water?
Why are digenean trematodes often found in birds near bodies of water?
What can be interred from a trematode egg that does not hatch?
What can be interred from a trematode egg that does not hatch?
Flashcards
Helminths
Helminths
Parasitic worms, large and multicellular.
Phylum Platyhelminthes
Phylum Platyhelminthes
Flatworms; includes trematodes, cestodes, and turbellarians.
Class Cestoda
Class Cestoda
Tapeworms.
Class Trematoda
Class Trematoda
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Trematodes
Trematodes
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Digenea
Digenea
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Aspidogastrea
Aspidogastrea
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Fasciola hepatica
Fasciola hepatica
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Fasciolosis/iasis
Fasciolosis/iasis
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Trematode characteristics
Trematode characteristics
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Trematode life cycles
Trematode life cycles
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Trematode Location
Trematode Location
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Indirect life cycle
Indirect life cycle
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Miracidium
Miracidium
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Rediae
Rediae
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Cercaria
Cercaria
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Metacercaria
Metacercaria
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Fasciola hepatica Pathology
Fasciola hepatica Pathology
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Fasciola hepatica intermediate host
Fasciola hepatica intermediate host
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Common clinical signs of fasciola hepatica
Common clinical signs of fasciola hepatica
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Study Notes
- Helminths are parasitic worms that are large and multicellular
- Helminths include a few phyla, many of which are unrelated phylogenetically but share superficial similarities like being vermiform or worm-like
Helminth Classes
- Nematoda is the phylum of roundworms
- Platyhelminthes is the phylum of flatworms
- Cestoda is a class in the phylum platyhelminthes consisting of tapeworms
- Trematoda is a class in the phylum platyhelminthes consisting of flukes that are endoparasites
- Monogenea is a class in the phylum platyhelminthes consisting of skin flukes that are ectoparasites
- Turbellaria is a class in the phylum platyhelminthes consisting of free-living flatworms and some parasitic forms
- Acanthocephala is the phylum of thorny-headed worms
- Annelida is the phylum of segmented worms, but are not parasitic as they are leeches
Trematoda
- Trematodes (flukes) are dorso-ventrally flattened and leaf-like
- Trematodes (flukes) use oral and ventral suckers for attachment and feeding
- Trematodes (flukes) are hermaphroditic but can cross-reproduce
- Trematodes (flukes) have large operculate eggs where sedimentation occurs
- Trematodes (flukes) do not have direct life cycles
- Most Trematodes (flukes) typically have a broad host spectrum, except for gastropod 1st intermediate host
- Trematodes (flukes) do not have an anus, waste material is egested through the mouth, and via specialized cells known as flame cells
- Trematodes (flukes) can be located in the rumen/intestine, liver, lungs, blood, and kidney
- Trematodes (flukes) pathology is dependent on the species
- Trematodes (flukes) pathology is usually adults
- Trematodes (flukes) immature migration causes mechanical disruption
- Trematodes (flukes) induce inflammatory reactions
Trematode Lifecycle
- Trematodes (flukes) have an indirect life cycle that includes one intermediate host
- The trematodes (flukes) final host is an adult
- The trematodes (flukes) egg hatches in an environment to become a miracidium
- The trematodes (flukes) intermediate host consists of rediae and cercaria
- The trematodes (flukes) cercaria turns into metacercaria in an environment
- The trematodes (flukes) immature adult turns into an adult
- The trematodes (flukes) final host consumes metacercaria
Fasciola hepatica
- Fasciola hepatica, also known as the common liver fluke or sheep liver fluke
- Fasciola hepatica is a parasitic trematode of the class Trematoda, Phylum Platyhelminthes
- Fasciola hepatica infects the liver of various mammals, including humans
- Fasciola hepatica has a global distribution and is an important parasite of sheep and cattle
- Fasciola hepatica final host is ruminants
- Fasciola hepatica intermediate host is snails
- Fasciola hepatica mode of infection occurs when metacercaria is consumed in the environment
- Fasciola hepatica are located in the liver and bile ducts
- Fasciola hepatica pathology causes the liver to have a "pipestem" appearance due to chronic infection
- Fasciola hepatica clinical signs include anemia, and bottle jaw
- Fasciola hepatica is diagnosed via clinical signs and egg in feces via sedimentation or a fecal antigen test
Trematode Lifecycle with 2 intermediate hosts
- The adult is the final and definitive host
- Eggs are released into the environment, where miracidium hatch
- Rediae emerge as an intermediate host in the snail -- 1st intermediate host
- Cercaria emerges again into the environment
- Metacercaria occurs in the 2nd intermediate host, paratenic host, or environment
- Young adults mature to adult form as the final and definitive host
- Final/definitive host consumes metacercaria from 2nd intermediate host, paratenic host, or the environment.
Alaria americana
- Alaria americana is a trematode in the family Diplostomatidae
- Alaria americana all species infect carnivorous mammals, and live in their small intestines as mature worms
- Alaria americana develops via the lungs
- Alaria americana utilizes intermediate and paratenic hosts
Cercarial Dermatitis
- Swimmer's 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
- Schistosoma is a genus of trematodes, and is commonly known as blood flukes
- Schistosoma are parasitic flatworms
- Schistosoma is responsible for a highly significant group of infections in humans called schistosomiasis
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