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Questions and Answers
Why might serological tests for Echinococcus granulosus be unreliable even when a patient is infected?
Why might serological tests for Echinococcus granulosus be unreliable even when a patient is infected?
- The parasite's antigens undergo significant antigenic variation, making it difficult for serological assays to detect all strains.
- The cysts are effectively walled off from the host's immune system, limiting exposure to antigens and antibody production. (correct)
- The serological tests have low sensitivity and specificity and often cross-react with other helminth infections.
- Antibodies produced against _Echinococcus_ are rapidly cleared from the bloodstream, leading to false-negative results.
In the PAIR technique for treating hydatid cysts, what is the primary purpose of injecting a protoscolicidal agent after aspirating the cyst fluid?
In the PAIR technique for treating hydatid cysts, what is the primary purpose of injecting a protoscolicidal agent after aspirating the cyst fluid?
- To kill any remaining protoscolices and prevent the formation of new cysts from residual parasitic material. (correct)
- To reduce the risk of anaphylactic shock by neutralizing any remaining parasitic antigens within the cyst.
- To promote fibrosis and scarring of the cyst wall, thereby preventing further expansion of the cyst.
- To sterilize the cyst cavity and prevent the development of secondary bacterial infections.
What is the significance of the germinal membrane in Echinococcus granulosus cysts regarding treatment strategies?
What is the significance of the germinal membrane in Echinococcus granulosus cysts regarding treatment strategies?
- The germinal membrane triggers a severe inflammatory response, necessitating the use of corticosteroids during treatment.
- The germinal membrane is the primary site of larval development and is the target of drugs like albendazole. (correct)
- The germinal membrane prevents the entry of immune cells, making it necessary to use immunosuppressants during treatment.
- The germinal membrane secretes a fluid that neutralizes antiparasitic drugs, requiring higher drug dosages.
Why is the rupture of a hydatid cyst during surgical removal a significant concern?
Why is the rupture of a hydatid cyst during surgical removal a significant concern?
How does the lifecycle of Diphyllobothrium latum differ from that of Echinococcus granulosus in terms of intermediate hosts?
How does the lifecycle of Diphyllobothrium latum differ from that of Echinococcus granulosus in terms of intermediate hosts?
What is the primary mechanism by which Diphyllobothrium latum causes pathology in infected humans?
What is the primary mechanism by which Diphyllobothrium latum causes pathology in infected humans?
Why is consuming undercooked freshwater fish a significant risk factor for Diphyllobothrium latum infection, but not for Echinococcus granulosus?
Why is consuming undercooked freshwater fish a significant risk factor for Diphyllobothrium latum infection, but not for Echinococcus granulosus?
In endemic regions, what public health measure would be most effective in preventing the transmission of Echinococcus granulosus to humans?
In endemic regions, what public health measure would be most effective in preventing the transmission of Echinococcus granulosus to humans?
How do the clinical manifestations of hydatid cysts caused by Echinococcus granulosus vary depending on the organ affected?
How do the clinical manifestations of hydatid cysts caused by Echinococcus granulosus vary depending on the organ affected?
What structural feature differentiates Diphyllobothrium latum from other tapeworms, contributing to its unique name?
What structural feature differentiates Diphyllobothrium latum from other tapeworms, contributing to its unique name?
Flashcards
Helminth classifications
Helminth classifications
Tapeworms, flukes, and roundworms.
Diphyllobothrium latum hosts
Diphyllobothrium latum hosts
Humans, dogs, and cats.
Diphyllobothrium latum transmission
Diphyllobothrium latum transmission
Raw or undercooked fish.
Scolex
Scolex
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Neck (tapeworm)
Neck (tapeworm)
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Proglottid
Proglottid
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Definitive host of Echinococcus granulosus
Definitive host of Echinococcus granulosus
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Intermediate hosts of Echinococcus granulosus
Intermediate hosts of Echinococcus granulosus
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Accidental intermediate host of Echinococcus granulosus
Accidental intermediate host of Echinococcus granulosus
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Transmission of Echinococcus granulosus
Transmission of Echinococcus granulosus
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Study Notes
- Helminth parasites include cestodes (tapeworms), trematodes (flukes), and nematodes (roundworms).
Cestodes
- Also known as tapeworms
Diphyllobothrium latum
- A type of tapeworm, also known as the fish tapeworm.
- Definitive hosts include humans, dogs, and cats, with humans being optimal hosts.
- Freshwater crustaceans are the first intermediate hosts.
- Transmission occurs by eating raw or undercooked fish containing larval stages.
- Causes intestinal damage, leading to a disease called diphyllobothriosis.
- Diagnosed by observing operculated eggs in stool samples.
- Praziquantel is an effective treatment.
- Basic structure includes a head (scolex) with suckers (and sometimes hooks) for intestinal attachment
- Also features a neck (generative area), and a body (strobila) composed of proglottids.
- Proglottids contain both male and female gonads, making them self-fertilizing hermaphrodites.
- The life cycle begins when a human ingests undercooked fish containing larvae.
- The larva hatches in the small intestine, attaches, and matures into an adult tapeworm.
- The tapeworm produces proglottids filled with eggs, which are excreted in feces into water.
- Eggs hatch into larvae and are consumed by Cyclops (water fleas).
- Infected Cyclops are eaten by fish, completing the cycle when humans eat undercooked fish.
Echinococcus granulosus
- A type of tapeworm, also known as the dog tapeworm.
- Dogs are definitive hosts.
- Sheep and cattle are intermediate hosts.
- Humans are accidental intermediate hosts.
- The life cycle starts when dogs consume infected organs (especially liver) of sheep or cattle.
- The liver contains hydatid cysts with protoscolices (tapeworm heads).
- Inside the dog's intestines, the protoscolex matures into a tiny tapeworm.
- The adult tapeworm produces eggs, which are excreted in dog feces.
- Sheep or cattle ingest eggs from contaminated grass, leading to hydatid cyst formation in their organs.
- Humans become infected by ingesting eggs from contaminated food or water.
- Causes hydatid disease (hydatidosis).
- Most infections are asymptomatic, but large cysts can cause pressure on organs.
- Liver cysts cause abdominal pain, while cysts in lungs, brain, or eyes can cause severe symptoms.
- Cyst rupture can trigger anaphylaxis or new cyst formation.
- Diagnosis involves imaging (CT scan, ultrasound) and serology tests (though may be unreliable if cysts are intact).
- Treatment options include albendazole (effective against the germinal membrane), praziquantel (effective against protoscolices), PAIRs technique and surgical removal.
PAIRs technique
- Puncture the cyst
- Aspirate fluid
- Inject protoscolicidal agent (e.g., hypertonic saline)
- Re-aspirate the contents
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