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What are the intermediate hosts for Hymenolepis nana?
What are the intermediate hosts for Hymenolepis nana?
Beetles and fleas.
Describe the life cycle of Hymenolepis nana, including its intermediate hosts and mode of infection.
Describe the life cycle of Hymenolepis nana, including its intermediate hosts and mode of infection.
Hymenolepis nana eggs, immediately infective when passed with stool, can't survive more than 10 days in the environment. Beetles and fleas can serve as intermediate hosts. Oncospheres contained in the eggs are released upon ingestion. Oncospheres penetrate the intestinal villus and develop into cysticercoid larvae. Cysticercoids return to the intestinal lumen, evaginate their scoleces, and attach to the intestinal mucosa. Adult worms reside in the ileal portion of the small intestine and produce gravid proglottids. Eggs are passed in the stool through the genital atrium of proglottids or when proglottids disintegrate. Internal autoinfection is an alternate mode of infection. The life span of adult worms is 4 to 6 weeks, but internal autoinfection allows the infection to persist for years.
Describe the structure of a tapeworm and its main organ of attachment to the host.
Describe the structure of a tapeworm and its main organ of attachment to the host.
Tapeworms are segmented flatworms called Cestodes that lack a digestive tract or circulatory system. The scolex is the main organ of attachment to the host and is less than 2mm long with four cup-shaped suckers. The head also has hooks, suckers, or grooves for attaching to the host's intestine.
How do oncospheres develop into cysticercoid larvae?
How do oncospheres develop into cysticercoid larvae?
What is the role of internal autoinfection in the persistence of Hymenolepis nana infection?
What is the role of internal autoinfection in the persistence of Hymenolepis nana infection?
What is the function of the neck in tapeworms?
What is the function of the neck in tapeworms?
How do Hymenolepis nana cysticercoids attach to the intestinal mucosa?
How do Hymenolepis nana cysticercoids attach to the intestinal mucosa?
What are some symptoms of tapeworm infection, and how do tapeworms infect humans and animals?
What are some symptoms of tapeworm infection, and how do tapeworms infect humans and animals?
How long is the lifespan of adult H. nana worms and what allows the infection to persist for years?
How long is the lifespan of adult H. nana worms and what allows the infection to persist for years?
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Study Notes
- Hymenolepis nana eggs are immediately infective when passed with stool.
- Eggs can't survive more than 10 days in the external environment.
- Beetles and fleas can serve as intermediate hosts for H. nana.
- Oncospheres contained in the eggs are released upon ingestion.
- Oncospheres penetrate the intestinal villus and develop into cysticercoid larvae.
- Cysticercoids return to the intestinal lumen, evaginate their scoleces, and attach to the intestinal mucosa.
- Adult worms reside in the ileal portion of the small intestine and produce gravid proglottids.
- Eggs are passed in the stool through the genital atrium of proglottids or when proglottids disintegrate.
- Internal autoinfection is an alternate mode of infection.
- The life span of adult worms is 4 to 6 weeks, but internal autoinfection allows the infection to persist for years.
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