PARA 410 Lecture Notes - Lecture 3: Taenia Saginata, Taenia Solium, Cestoda
12 Jun 2018
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Parasitology – lecture 03 – Taeniidea (January 11th 2018)
Slide 3 – Taenia saginata
- Beef tapeworm – humans are the only definitive host and cattle are the only intermediate host
- Adult tapeworms occur in humans in the small intestine
- Can grow between 4-8 meters long
Slide 4 – Life Cycle
- Definitive host grows and matures to make gravid proglottids. The proglottids are released through strobilation in
the faeces. The gravid proglottids contain the embryonated eggs and they will burst, releasing the eggs in the
environment.
- If this occurs in grazing areas, the cows can take-up the eggs while eating (because the eggs are in the soil)
- The eggs can hatch in the intestine of the cow
- The cyticercus will develop in the tissues – can end up in steak and if they are not cooked well and are ingested →
will develop and become sexual in the human small intestine
- Reaches maximal maturity and length within 3 months
find more resources at oneclass.com
find more resources at oneclass.com
Slide 5 – Life cycle (from the slides)
- Gravid proglottid ruptures on land during drying and releases eggs into soil
- Grazing cow (intermediate host) must ingest the eggs
- Oncosphere hatches from egg in cow small intestine, penetrates intestine and enters circulation
- Oncosphere reached the skeletal muscles and becomes a cysticercus
- Human eats raw or poorly cooked beef containing cysticerci
- Scolex evaginates, attaches to wall of ileum, and begins strobilation
- Adult reaches maturity and maximal length in 3 months
Slide 6 – Taenia saginata
- Cattle cannot become further infected with adult parasites if they accidentally ingest cysticerci
- Humans cannot harbour the metacestodes, since Taenia saginata eggs will only hatch in the stomach of cows
o This is not the case for Taenia solium (pork tapeworm)
Slide 7 – Taenia spp.
- The release of eggs of the family Taeniidae are morphologically indistinguishable
- They are not used for diagnosis
- The eggs are spherical (31-43µm diameter) with a thick radially striated brown embryophore
- Inside each is an oncosphere with 6 hooklets
o Can see better under the microscope
Slide 8 – Taenia saginata
- The cysticercus develops in the muscle
- The scolex is invaginated
- T. saginata doesn’t have hooks like the pork tapeworm
- The beginning of the development of the adult worm is the evagination of the scolex from the cysticercus
find more resources at oneclass.com
find more resources at oneclass.com
→ The small scolex is invaginated into the cysticercus (in the tissue of the intermediate host)
→ The scolex evaginates from the cysticercus (in definitive host)
Slide 9 – Taenia saginata
Adult morphology:
- Scolex contains four suckers and lacks hooks
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Parasitology lecture 03 taeniidea (january 11th 2018) Beef tapeworm humans are the only definitive host and cattle are the only intermediate host. Adult tapeworms occur in humans in the small intestine. Definitive host grows and matures to make gravid proglottids. The proglottids are released through strobilation in the faeces. The gravid proglottids contain the embryonated eggs and they will burst, releasing the eggs in the environment. If this occurs in grazing areas, the cows can take-up the eggs while eating (because the eggs are in the soil) The eggs can hatch in the intestine of the cow. The cyticercus will develop in the tissues can end up in steak and if they are not cooked well and are ingested will develop and become sexual in the human small intestine. Reaches maximal maturity and length within 3 months. Slide 5 life cycle (from the slides) Gravid proglottid ruptures on land during drying and releases eggs into soil.
