03. Cestodes: Order cyclophyllidea, Family Taeniidea ( Genera Taenia, Echinococcus) Flashcards
Who is the only definitive host of the beef tapeworm? What is the scientific name of the beef tapeworm?
Humans are the only DH
Taenia saginata
Where do the adult tapeworms of Taenia saginata occur in humans?
Small intestine
Where do the oncospheres of Taenia saginata hatch from the egg in the host?
In the small intestine, it penetrates the intestinal wall and enters the blood stream
How does a human acquire T. saginata? what life cycle stage does it acquire it at?
Raw or poorly cooked beef containing: CYSTICERCI
The oncosphere became a cysticerci in the muscle before the animal was killed for eating
What is the process once the cysticercus of Taenia saginata is ingested by the DH/human?
Once in the small intestine, the scolex evaginates from the cysticercus and attaches to the wall of the ileum, to begin strobilation
When does the adult Taenia saginata reach maximum maturity and length in the DH?
in 3 moths
Can cattle become infected with T. saginata by ingesting the cysticerci?
NO
Can humans harbour the metacestodes of T. saginata?
NO - the eggs can only hatch in the cow
Are eggs of the family Taeniidae morphologically different?
NO - not used for diagnosis
Where does the cysticercus of T. saginata develop?
in the muscle of the cow
Does Taenia saginata adult worm have hooks?
NO - 4 suckers and lacks hooks
Is the Taenia saginata genital pore common or separate?
common
How do we differentiate between T. saginata and T. solium?
By looking at the gravid proglottids - T. saginata has ≥15 branches (usually around 20-25)
while T. solium has 14 or less (usually around 14) and they are shorter branches
What is the taxonomy of T. solium?
Order Cyclophyllidea
Family Taeniidae
Genera Taenia
Species solium
What is the taxonomy of T. saginata?
Order Cyclophyllidea
Family Taeniidae
Genera Taenia
Species saginata
What are the hosts of Pork tapewirm (T. solium)
Humans are the only definitive host and pigs are intermediate host - no reservoir hosts for this parasite
Which is more dangerous, T. solium or T. saginata? and why?
T. solium, because humans can also be the accidental intermediate host, whereby eggs are ingested and this leads to the disease cysticercosis
How do T. solium and T. saginata eggs compare?
They are morphologically indistinguishable - not used for diagnosis
What is found in the eggs of Family Taeniidae?
- Surrounded with a thick radially striated brown embrophore
- Inside is an oncosphere with 6 hooklets
Who has hooks between T. saginata and T. solium?
T. solium
What is the morphology of the adult T. solium?
Scolex with 4 suckers and 2 circles of hooks
What is the condition that arrises if the DH (human) becomes the accidental IH and ingests the eggs of T. solium?
Cysticercosis
Does cysticercosis only apply to humans?
NO
How is the infection passed in T. solium? (pigs)
by ingesting eggs or gravid proglottids that originates from the feces of an infected individual
Where do the oncospheres hatch out of the egg in T. solium?
The pig ingests embryonated eggs, and in the pig small intestine, the egg hatches to yield the oncosphere and it will enter circulation
What is the disease of cycts in the human brain?
Neurocysticercosis
What is the clinical diagnosis of T. solium eggs and/or proglottids in human feces?
taeniasis
Name some types of cysticercosis infections
occular cysticercosis
neurocysticercosis
cardio cysticercosis
Is treatment of cysticercosis usually effective with anti-parasitic drugs? Of the adult worm?
Treatment suboptimal for cysticercosis
Treatment very effective for the adult worm
How does Praziquantel work?
Increases the permeability of the worm’s membranes toward calcium ions
What is the taxonomy of E. granulosus?
Order Cyclophyllidae
Family Taeniidae
Genera Echinococcus
Species granulosus
What is the taxonomy of E. miltilocularis?
Order Cyclophyllidae
Family Taeniidae
Genera Echinococcus
Species multilocularis
Is Echnococcus big or small relative to other worms?
small (one of the smallest)
What is special about Echonococcus spp.?
They only have a scolex, a neck and one of each stage of maturation of proglottid (immature, mature and gravid)
What are the DH of Echinococcus?
domestic dogs and other Canidae
What are the IH of Echinococcus?
sheep and other hebivores
How does Echinococcus effect humans?
They are susceptible to the juvenile stage of the parasite, which may develop into a large, fluid filled cyst (hydatid cyst)
What is the disease associated with human exposure to the juvenile stage of Echonococcus?
Hydatid disease (characterized by hydatid cysts)
Describe a hydatid cyst
- Instead of having cysticerci, they have hydatid cysts, which contain multiple brood capsules containing the protoscolices.
- the cyst is filled with hydatid fluid (HF) and consists of multiple layers
What is another name for Hydatid disease?
Echinococcosis
T/F E. multilocularis occurs in the Northern hemisphere
true
What is caused by Echinococcus granulosus?
cystic echinococcosis
What is caused by Echinococcus multilocularis?
alveolar schinococcosis
What stage of development of cestodes causes Human echonococcosis?
The larval stages
What is the most common form of treatment for Echinococcosis?
Surgery, although it is not always 100% effective + medication postoperatively
How does albendazole work?
Albendazole causes degenerative alterations in the tegument and intestinal cells of the worm by binding to tubulin, which inhibits its assembly into microtubules
