Cestoda Flashcards
Where do the larval stages of Taenia hydatigena locate?
Larval stage called Cysticercus tenuicollis
They develop in the peritoneum of cattle, sheep, goats, pigs (rarely horses)
What is the effect of the presence of cysticerci of T. hydatigena at slaughter?
Condemnation
Cysticercus pisiformis are the larval stages of what Taenia species? And where do they develop in their host?
Taenia pisiformis
Liver and peritoneum of rabbits
Where do the larval stages of Taenia ovis locate?
Cysticercus ovus develop in the muscle of sheep and goats
Adult Taenia spp live in the small intestine of the host (usually for up to one year) how many proglottids (containing eggs) will they shed daily?
2-3 gravid proglottids
How do the intermediate hosts of Taenia get infected? (sheep, cattle, rabbits, humans etc)
Ingestion of eggs or gravid proglottids
Regarding Taenia species: the oncospheres in the small intestine of the intermediate hosts are released from the eggs. What happens next?
They penetrate the intestinal wall and make their way to the organ of predilection for their species (liver, peritoneum, muscle etc.) where they will develop into mature cysticerci.
How do the definitive hosts (dog, wolf, fox, cat etc.) of Taenia species get infected?
Ingestion of tissue that contain mature cysticerci
The prevalence of Taenia infections in dogs depends on what?
How available viscera from slaughtered livestock or hunted animals (rabbits) are to the dogs.
What are the clinical signs associated with Taenia species in dogs and cats?
Infestations usually not harmful to the DH; however, heavy infections may see non-specific abdominal symptoms like diarrhoea, constipation, unthriftiness and a somewhat pot-bellied appearance.
How are you going to diagnose an infection with Taenia spp.?
Identification of proglottids (longer than wide with one genital pore) in the faeces/environment/coat or visualisation of eggs in the faeces.
Immunodiagnosis or detection of DNA in the faeces
What is the significance of Taenia eggs in comparison to Echinococcus eggs? Describe the eggs.
They cannot be distinguished from each other.
30-40um, circular or oval, brown with striated embryophore and contain an oncosphere (hexacanth embryo)
How are you going to treat infections with Taenia spp?
Fen-me-flubendazole, Nitroscanate, Praziquantel or Epsiprantel
Would you say that denying dogs access to potentially infected carcasses with Taenia spp will contribute significantly to the control of this parasite?
Yes
What is cystic echinococcosis (CE) caused by?
Larval stages of Echinococcus granulosus
What is the morphology of the adult stages of E. granulosus?
2-7mm long and can contain up to 6/7 proglottids
Scolex with rostellum and 4 suckers
The last proglottid is gravid and the one before that is mature
30-50um, circular/oval, brown eggs with a striated embryophore are from which species?
E. granulosus and T. spp (they are indistinguishable)
What are the definitive hosts of E. granulosus? And how do they become infected?
Dog, wolf, dingo, coyote, jackal, fox (not the domestic cat)
They get infected by ingesting viscera of IH that contain fertile cysts
What are the intermediate hosts for E. granulosus? And how do they get infected?
Sheep, cattle, horses, camels, deer, pigs, rabbits, kangaroos, humans, monkeys etc…
Become infected by ingesting eggs (larvae commonly develop in the liver and lungs)
What is the structure of E. granulosus cysts?
Bladder with two layers (germinal layer and laminated layer)
Metacestode surrounded by adventitial layer
Daughter cysts may develop
How can humans get infected with E. granulosus?
Contact with an infected DH (eggs can be on dog coat)
Ingestion of vegetable, salads, fruit etc. contaminated with eggs
Drinking water contaminated with eggs (from faeces)
In terms of epidemiology, how do Tasmania and New Zealand differ from mainland Australia regarding E. granulosus infections?
Tasmania and NZ have implemented 30 years of hydatid control and are on the point of declaring themselves ‘provisionally hydatid free’
What two species of animal on mainland Australia were the key to transmission success of E. granulosus?
Dingoes and Macropods
When are majority of infections of E. granulosus seen in the IH?
At slaughter
Clinical signs if any are specific to the organ affected with cysts
Infections with hundreds of E. granulosus parasites might be tolerated without any clinical signs in the definitive host. True or False?
False. Thousands of parasites can be tolerated by the DH without clinical signs.
How are you going to diagnose an infected definitive host of E. granulosus?
Faecal examination (has limitations, human safety!)
Immunodiagnosis (antigen in faeces, antibodies in serum)
Detection of copro-DNA
Direct examination of intestine at PM (human safety!)
What drug/s will you use for the treatment of infections with E. granulosus?
Praziquantel every 5-6 weeks
What actions should be undertaken to prevent infection with E. granulosus?
Do not feed dogs offal or leave carcasses laying around
Reduce the number of stray dogs and remove from farms/abattoirs
Basic hygiene and wash fruit and vegetable well
What is the most common tapeworm of the dog in many parts of the world?
Dipylidium caninum
Where does Dipylidium caninum locate and how will you identify it?
Small intestine of dog, cat, fox, human (children)
Retractable rostellum with 3-5 rows of hooks, gravid proglottids are longer than wider with two genital pores
The gravid proglottids will contain up to 150 egg capsules. What is the most distinguishing feature of Dipylidium caninum egg capsules?
Resemble cucumber seeds
What will ingest the eggs of Dipylidium caninum?
Fleas
Will you see clinical signs in Dipylidium caninum infestations?
Commonly no obvious clinical signs
May drag anus on the ground –> alopecia
Abdominal pain, haemorrhagic enteritis seen commonly in infections with more than 100 parasites
What is the first step to controlling an infection with D. caninum?
CONTROL THE FLEAS (then treat D. caninum)
What is the scientific name for the zipper worm?
Spirometra erinacei
Where do adult Spirometra worms locate and in what host?
Small intestine of cat, fox and dog
What do the eggs of Spirometra erinacei look like?
Yellow, asymmetrical and operculated
What are the two larval stages of Spirometra erinacei?
Procercoid larvae (cyclops spp) Plerocercoid larvae (frogs, reptiles, birds, mammals, but not fish)
What is the lifecycle of Spirometra erinacei?
Sorry guys, too complicated for this but definitely have a look at it :)
What is sparganosis?
Infection with plerocercoid larvae of the genus Spirometra
How can humans get infected with Sparganum and subsequently develop sparganosis?
Drinking water containing copepods with procercoid larvae
Ingesting meat from hosts containing plerocercoid larvae
By pressing flesh of infested frog as a poultice to ulcers, wounds or sore eyes (humans are paratenic hosts)
Which drug is the only one that will treat infections with all four species of tapeworm?
Praziquantel (Droncit)
What are the four main tapeworm species found in dogs and cats?
Taenia spp
Echinococcus spp
Dipylidium caninum
Spirometra spp
