Helminth Flashcards

Cestodes

Question	Answer	Article
Fill in the missing words about cestodes	A cestode (tapeworm) is a chain (strobila) of progressively maturing reproductive units called proglottids anchored at one end to the intestinal wall by a hold-fast organ called the scolex.	Link to Answer Article
What species of Taenia occur in dogs?	Taenia ovis Taenia hydatigena Taenia pisiformis Taenia multiceps Taenia serialis	Link to Answer Article
Describe the features of a cysticercus	Fluid filled bladder, containing a single invaginated head (protoscolex) - seen as a white blob on the wall of the cyst	Link to Answer Article
*In which host(s) would you expect to find the cysticercus of T. hydatigena* and where in the host might it be found?**	Sheep (mostly)' Cattle Pigs *Found in the peritoneal cavity*	Link to Answer Article
What is the difference between a coenurus and a cysticercus?	A coenurus is a fluid filled bladder with multiples (dozens) of inverted scolices attached to the wall Whereas the cysticercus has only a single inverted scolex.	Link to Answer Article
How does the distribution of hydatid cysts differ in sheep, horses and humans?	Sheep = most are in the lungs with smaller numbers in the liver Horses = nearly all are in the liver Humans = most are in the liver, with some in the lungs and a few elsewhere	Link to Answer Article
What tapeworms occur in the cat?	Taenia taeniaeformis Dipylidium	Link to Answer Article
*Why is it so difficult to prevent many cats from becoming re-infected with T. taeniaeformis?*	The intermediate hosts are mice and other small mammals that are hunted	Link to Answer Article
*Where in the host (horse) would you expect to find Anoplocephala?*	Ileo-caecal junction	Link to Answer Article
*Why are Anoplocephala* eggs rarely seen on routine faecal examination?**	They are dense structures and do not always float in the flotation media used in routine diagnosis	Link to Answer Article
*Why is it so difficult to prevent grazing horses from becoming re-infected with Anoplocephala?*	The intermediate hosts are ubiquitous free-living pasture mites	Link to Answer Article
Describe the appearance of Moniezia	Long tapeworm (up to 2m) Segments much wider than they are long	Link to Answer Article
*Why is T. solium* more dangerous to human health than T. saginata?**	If T. solium eggs get into the human small intestine, they will hatch and cysticerci can establish in the musculature and CNS. This does not happen with T. saginata.	Link to Answer Article

Trematodes

Question	Answer	Article
*What are the most diagnostic features of the Fasciola hepatica* egg?**	Oval and brown Granular contents Operculum ('trap-door') at one end Double the size of a typical strongyle egg	Link to Answer Article
Fill in the missing words about Lymnaea truncatula	Lymnaea truncatula is the intermediate host for (Fasciola hepatica). It is found in muddy areas, and feeds on slimy green algae. It has a brown-black shell with 5-6 spirals.	Link to Answer Article
What is the post mortem appearance of the liver in cases of acute fasciolosis?	Haemorrhagic tracts Enlarged, pale and friable	Link to Answer Article
What time of year do the clinical signs of chronic fasciolosis become apparent?	January - March	Link to Answer Article
*Why is Dicrocoelium* less pathogenic than Fasciola?**	Migrates directly up the common bile duct and therefore does NOT migrate through the parenchyma (unlike Fasciola)	Link to Answer Article
*Is Paramphistomum* found in the UK?**	Rare in the UK, but can cause severe losses in ruminants in the wet tropics	Link to Answer Article
What is the major cause of pathogenicity in schistosome infections?	The eggs have a spike to help them work their way into the intestine or urinary bladder This causes mechanical damage and inflammatory responses that are exacerbated by antigens released by the eggs	Link to Answer Article

Nematodes

Question	Answer	Article
What is the function of the bursa in bursate nematodes?	Clasp the female during mating	Link to Answer Article