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62 Cards in this Set

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  • Back
Describe the morphological characteristics of cestodes.
Adults in the SI, ILC generally (only 2 exceptions). Don't have a body cavity, organs supported by a cellular parenchyma. Surface of the cestode covered by tegument, which allows nutrient absorption and waste excretion. Also have a flame cell system. Have a scolex, neck and strobila. Each segment is hermaphrodite.
What is protandry?
Male organs develop first in the cestode segments.
Describe the eggs of the Cyclophyllidea.
Eggs aren't released until the uterus is full, it then breaks off and passes out. Cyclophyllidean eggs have a thin outer membrane, the next layer is a thick embryophore enclosing the hexacanth embryo
Describe the eggs of the Pseudophyllidea.
Gravid segments remain attached, so eggs pass out through the uterine pore of the segment and are passed. Eggs have a shell with a single operculum. A period of development outside the host is necessary before the embryo (known as a coracidium) is developed.
Describe the scolex of Cyclophyllidea.
4 suckers present, sometimes armed with hooks. Most spp have a rostellum armed with one or more rows of hooks.
Describe the reproductive organs of Cyclophyllidea.
One or two sets of male and female organs may be present. Males have a protusable cirrus which protudes through the genital pore (on the lateral side). Gravid proglottids are dropped off
Describe the scolex of Pseudophyllidea.
Has two longitudinal sucker grooves (bothria). NO HOOKS AND NO ROSTELLUM.
Describe the reproductive organs of Pseudophyllidea.
Only one set per segment. Similar to Cyclophyllidea, but the uterus opens at the uterine pore which is located in the midline of the segment. Eggs once fertilized don't accumulate but are discharged.
What is the receptaculum seminis?
Holding facility for sperm.
What are the vitellaria and Mehlis' glands?
They add the yolk and shell material to the eggs.
Fluid-filled bladder-like cyst into which one protoscolex is invaginated. Occurs in VERTEBRATE IH only
Similar to cysticercus, but the cyst doesn't contain fluid and closely enfolds one protoscolex. Occurs in INVERTEBRATE IH only.
A fluid-filled cyst lined by a germinal membrane from which are budded many protoscolices. These remain attached to the germinal layer and are not grouped in capsules. Occurs in VERTEBRATE IH only.
Hydatid cyst
A fluid-filled cyst lined by germinal membrane, and has a thick outer layer. The germinal membarne produces may protoscolices which bud off and contain a germinacl membrane of their own (brood capsules). Often contain hydatid sand in the bottom. Occurs in VERTEBRATE IH only.
What is hydatid sand?
Single solices, brood capsules and daughter cysts
What is special about the cyst formed in Echinococcus multilocularis
Similar to a hydatid cyst, but the thick outer layer is absent. The cyst wall proliferates new cysts outside as well as protoscolices inside. Metastasizes very easily.
What gut factor causes evagination of the protoscolices?
Bile salts
What stage of a cestode is passed in the faeces of the DH?
Gravid segment containing infective eggs.
What stage is infective for the IH?
Egg containing a hexacanth embryo.
What stage is infective for the DH?
Protoscolex contained in a cyst of some type.
Describe the morphology of the family Taeniidae.
Hint: its a Cyclophyllidae
Scolex has 4 suckers not armed by hooks and a fixed rostellum with two rows of hooks. One set of genitalia per segment, genital pores alternate down each side, the gravid segments are longer than wide and the eggs persist in the uterus. Larvae are everything BUT A CYSTICERCOID.
Taenia hydatigena
Usually less than a metre long. DH are dogs, IH are sheep, cattle, pigs, deer. Cysticercus tenuicollis larva. Cysts found in the abdominal cavity of the IH. Egg hatches in the SI of the IH, migrates in the portal blood to the liver, migrates around in the liver, breaks through and falls into the abdominal cavity.
Taenia ovis
Usually less than a metre long. DH are dogs, IH are sheep/goats. Cysticercus ovis larva. Cysts found in the IM connective tissue of the IH. Often in the heart and diaphragm. No involvment of the liver.
Taenia taeniaeformis
About 60cm long. DH are cats, IH are mice and rats. Cysicercus fasiolaris larvae - modified cysticercus. Cysts are found in the liver of the IH.
Taenia saginata
About 25cm long. DH are humans, IH are oxen. Cysticercus bovis larvae. Cysts are found in the IM connective tissue, often in the tongue, heart and masseter muscles.

NB very distinctive in that the scolex and larval protoscolexhave no rostellum and no hooks.
Taenia solium
Up to 7 metres long. DH are humans, IH are pigs. Cysticercus cellulosae larvae. Cysts are found in the IM connective tissue.
What is unique about Echinococcus granulosus - the hydatid tapeworm - compared to other members of Taeniidae?
Echinococcus is very small, only 4-6mm, others are well over a couple of metres.
Echinococcus granulous
DH are dogs and its close relatives, IH are normally ungulates. Cyts usually form in the liver and lungs. Distinguished from other cestode cysts by having a thick laminated layer. Layers in the cyst are germina, laminated and adventitious layer. Human infection occurs from the ingestion of faeces from infected dogs, the cyts in animals aren't dangerous.
What are the morphological characteristics of Dilepididae?
About 20cm long. DH are cats and dogs, IH are larvae of fleas or lice. Scolex has a retractable rostellum armed with 4-6 rows of thorn shaped hooks. Segments have duplicate sets of genitalia with a genital pore both sides on each segment. Gravid segments contain eggs in capsules.
How would you differentiate Dipylidium caninum from Taeniidae?
The rows of hooks on Dipylidium.
What larvae does D. caninum produce?
Cysticercoid, which persisit in the flea or louse as it moults to the adult. DH becomes infected by ingesting the IH.
What are the morphological characteristics of Anoplocephalidae
DH are ruminants and horses, IH are free-living pasture mites.
Anophocephala perfoliata
Adults found in the ileocaecal junction of horses. About 8-10 cm. Looks rather like short pieces of fettucini. Doesn't have a rostellum, and doesn't have hooks.
Adults found in the SI of ruminants. Scolex has no rostellum and no hooks. Larvae are cysticercoid.

M. expansa and M. benedeni infect sheep, goats and cattle.
Davainea proglottina
The most pathogenic cestode of poultry. Only 4mm or so, IH are slugs/snails.
Raillietina spp
Not as pathogenic as Davainea. IH are beetles, ants, cockroaches and flies.
Describe the differences between Pseudophyllidea and Cyclophyllidea.
The scolex has two longitudinal sucking grooves (bothria) instead of 4 suckers. There are no hooks. The genital pore is centrally placed in each segment, and the eggs are shed while the segments are still attached. Eggs are operculate and resemble trematode eggs, but contain a coracidium with 6 hooks. Their life cycle involves 3 larval stages (coracidium, procercoid, plerocercoid) and 2 intermediate hosts (the first is an invertebrate, the second a vertebrate)
What does develops inside a pseudophyllidea egg if it reaches water?
A coracidium (a round ciliated thing). Hatches in water in response to light. Swims around looking for an aquatic crustacean.
What is the stage that develops in the crustacean?
Procercoid, which is a solid bodied larvae with 6 hooks.
What is needed for the procercoid to develop further?
The crustacean must be eaten by a second IH (fish, amphibian or reptile) and then the procercoid will develop into a plerocercoid usually in the hosts muscles.
Describe the pleurocercoid.
Elongated with a scolex invaginated at one end.
Diphyllobothrium latum
First IH is a freshwater crustacean, second is a freshwater fish. DH are humans, dogs and cats. Occurs commonly in countries which eat raw, dried or smoked fish. NOT IN NZ.

Way to remember, latum is a brand of pickled herring.
Spirometra erinacei
First IH is a FW crustacean, second IH are a number of vertebrates inc. frogs, lizards, snakes, rodents, marsupials, pigs etc. DH are dogs and cats (and other canid relatives). Humans can become infected (known as sparganosis by eating undercooked pork.
Describe the morphology of the phylum Acanthocephala.
Commonly known as thorny headed worms. Adults are in the small intestine. They look like a nematode, but have a thick tegument and no alimentary tract. Anterior end has a hooked proboscis. SEXES ARE SEPARATE. Fertilised eggs are discharged containing a thick shell.
Describe the LC of Acanthocephala.
LC involves crustaceans as IH for aquatic life or seabirds. IH are cockroaches and such for terrestrial DHs.
Macracanthorhynchus hirudinaceus.
IH are dung beetles, cockroaches etc. DH are pigs. Adults in the SI. Females are very large
Describe the general morphology of digean termatodes.
Unsegmented, most are flattened dorso-ventrally, some are fleshy. Body is covered by a complex tegument containing spines. No body cavity, all organs are supported by a cellular parenchyma. Oral sucker for feeding, ventral sucker for attachment. Alimentary system, containing two blind-ending caeca. NO ANUS. Regurgitation of waste, osmoregulation by flame cells.
Describe the reproductive systems of digean trematodes.
All (except Schisotosomatidae) are hermaphrodites. Males have 2 testes, females have 1 ovary. All trematode (except Schistostomadtidae) have an operculum at one end.
Describe the digean LC.
ALWAYS INDIRECT, with a snail (often aquatic) as the first IH. Some spp have have second and third IHs.
What are the stages in the digean trematode LC.
Egg, miracidium, sporocyst, redia, cercaria, metacercaria.
What do digean trematode eggs contain when laid?
Describe the sporocyst.
Sac-like structure lined by germinal cells which produce redia, which burst through the sporocyst wall.
Describe the redia.
Elongated, has a mouth and simple gut. Motile and migrates to the hepato-pancreas of the IH. Cercaria produced leave via a birth pore.
Describe the cercaria.
Have a body and tail, look somewhat like sperm. The body has suckers, a gut and flame cells. The cercaria leave the snail and infect the DH once they are metacercaria.
Describe the three situations where encystment occurs.
On vegetation, on or in the first IH, on or in the second IH.
How does Schisotsomatidae infect its DH?
Cercaria penetrate the skin.
What are almost all digean LCs dependent on?
Which trematode makes ants go all crazy?
Dicrocoelium dendriticum (not in NZ).
Trematodes are hightly IH host specific. True or False?
Describe the general morphology of the family fasciolidae.
Quite large, flat, leaf-like flukes often with an anterior conical projection. Caecae and gonads are much branched. Adults inhabit the bile duct or intestine.
Fascioloides magna
Bile ducts of ruminants and horses in the USA/Europe.
Fasciolopsis buski
SI of man in S.E. Asia.