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48 Cards in this Set
- Front
- Back
What are the physical characteristics of tapeworms in general?
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Tapeworms consist of a chain (strobila) of progessively maturing, independent reproductive units (segments or proglottids) anchored at one end to the intestinal wall by an anchor organ (scolex).
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Pseudophyllideans
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Scolex with four longitudinal grooves.
Central genital pre on each segment. Eggs and lifecyles bear some similarity to trematodes Subtropical: Spirometra |
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General characteristics of Cyclophyllideans
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Scolex with four circular suckers
Some with ‘hooks’ “armed” Most live in small intestine New segments bud off Each segment develops male and female organs INDEPENDENT Cross fertilize LATERAL genital pores “Gravid” segments may contain >100,000 eggs |
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Segments of Cyclophyllideans
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1 or 2 segments drop off daily and exit the animal
Mobile, and also excreted with feces LATERAL! Genital pore |
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Eggs of Cyclophyllideans
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A tapeworm larvae with six hooks (onchosphere) surrounded by a ‘shell’ made of numerous blocks
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Life cycle of Cyclophyllideans
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Adult tapes in final host shed segments/eggs eggs in environment swallowed onchosphere travels in blood stream to predilection site larval tapes develop (metacestodes) Intermediate host tissue eaten metacestode swallowed new infection in final host
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What are metacestodes?
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The larval stage of tapeworms.
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What are the 6 types of metacestodes?
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Cysticercus: a fluid filled bladder with one inverted scolex.
Cysticercoid: invertebrates only; reduced bladder. Coernus: like a cysticercus but has multiple inverted scolices. Strobilocercus: cat tapeworm Taenia taeniaeformis; like a cysticercus but single scolex is attached to a bladder by a chain of segments. |
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Hydatid cyst
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fluid filled bladder
Inverted solices Hydatid fluid and hydatid sand, usually walled off by fibrous tissue |
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Alveolar cyst
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Similar to hydatid cyst but daughter cysts bud off the external surface and the cyst expands by infiltrating through tissue like a tumor
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Echinococcus
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Taeniid tapeworm
Important zoonosis Hydatid cyst can develop in humans as well as in many other animals Can grow to ping pong size in sheep, tennis ball in horse, and a soccer ball in man. |
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Life cycle of Echinococcus granulosus
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Final host is dog, fox, or other canid
Small worm 0.5cm long Scolex is deeply burried in intestinal crypt PPP 6 weeks 1 gravid segment passed each week LOW biotic potential Intermediate host infected by ingesting eggs Half the size of a ‘strongyle egg’ Metacestode is a hydatid cyst |
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Echinococcus multiocularis
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Final host is fox
Simlar to E. granulosus, however: Metacestode is a alveolar (or mutilocular) cyst Particularly dangerous as invades tissues by ‘budding off’ externally Ie: will infiltrate the liver like an invasive tumor and be inoperable |
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Taenia saginata:
Final host, intermediate host, metacestode? |
Final host: human
Intermediate host: cattle Metacestode: cysticercus in muscle |
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Taenia solium:
Final host, intermediate host, metacestode? |
Final host: human
Intermediate host: pig Metacestode: cysticercus in muscle |
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Taenia ovis:
Final host, intermediate host, metacestode? |
Final host: dog
Intermediate host: sheep Metacestode: cysticercus in muscle |
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Taenia hydatigena:
Final host, intermediate host, metacestode? |
Final host: dog
Intermediate host: sheep and other ruminants Metacestode: cysticercus in peritoneum |
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Taenia pisiformis:
Final host, intermediate host, metacestode? |
Final host: dog
Intermediate host: rabbit Metacestode: cysticercus in peritoneum |
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Taenia multiceps:
Final host, intermediate host, metacestode? |
Final host: dog
Intermediate host: sheep, rabbit Metacestode: coernus in skull |
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Taenia serialis:
Final host, intermediate host, metacestode? |
Final host: dog
Intermediate host: sheep, rabbit Metacestode: coernus in inter-muscular connective tissue. |
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Taenia taeniaeformis:
Final host, intermediate host, metacestode? |
Final host: cat
Intermediate host: mice, rodents Metacestode: strobilocercus in liver |
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How are humans infected by T. saginata?
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By eating undercooked beef.
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Is T. saginata armed?
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No, the scolex does not contain any hooks.
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How are cattle infected with T. saginata?
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By ingesting eggs on pasture or through a contaminated environment.
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Direct transmission of T. saginata.
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Eggs reach pasture by direct deposition of human feces
RARE in developed nations |
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Indirect transmission of T. saginata
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sewage, sludge on agricultural land
Birds: serve as a transport mechanism for whole proglottids |
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Epidemiology of T. saginata
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May be found in any straited muscle but highest in density are heart, tongue, and masseters
Cuts are made in these during meat inspection |
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Enzootic instability
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Good sanitation, very low prevalence in human population low transmission rates to cattle low prevalence in cattle sporadic ‘storms’ of infection
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Enzootic stability
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High prevalence in humans due to lack of sanitation high rate of transmission to cattle many calves infected calves infected, but animal immune to reinfection
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Is T. solium armed?
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Yes, it has hooks on its scolex.
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Life cycle of T. solium
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Similar to T. saginata except pig is the intermediate host.
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What part of the body of pigs and humans does T. solium infect?
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The brain and musculature.
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General characteristics of Taenia spp. in dogs.
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Adults live in small intestine and appear to cause little harm, although exiting proglottids may cause pruritis
Main issue is in intermediat hosts: ie sheep PPP 6-8 weeks Taenia segments ≠ Dipylidium!!! Are rectangular Only one lateral genital pore Eggs are single, not in packets like dipylidium |
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Life cycle of T. hydatigena
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Oncospheres hepatic portal system transform to cysticerci grow rapidly while migrating through liver parenchyma PERITONEAL cavity
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How does T. hydatigena hurt/damage sheep?
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Damages liver, and liver heals forming fibrous tracts condemnation at meat inspection
Can cause massive liver damage and death |
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Life cycle of T. multiceps (aka Multiceps multiceps)
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Eggs hatch in SI of sheep
Onchosphere blood circulation brain migrates through brain tissue coernus inside skull lying on surface of brain |
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Neurological signs of T. multiceps in sheep?
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ataxia, circling, blindness
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General info on T. ovis
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Similar cycle to T. hydatigena
Cysticerci occur in MUSCULATURE Condemnation of meat on aesthetic grounds |
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General info on T. pisiformis
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Similar to T. hydatigena, except cysticerci are pea sized and found on omentum of rabbits
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General info on T. serialis
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Coernus forms in intermuscular connective tissue of rabbits
Pet rabbit probably get it from wild foxes |
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General info on T. taeniaeformis
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CAT Taenia
Pea sized nodule metacestode found in liver of mice and other small rodents Cats can continue to be reinfected (hunters) |
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General characteristics of Dipylidium caninum
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Very common in cats and dogs.
Minor clinical sign: anal irritation. Recognition: Segments are oval in shape Two lateral genital pores Clusters of eggs in packets |
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Dipylidium caninum lifecycle
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When ingested by flea larvae onchosphere transforms to a cysticercoid which is infectie flea is swallowed during grooming
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General info on Anoplocephala spp.
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Intermediate host are free-living pasture mites
Mestacestode is a cysticercoid Horses become infected when grazing |
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General info on Moniezia spp.
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Intermediate host are pasture mites
Sheep and cattle (mostly lambs) |
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General info on Davainea spp
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Poultry tapeworm
Intermediate host are: earthworms, beetle, mollusk, insect, etc |
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General info on Spirometra spp.
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Pseudophyllidean
Several spp Dogs and cats are final hosts Aquatic copepods are the first intermediate host, and vertebrates such as frogs, snakes, rodents are second intermediate hosts Humans can be infected Sparganosis |
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What is the treatment for tapeworms?
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Praziquantel
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