Cestodes Flashcards

Question

Dipylidium caninum life cycle

Answer 1

Adults in SI of dog/cat/man 50cm--\> 3 weeks post infection, gravid segments shed--\>eggs ingested by flea/louse IMH Cysticercoid in haemocoel (body space of flea/louse) cysticercoid=tiny solid cyst with single head Ingestion of flea/louse by dog/cat--\> head latches in SI Adult worms have different shaped segments Has rostellum with hooks and suckers

Answer 2

Fleas: larvae, not adults, adult mouthparts can't ingest eggs important IMH (flea larvae): Ctenocephalides canis, Ctenocephalides felis, Pulex irritans Lice: all stages--Tricodectes canis

Answer 3

active motile segments, elongate shape (rice grain) DOUBLE GENITAL PORE: little holes in sides of tegument where eggs can be released from EGG PACKETS: can tease segment apart in saline and egg packet will pop up nb: don't usually see eggs in feces because they're enclosed double genital pore and egg packets are diagnostic features

Answer 4

Double genital pore in dipylidium and presence of egg packets also, in d. caninum, segments looks like rice grains and have motile segments Why do we need to distinguish? Control Taenia= praziquantel Dipylidium: praziquantel + flea/lice tx

Answer 5

Final host: dog, wild canids Site: SI IMH: ruminants, pig, man Zoonotic

Answer 6

final host: dog, red fox Site: SI IMH: horse/donnkey not zoonotic

Answer 7

small ~6mm scolex plus 3-4 segments in SI of dog gravid segment is usually about 1/2 length of the whole worm. Eggs similar to taenia: 6 hooks, radially striated, passed in dog feces.

Answer 8

Adults in SI of dog (Final host)--\> gravid semgents shed 1 per week--\> egg resistant (thick, striated egg shell) Egg ingested by IMH--\> onchosphere released and penetrates SI well--\> hydatid cyst in IMH liver/lungs 6+ months post infection Hydatid cysts can form anywhere in the body but usually found in liver/lungs. Hydatid cysts have protoscoleces. Cysts ingested by final host--\> adults in SI Tiny worm takes ~7 days for next segment to become gravid, however SI likely has thousands of worms in an infected dog. PPP= 40-50 days from ingestion of cyst to eggs shed in feces.

Answer 9

Pathology is associated with cystic stage not the adult worm

Answer 10

Horses and cattle (cattle not natural IMH): 90% of hydatids in liver Sheep: 70% in lung, 25% in liver most cysts in cattle are sterile- don't have all heads of future tapeworms in hydatid

Answer 11

Cyst wall: thick Germinal epithelium: cells similar to stem cells Protoscoleces bud off from germinal epithelium- this process just carries on happening. Liver/lung constrains cyst size, but if cyst is in peritoneal vaity, cyst can get quite big. Hydatid sand: protoscoleces or heads of future tapeworm. This is what you would see if you took an aspirate from it.

Answer 12

IMH: abattoir Final host: fecal egg count; copro-antigen test (picks up antigen released by parasite); copro-PCR (picks up DNA released by parasite) In sheep, see clincal signs if cyst is in a weird place i.e. brain/pancreas

Answer 13

Mostly well tolerated in IMH unless cyst is in an unusual site Most cases detected in abattoir not pathogenic in dog final host always of significance in humans

Answer 14

E. granulosus sylvatic cycle: host- wild dog, IMH- ruminant- maintained by predation/carrion feeding E. granulosus domestic cycle: host-dog, primary IMH- sheep (hydatid more infective from sheep)-- Man becomes infected from dog (i.e. man is IMH instead of sheep) E. equinus (not v. common in UK, but rather from european imports): host-dog/red fox-- equine abattoirs/hunting kennels--maintained by feeding hunting dogs on equine viscera.

Answer 15

IMH depends on local animal husbandry in UK, sheep is most important, but elsewhere can be camels or reindeer.

Answer 16

Man is accidental IMH Most common in sheep farming areas Requires close man-dog contact Man becomes infected via ingestion of onchospheres from water, foodstuffs or coat of dog

Answer 17

break cycle by: regular deworming of dogs with praziquantel, proper disposal of infected carcasses, deny access of dogs to abattoirs, hygiene to control human infection.

Answer 18

introduced with sheep spread from domestic animals into dingoes as final host and wild marsupials as IMH- sylvatic cycle established cycle re-introduced to domestic dogs in some areas by hunters allowing dogs to feed on offal from wildlife. Control: praziquantel, dried dog food too, better diagnosis (ELISA to detect copro-Ag), education

Answer 19

final host: dog, cat, wild canids IMH: lemings, voles, man Life cycle similar to E.g. granulosus Important zoonosis Prevalent in europe

Answer 20

similar to granulosus Adults in SI (fox)--\> gravid segments shed in feces--\> eggs resistant to -50C--\> ingested by rodent IMH--\> embryo released, penetrates SI wall--\> usually goes to liver via hepatic portal vein where embryo rapidly vesiculates (sits in liver and forms big vesicles). IMH usually gets sick, can't run as fast rodent+cyst ingested by fox

Answer 21

Dogs and cat must be treated against E. multilocularis 24-48 hours prior to returning to UK (praziquantel) Human cases: 15% prevalence in parts of china and tibet urban foxes in zurich and stuttgart infected, prevalence rates 20-47% no +ve foxes in recent UK survey

Answer 22

Causes alveolar echinococcosis potentially fatal if untreated, long asymptomatic periods (5-15 years) followed by clinical signs tx: liver transplant, section or albendazole Alb+ surgery improves 10 year survival rates from 6-25% to 80-83%

Answer 23

Anoplocephala perfoliata\*\* Anoplocephala magna Paranolocephala mamillana Site: small and large intestine IMH: orbatid forage mites

Answer 24

prevaelence 14-81% High prevalence at temperate climates Ulcerations at site of attachment of parasites--\> risk factor for ileo-caecal colic. A. perfoliata have suckers and lappets just underneath sucker. not sure what lappets do, but maybe they're sensory organelles? either way, very characteristic for A. perfoliata Segements are MUCH wider than long.

Answer 25

Adults at ileo/caecal junction--\> eggs pased in feces--\> ingested by forage mite IMH--\> forms cysticercoid in mite Infected mite ingested by horse--\> attaches to gut wall in horse--\> adults at ileo/caecal junction PPP=6-10 weeks

Answer 26

Horses with tapeworms are more likely to suffer colic 80% of 20 cases of ileal impaction colic were tapeworm associated 22% of 95 spasmodic colic cases were tapeworm associated Treat with PZQ +/- ivermectin

Answer 27

FEC: low sensitivty, high specificty Eggs are misshapen- odd-looking- have pyriform appartus. In fresh specimen, looks like a stalked mushroom and embryo sits on top. ELISA and Corp-Ag PCR.