W6- Phylum Platyhelminthes (Class Cestoda) Flashcards
What is class Cestoda known as?
they are Tape worms from phylum Platyhelminthes
Characterics of class cestoda
endoparasites(lives inside tissues of host)
- multisegment, dorsoventrally flattened tape-like worms
- NO digestive system
- hermophrodites (M+F)
Class Cestoda morphology
3 parts: Scolex(head), colon(neck), Strobila(body).
- Scolex: organ of attachment to intestinal mucosa of def host.
- Colon: region of grown, budding of new proglottids.
- Strobila: composed of a chain of proglottids.
> immature proglottids- near neck, repro organs not well developed.
> mature segment- every segment contains both M+F sex organs.
> gravid segment- at hind end, filled by uterus w/ egg. leave host in feces.
What are proglottids?
they are the segments that make up body of tape worms, they contain sexually mature reproductive system.
What is strobilation?
asexual process of forming segments. each segment had testes and ovaries
what is Diphyllobothrium latum known as?
fish or broad tapeworm
what does Diphyllobothrium latum cause
Diphyllobothriasis
may cause vit B12 deficiency + megaloblastic anemia.
Diphyllobothrium latum habitat
in small intestine/ ileum
Diphyllobothrium latum morphology
20m
scolex has 2 bothria (slit like grooves) for attachment to the intestine.
Proglottids are wider than
long.(3000-4000 prog) mature prog has M+F repro organs.
Gravid proglottids= flower like uterus.
ovary is bi-lobed
testes= minute follicles located laterally in dorsal plane.
adults can shed 1 mill eggs a day.
Diphyllobothrium latum host
def host: humans (fish eating mammals)
2 inter hosts:
1) copepod crustaceans
2) freshwater fish
Diphyllobothrium latum life cycle
- unembry. eggs passed in faeces
- Eggs embroynate in water and hatch into Coracirdia they are ingested by copecod crustaceans+and in their body cavity procercoid larva
- procercoid larva ingested by fish and migrate to muscles via bloodstream—>plercercoid larva
- mammals eat infected fish, humans consume undercooked infected fish
- adult worms develop in small intestine is immature eggs are passed in feces
what is Taenia saginata known as?
beef taenia, taeniarhynchus sagiantus
Taenia saginata morphology
5-10m, ribbon-like
scolex: 4 suckers, no rostellum- attachment to organ.
dorsoventrally flattened
gravid proglottid more than 12 uterine branches on each side
Taenia saginata host
def host: humans ONLY inter host: cattle
Taenia saginata habitat
SI, jejunum
Taenia saginata cause
taeniosis
Taenia saginata transmission
eating raw or undercooked meat containing cysticercus bovis.
Taenia saginata infective stage
Cysticercus bovis (larval stages)
Taenia saginata + Taenia solium difference
gravid proglottid:
saginata: more than 12 uterine branches on each side
Solium: less than 12 uterine branches on each side
Scolex:
saginata: 4 suckers
Solium: 4 suckers, rostellum w/ 2 rows of hooks
What is Taenia solium known as?
pork tenia
Taenia solium cause
taeniosis,
cysticerci causes cysticerosis= in brain auto-infection
Taenia solium habitat
SI
Taenia solium morphology
3-4m, dorsoventrally flattened
scolex: 4 round suckers + rostellum w/ 2 rows of hook
neck: narrow, unsegmented
body: segmented, (I,M,G), mature proglottids ovary is 3 lobed.
gravid proglottids= less than 12 uterine branch on each side
Taenia solium host
def host: Humans inter host: pigs
Taenia solium infective form
cysticercus
Taenia solium transmission
Eating raw/undercooked meat containing cysticerci (cyst)
Taenia solium transmission
- Eating raw/undercooked meat containing cysticerci (cyst)
- auto infection- patient already has taeniosis. vomiting=brings gravid proglottids to stomach eggs and oncosphere released
What is oncosphere?
6 hooked larval stage– attach + penetrate intestinal wall
what is Hymenolepis nana known as?
dwarf tape worm, Taenia nana
Hymenolepis nana cause
hymenolepasis
Hymenolepis nana transmission
Ingestion of F/W contaminated with eggs
Internal water infection – egg is released in intestine hatch there
External autoinfection – person ingests own eggs by fecal-oral route
Hymenolepis nana morphology
especially in children
40 mm
> Scolex= 4 suckers and retractile rostellum w/single row of hooklets
> neck= long slender
> uterus= lobulated walls, 3 rounds testes
Hymenolepis nana infective form
embryonate eggs
Hymenolepis nana infective form
embryonated eggs
Hymenolepis nana life cycle
- eggs passed w/ feces
- eggs ingested by Beetles
- Eggs —>cysticercoids. when ingested rodents/ humans=infected
- oncospheres hatch+develop into cysticercoids on intestinal walls. scolex forms, adult resides in ileum, SI.
- gravid proglottids release eggs which is passed in stool. gravid can also disintegrate releasing eggs.
- autoinfetion can occur if eggs remain in intestines. eggs releases embryo which penetrates the Vilius continuing the cycle.
also, embryo. eggs ingested by humans from contaminated f/w=autoinfection
Echinococcus granulosus habitat
jejunum+ duodenum of dogs
why is Echinococcus granulosus most dangerous?
Can be infected by inhalation of parasite.
what is Echinococcus granulosus known as?
dog tapeworm, hydatid tapeworm
Echinococcus granulosus transmission
Ingesting F/W contaminated w/ dog feces, through direct contact with infected dog, can be inhaled
herbivores infected by ingesting eggs
Echinococcus granulosus cause
cystic echinococcosis= hyatid disease
enlarging cysts in organs
Echinococcus granulosus host
def host: dogs inter host: herbivores animals (sheep, cattle)
Echinococcus granulosus morphology
3–5 mm
>Scolex: pear-shaped w/ 4 suckers+ rostellum w/ 2 rows of hooks
>Neck = short
>Strobila = 3 proglottids (I,M,G)
eggs= ovoid, brown , 3 pairs of hooklets
Echinococcus granulosus infective form
eggs
Echinococcus granulosus life cycle
- mbryonated eggs shed with feces
- eggs ingested by herbivore,eggs hatch in SI—> oncosphere(6hooked larva). this penetrates intestinal wall,uses bloodstream to reach lungs and liver.
- in organs, oncosphere developes into hydatid cyst(thick wall)(enlarges)—>protoscolex+ daugher cysts.
- dogs become infected after ingesting cyst.
- after ingestion scolex attatches to intestine.+ develop into adult stages.
