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What are cestodes?
They are tapeworms which live attached to the mucosa of the small intestine.
*Absorb protein & carbs to reproduce
- Scolex is organ of attachment
- Proglottids is attached to scolex
- Stobila is the chain of proglottids
Diphyllobothrium latum - d. latum
- Human eats under-cooked fish
- scolex, proglottis, & adults harbor in small intestine.
- human passes unembronated egg
- embryonated eggs infect crustacean which
- then infect fish.
Who is the definitive host & intermediate host
Definitive:humans, dogs, foxes, cats, seals, etc. that might eat fish
Intermediate: copepod(crustacean), fish, pike or salmon are common
Location & Disease
Europe, Russia,Israel,US in heavy fish eating regions. ie. Great Lakes Region
sparganosis (larval infection), anemia (B12), obstruction, diarrhea, abd pain
Eggs or proglottids in stool
Cestode: Taenia species -
Life Cycle - same for saginata and solium
- 1) Animal (Beef/Pork) eat infected vegetation
- 2) Oncospheres hatch & invade intestinal wall then migrated to striated muscles.
- 3) Develop into cysticerci.
- 4) Humans eat undercooked meat.
- In 2 mos time, cysticerus mature to adult tapeworm.
- 5) Adults attache to small intestine & produce proglottids.
- 6) Proglottids leave via stool with eggs.
*In Solium: if eggs ingested, oncosphere hatch and move to muscle of man instead of pig.
T. saginata - Beef Tapeworm
Worldwide - rare in US
Few symptoms: discomfort, proglottids crawling out of anus
- Scolex: 4 Suckers, NO hooks
- Proglottids: 15-20 lateral uterine branches
Egg: 35-45um with Radial striations
T. solium - Pork Tapeworm
Worldwide - rare in US
Disease: Taeniasis or cysticercosis
cysticercosis must be surgically removed
What is the intermediate host
Cow - beef
What is intermediate host
Pig - pork
- Scolex: 4 Suckers with a central crown of HOOKS.
- Proglottids: 7-13 uterine branches (usually 9)
Egg: Identical to T. saginata
T. saginata & T. solium
Eggs are identical - treatment same for both.
- Count uterine branches
- Solium has hooks too.
Cestode: Hymenolepis nana - H. nana
is also known as:
Location / clinical disease
- Worldwide - common in children
- Spread person to person via eggs
- Autoinfection possible
- hymenolepis - can by asymptomatic, symptoms may include headache dizziness, abd pain, diarrhea.
Worm & Egg Identification
- Worm: up to 40mm long
- Scolex: 4 small suckers & short rostellum with hooks.
Egg - Round to oval, thin wall 30-45um
Recovery of characteristic eggs in stool.
Adult rarely found
Hymenolepis diminuta: H. diminuta:
Diagnosis & Worm & Egg Ident
Recovery of eggs. adult rarely found
Worm: adult 20-60cm long
- Eggs are similar to those of H. nana
- *little more round thought* (my thoughts.)
Diipylidium caninum - Dog Tapeworm
Location / disease / life cycle
- Dogs & cats are host.
- Humans (usually young children) accidental host via eating fleas.
indigestion, abd discomfort, eosinophilia
Recovery of egg packets or proglottids.
- O&P may not be useful if proglottids are not seen.
- *Gravid segments are small, white, & motile & sometimes mistaken for pinworms.
Echinococcus granulosis : E. granulosis
- Adult worm in dogs intesting
- Proglottids & eggs passed
- Eggs ingested by intermediate host (man)
- Hatch in duodenum, oncospheres penetrate intestine & moves into bloodstream
- Various organs affected.
- cysts contain protoscolices or hydatid sand
- Echinococcosis,, hydatid cyst disease -
- Cyst location determines severity
- Liver 65%
- lungs 20%
- brain 1% or kidney 3% or peritoneal 7%
Treatment & Diagnosis
Dx. Abd mass, EITB, pathology (examination of cyst fluid)
Treatment: Surgery, removal of cysts.
If rupture, anaphylactic reactions may occur!