Helminths - Trematodes and Cestodes Flashcards
differentiate trematodes and cestodes
flatworms
- trematodes are non-segmented flatworms/flukes; have 2 sexes
- cestodes are flatworms w/segments; each individual section has both sexual organs; hermaphrodites
life cycle of schistosomes
cercariae are found in water humans swim in
penetrate skin, lose tail, migrate to portal circulation
adults form in liver, then move to either intestinal, GU veins to lay eggs
eggs leave in feces or urine and hatch inf reshwater as miracidia
miracidia infect snails where they develop back into cercariae
where do schistosome infections occur?
contaminated fresh water; eggs released into fresh water will hatch into the infectious cercariae
where do schistosoma mansoni, japonicum, haematobium migrate to lay eggs respectively?
s. mansoni and s. japonicum migrate to mesenteric venules
s. haematobium go to bladder veins
desribe the shape of eggs from the schistosoma spp.
s. mansoni
s. haematobium
s. japonicum
what actually casues the damage in schistosomiasis?
what are the clinical manifestations of each spp.?
eggs are what cause the immune response/damage
acute: fever, HA, coug, ab pain, eosinophilia, prostration
chronic: eggs trapped in tissue; eosinophilic reaction; granulomas develop; fibrosis
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s. mansoni, japonicum: bloody diarrhea, intestinal polyps, anemia
- physical/mental growth retardation in childhood
- s. haematobium: hematuria, bladder calcifications
- neural schistosomiasis: abberent eggs can go to brain and cause inflammation
treatment of schistosomiasis
praziquantel
freezes worms exposing antigens; increases Ca2+ permeability across worm
how do liver flukes cause disease?
where are infections acquired?
reside in biliary tree; burrow through liver; RUQ pain
can also cause cholioangiocarcinoma
you get these from undercooked fish; predominate in SE asia
diphyllobothrium latum life cycle/vector
fish tapeworm!
humans eat contaminated fish w/larvae in their muscles
larvae(plerocercoids) migrate/attach to intestinal wall where adults develop
adults make eggs which pass in stool; if eggs make it to freshwater, cycle starts over
symptoms w/fish tapeworm(diphyllobothrium latum)
diagnosis?
treatment?
non-specific abdominal pain; usually asymptomatic
can have a vit b12 deficiency
eggs found in stool to diagnose
treat with niclosamide or praziquantel
life cycle/vectors of *taenia solium/saginata *
t. solium/saginata are pork/beef tapeworms
- Embryonated eggs and/or gravid proglottids are eaten by pigs/cattle
- Embro hatch in gut and head to muscle via circulation/lymph
- Develops into a cysticercus in the muscle
- Humans eat undercooked meat and ingest **cysticerci **which pop their inverted head out and attach to intestinal mucosa; mature in 2 months
- Humans can also directly inoculate themselves with eggs and get cysticercosis just like the pigs/cattle! –> muscle brain problems
differentiate taeniasis vs cysticercosis infections
Pork/beef tapeworms - t. solium and saginata
taeniasis is where humans ingest contaminated meat containing larvae
- adult worms develop in intestines causing little damage
cysticercosis is where humans directly ingest eggs and their muscles/brain get infected
- seizures, hydrocephalus, brain dmg(neurocysticercosis), death
- leading cause of adult epilepsy(8-10% of ER seizures in LA and houston)
- seen in immigrant population(pig farmers, poverty, poor sanitation)
treatment for pork/beef tapeworms(taenia)
niclosamide or praziquantel
for neurocysticercosis: use albendazole/praziquantel for 1-4wks
echinoccus granulosum causes what type of disease?
manifestation?
hyatid cysts
large fluid filled bladders develop over years which contain millions of scolices
cysts develop most commonly in liver, lung; more rarely bones/cns
rupture causes a severe anaphylactic reaction
transmitted via dog/sheep rearing areas;
how to treat hyatid cysts?
inactivate cyst w/hypertonic saline then remove surgically
albendazole/mebendazole in high doses; long term therapy
