Lecture 72 - Helminths: Cestodes and Trematodes Flashcards
What are characteristics of trematodes?
what are the trematode of interest?
Trematode -- non segmented flat worm GI tract Hermaphrodites Molluscan interemediate hosts Vertebrate adults hosts
Blood flukes: Schistosoma
Oriental Liver Flukes: Chlonorchris, Opisthocrhis
Describe the lifecycle of schistosoma
Humans excrete eggs through urine or feces
Eggs hatch in water
Miricida - larval stage after hatching
seek out molluscan host
Develop into and released as Fork tail Circaria
Penetrate the human skin
In the dermis – sheds glcolcaylx
Finds way to preferential venous plexus in 48 hours
Full matures in 6 weeks
Finds mating pair — produces 40 K eggs per day
Eggs are immunogenic
high burden can invade billiary tree, kidneys, brain
Mating pairs can live from years to decades
What are the initial symptoms of schistosomiasis?
Penetration of the cercaria into the skin = Swimmers itch
a hypersensitivity rash — mediated by Th1, Eosinophils and IgE
Describe acute Schistosmiasis
what is it also known as ?
Underlying pathology?
Symptoms ?
Katayama Fever
Serum Sickness – We are reacting very aggresrively to the egg
Fever, HA, cough, abdominal pain
Death in severe cases
Chronic Schistosomiasis
what is the underyling pathology?
what are some manifestations if acquired as a child?
Granulomas: Eggs become trapped in tissue Eosinophilic reaction occurs
Granulomas form followed by fibrosis
Childhood Acquisition: Growth Retardation, Anemia, cognitive impairment and memory deficits
Chronic Schistosomiasis: Liver manifestations
what are the bugs
symptoms?
S. mansoni/S. japonicum:
Liver Affinity: Bloody diarrhea, intestinal polyps and strictures
Chronic Schistosomiasis: Urinary Schistosomiasis
the bug?
pathogenesis?
symptoms?
S. heamatobium
Migrates up GU tree;
Manifestation: Hematuria; polyps; bladder calcifications and strictures
Leading cause of bladder cancer world wide
Eggs can go into lungs
Chronic Schistosomiasis:
Neuro-Schistosomiasis
Eggs travel aberrantly to the brain and Spinal cord
Myelitis, mass lesions in the brain
Can cause sudden paralysis
Dx of Schistosomiasis
Identification of eggs in stool or urine (different spines)
Serological Tests
treatment of Schistosomiasis
mechanism:
Advantage:
Disadvantage:
Praziquantel
increases calcium permeability across tegument; exposes worm antigen to host’s immune system
Cheap, taken PO, few side effects
immature schistosomula are immune to treatment
What are the oriental liver flukes?
Lifecycle and
Transmission?
Pathogenesis:
Trematodes
Species:
Chlonorchis, Opisthochris
Lifecycle –
Eggs in water find mollusk
released as fork shaped Cercaria
Cercaria eaten by fish
Transmitted: Undercooked fish
Pathogenesis: burrow in biliary tree; RUQ pain
Cestodes
Characteristics
infectious forms
cestodes of clinical interest
cestode:
Segmented Flatworm
Segments are hermaphrotidic
No GI tract
forms of infection:
tape worm, hydatid cyst, both
of interest: Diphyllobothrium latum (Fish tapeworm)
Taenia
Eichinococcus Granulosum
Diphyllobothrium latum
aka –
aka (Fish tapeworm)
Describe the Life cycle of Diphyllobothrium latum
- whats unique about the egg?
- transmission
- where do they reside in our bodies?
- how big can they get?
1) unembryonated eggs passed in feces
2) embryonated eggs in water
“operculum pops open”
which hatch and find their way to a mollusk or crustaecean host
3) Crustacean is eaten by bigger fish; eventually may be eaten by humans
Acid of our GI allows the cyst to develop into a worm
Acquired from eating raw or undercooked fish
Reside the mucosa of the bowel
can growth up to 30 feet
Symptoms of Diphyllobothrium:
Very mild overall
Vague abd discomfort;
Some muscular weakness
Some anemia and increased heart rate
Treatment of Diphyllobothrium
Praziquantel or niclosamide
Taenia
aka
Pork and Beef tapeworm
Taenia
describe the lifecycle
transmission – 2 types
Humans expell the eggs into the environment
Ingested by pigs, cattle
eggs hatch and penetrate the GI wall, enter the musculature as CYSTICERCI
Transmission:
Mostly ingestion of the meat with cysticerci which can then develop into the worm
occasional ingestion of the egg and we develop cysticerci in our own bodies
what happens if you ingest the tinea encysted meat via pork or beef?
what are the symptoms?
how do you treat?
the cyst evert in our guts and attach the intestinal mucosa
Develop into adults worms (15-20 feets)
Can live for years
Mild symptoms
Treat: Niclosamide or praziquantel
what if you ingest the tinea eggs themselves?
what is a common presentation?
Symptoms
Treatment
Have tendency to invade the CNS — Neurocysticercosis
common presentation: a new onset seizure
Other
Seizures
Hydrocephalus
Treatment:
Reduce inflammation
Praziquantel 1-4 weeks
Surgery to remove the cystocercosis
Eichinococcus Granulosum
what is the exception regarding this parasite’s infectious form compared to other cestodes?
In this case, just the cyst in the infectious form
Eichinococcus Granulosum
describe the lifecycle
who are the definitive, intermediate and dead end hosts ?
where is it commonly found?
Dogs – definitive host
Sheep – intermediate host
humans - dead end host; do not transmit —
commonly found in herding populations
Lifecycle: Egg excreted by dogs Infects sheep, goats Humans eat the sheep/goats which contain the embryonated egg
describe the pathogenesis of
Eichinococcus Granulosum
what tissues are most commonly affected
what happens if a cyst ruptures?
Larva develop into large, fluid filled bladders (hydatid cysts),
contain tons of tiny solices
Each Scolice can develop into its own worm or daughter cysts
Cysts: 75% Liver, 25% lung, 1% bone, CNS
Rupture: anaphylaxis, secondary cysts, biliary obstruction
Treatment of Eichinococcus Granulosum
Surgical Removal of Cyst – PAIR technique
Follow up - high does long term ALBENDAZOLE, MEBENDAZOLE
