Trematodes and cestodes Flashcards
Trematodes are (segmented/non segmented) parasites flukes with a GI tract, ___ intermediate host and ___ adult host
Trematodes are non segmented parasites flukes with a GI tract, mollusk intermediate host and vertebrate adult host
Briefly describe the lifecycle of Schistosomiasis
Lifecycle:
Eggs released in water >> hatch as miracidia and live in snails >> asexual replication within the mollusk host >> released as miracidia into the water >> develop into cercariae are free swimming and get into human host >> bug migrates to a preferred venous plexus
Which spp of Schistosoma likes the venous plexus close to the bladder?
S japonicum and S mansoni like the ___ plexus
S haematobium likes the venous plexus close to the bladder
S japonicum and S mansoni like the inferior venous plexus in the gut
The __ is the intermdeiate host for the circaria
snail
What type of immune response is mounted against schistosome infection (especially against the circaria)?
Th1 response, eosinophils and IgE to schistosomula
**might also get mild maculopapular rash at site of cercarial penetration**
What happens to the circaria once they make it into the human host?
Once they enter the circulatory system, the cercaria shed their glycocalyx, develop a primitive gut and migrate first thru the lungs, thru the heart and to the liver to a preferred plexus (here it’s the inferior mesenteric plexus)
Will then look for a mating pair and home to their plexus
___ is the result of a strong antigen – antibody response (aka serum sickness) that develops when the worms produce eggs
Katayama fever
Chronic schistosomiasis is also the result of an immunologic response to eggs. Explain how this happens
Chronic schistosomiasis results from aberrant egg migration (to organs such as the liver or the bladder)
Chronic schistomiasis is characterized by the formation of a __ after an intense eosinophilic rxn to eggs in the tissues
This disease can manifest as ___
Over time, the eggs become trapped in tissue and cause a very intense eosinophilic rxn >> granuloma followed by fibrosis
Can manifest as bloody diarrhea, intestinal polyps and strictures
Which stage of schistosomiasis is characterized by the pathology below?
Chronic schistosomiasis
___ is primarily characterized by hematuria
Eggs can also go to the nervous system and cause ___
Urinary schistosomiasis is primarily characterized by hematuria
Eggs can also go to the nervous system and cause transverse myelitis
Some urinary system abnormalities caused by Schistosomiasis include ureteritis, ___ (happens in the kidneys), ___ (can become adenocarcinoma) and squamous cell bladder cancer
Some urinary system abnormalities caused by Schistosomiasis include ureteritis, pyelonephritis (happens in the kidneys), cystitis cystica (can become adenocarcinoma) and squamous cell bladder cancer
How do you Dx schistosomiasis?
Dx: look for eggs within the stool or urine; serologic testing (doesn’t tell active infection. Only tells exposure)
What is the Rx for schistosomiasis?
Rx: praziquantel (but the cercaria are immune so treat initially then follow up a few months later)
Drug works by paralyzing the worm then its excreted out
What is the mechanism of drug resistance in schistosomiasis?
MOR: ATP binding cassettes that pump out the drug from the parasite cells