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
2 most clinically significant liver flukes are __ and __
Clonorchis and opisthorcis
Liver flukes are an important etiological cause of ___
These flukes burrow thru the liver and cause inflammation and pain
Important etiological cause of cholangiocarcinoma
Infection by Diphyllobothrium latum (aka the fish tapeworm) can be acquired by ___
Ingestion of poorly cooked or raw fish.
Infection with these is mostly asymptomatic
**note that they live in the small bowel**
Describe the lifecycle of the fish tapeworm
Unembryonated eggs are released in the feces >> embryonate in the water (eggs have a cap that pops open) >> mature into coracidia >> invade fish >> fish eaten by human host (the mature bug/scoles everts once it his the small intestine
Presentation of infection by fishworms
non specific abdominal discomfort, some patients develop Vitamin B12 deficiency >> Megaloblastic anemia
Dx of fish tapeworm infection
Rx of fish tapeworm infection
Dx: proglottdids/eggs in stool
Rx: praziquantel (#Prazi the Prezident who treats all trematode and cestode infections) or niclosamide
How does one get sparganosis?
Sparganosis: occurs upon ingestion of molluscan intermediate host; eosinophilic and itchy infection
What symptoms of fish infection will you see with chlonorchiasis? (liver flukes)?
Affected systems: eyes/skin; liver; GI
**see diagram below**
Symptoms of diphyllobothrium infection
Affected systems: CNS; skin; cardiac; muscular; GI
Life cycle of taenia solium and saginata (pork and beef tapeworm)
Eggs/proglottids on moist grass taken up by grazing animals >> oncospheres hatch inside intestine and migrate to muscles/other organs >> growth into cystercerci >> human host eats undercooked pork or beef OR human ingestion of oncospheres >> development of cysticercosis
Presentation and Rx of beef and pork tapeworm infection
Non specific symptoms
Rx: Praziquantel or Niclosamide
Presentation of cysticercosis
Generally asymptomatic but can present with seizures, hydrocephalus and brain damage >> death
**causes adult-onset Epilepsy**
Rx for cysticercosis
Mainly reduction in inflammation; surgery if abscesses are big
Drugs: albendazole/praziquantel
The main presenting feature of echinococcus (also a type of cestode) is ___
Liver_cysts
**know that this is ass’d with pastoral transmission so expect someone who’s been rearing cattle and sheep**
Dx of echinococcus infection
CT scan, ultrasound, serologic testing (CDC), aspirate
How dou treat echinococcus liver cysts?
Inactivate cyst with hypertonic saline or toxic solution and surgically remove
PAIR technique: Percutaneous aspiration, injection, respiration
Albendazole/mebendazole: High dose, long-term therapy post surgery
51 year old Guatemalan male who presents with one episode of tonic-clonic seizure activity. Arrived in the United States 2 years prior. Currently employed at McDonalds. He has a heavy history of tobacco use. Reports that he was a pig farmer while in Guatemala.
PMHx: Tobacco use
Symptoms: Normal physical exam without focal neurologic deficit
Laboratories: Normal laboratories. WBC = 10,000 Eosinophils= 8%
MRI- T1 and T2 weighted image
- 2 cm lesion: Left inferior frontal gyrus
- 0 cm lesion: Left superior and middle frontal lobes with ring enhancement
Tx: Surgical removal of large lesion, dexamethasone, dilantin x 6 months, albendazole bid x 10 days.
Imaging is shown below. What is the Dx?
Neurocysticercosis
