parasitic diseases of GI tract (5) Flashcards
what are the most common protozoa infections in the US (2)
giardia lamblia
cryptosporidium parvum
what are the 2 morphological forms of giardia?
cysts (infectious
trophozoites
it can be difficult to recognize a water supply with infected giardiasis while it goes on affecting a whole community, why is this?
because the asymptomatic infection occurs in 50% of people, and in 5-15% of people there is shedding of the cysts
how do you diagnose a giardia infection
initially stool microscopy and then immunoassays for greater sensitivity
how is cryptosporidium transmitted
oocysts in the feces to person, food or water
besides GI effects, what other system can be involved in cryptosporidium
biliary tract infection
what causes intestinal amebiasis
protozoan Entamoeba histolytica
what some extraintestinal manifestations of entamoeba histolytcia
amebic liver abscesses
more rare: pulmonary, cardiac and brain involvment
in most infections with e. histolytica, the trophozoites in the intestines just aggregate in the intestinal mucin layer, form new cysts and cause a self limited/asymptomatic infection..what is the other possibility of what could happen? explain how this happens
adherence to and lysis of the colonic epithelium, mediated by the galactose and N acetyl D galactosamine specific lectin which initiates the invasion of the colon by the trophozoites
what is the most common disease manifestation of infection with E. histolytica
amebic diarrhea without dysentery
what is amebic dysentery (aka amebic colitis)?
diarrhea with mucus or visible or microscopic blood
a patient just came back from traveling and has right upper quad pain and fever, what are you thinking about
amebic liver abscess from a E. histolytica infection
common name for taenia solium
pork tape worm
think, solium looks like sodium and ham is known for being salty
common name for taenia saginata
beef tapeworm
common name for dihyllobothrium latum
fish tapeworm
what is the rule about humans being a host a cestode parasite
humans are either definitive or intermediate host but not both
1 exception- T. solium
what tapeworms are humans the definitive host
D latum and T. saginata
if a human ingests an egg in food or water contaminated with T. solium what develops?
cysticercus (esp in the brain)
how does T. saginata infect humans? what disease does it cause
larvae in undercooked beef
causes adult tapeworm
how does D. latum infect humans? what disease does it cause
larvae in undercooked fish
adult tapeworm
which tapeworm can cause B12 deficiency
D. latum
how does echinococcus granulosus infect humans? what disease does it cause?
eggs in food or water contaminated with DOG feces
causes hydatid cysts, esp in liver and lungs
which of the tapeworms is a major cause of adult onset seizures
T. solium cysticercosis
so your patient just ingested an undercooked piece of pork that you suspect has T. solium infection, so now you should look out for seizures?
NO. undercooked pork cannot cause cysticercosis.. it results in intestinal tapeworm (which can be asymptomatic) if the pork indeed had larval cysts
what are cestodes? and what helminths are in this group
flat worms
Taenias
D. latum
echinococcus granulosus
what are the 2 main parts that make up a cestode
rounded head- scolex
flat body with multiple segments (each segment is called a proglottid)
so you said D. latum can cause vit B12 deficiency. what are the 2 ways it does this
- parasite mediated dissociation of the vit B12-IF complex in the gut lumen
- the parasite actually uptakes the vitamin and uses it for is SHELLFISH self (get it..selfish, but also shellfish because this is transmitted via undercooked fish)
what are the 6 nematodes (roundworms)
- enterobius- pinworm
- trichuris- whipworm
- ascaris-giant roundworm
- necator- hookworm
- ancylostoma- hookworm
- strongyloides- small roundworm
how do you get an infection with
enterobius (pinworm)
trichuris (whipworm)
ascaris (giant worm)
how is it diagnosed?
ingestion of eggs
dx by eggs on the skin
how do you get an infection with
ancylostoma and necator (hookworm)
strongyloides (small roundworm)
how is it diagnosed?
larval penetration of skin
dx by eggs in stools
where are the adult worms in an ascaris infection
free in lumen of small bowel
mainly jejnum
where are the adult worms in an trichuris infection
anchored in superficial mucosa of cecum and colon
where are the adult worms in an necator and ancylostoma (the hookworms) infection
attached to mucosa of mid to upper portion of small bowel
where are the adult worms in an strongyloides infection
embedded in mucosa of duodenum, jejnum
where are the adult worms in an enterobius (pinworm) infection
free in lumen of cecum, appendix, adjacent colon
whats the most common helminthic infection in humans? in the US?
ascariasis in the world
enterobiasis (pin worm) in the US
ascariasis infection is usually asymptomatic, but if it invades the lung tissue, what can it cause
provokes an immune mediated hypersensitivity response
nonproductive cough, chest discomfort, fever and eosinophilia
severe can develop loffler syndrome
what are the most common symptoms of enterobiasis (pin worm)
perianal itching (at night time the worms migrate to the perianal area and lay their eggs)
what helmith can you see anal prolapse
trichuriasis
what deficiencies can hookworm be assoc with
iron deficiency anemia and protein energy malnutrition
