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ABBEY MSII U6 > Micro parasitic infections of GI > Flashcards

Flashcards in Micro parasitic infections of GI Deck (51)
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who does giardiasis infect?

beavers, raccoons
high risk = infants, young children, international adoptees, travelers, immunocompromised, hypochlorhydria or cystic fibrosis


describe the life cycle of giardia

cysts are the infectious form (survive in moist environments for prolonged periods) --> transmitted via water, food, fecal-oral --> ingestion of 10-25 cysts leads to giardiasis --> following ingestion, excystation occurs in proximal small bowel with release of trophozoites


what are the clinical manisfestations of giardia?

50-65% asymptomatic.
35-45% symptomatic with prolonged duration of diarrhea, weight loss 10 pounds, malaise, abdominal cramps/bloating, FLATULENCE, nausea, STEATORRHEA


what is the incubation period of giardiasis?

1-2 weeks


what is giardia?

protozoal parasite (single celled organism)


what are the symptoms of chronic giardiasis?

loos stools (not diarrhea), steatorrhea, profound weight loss, malabsorption, malaise, abdominal cramping, borborygmi, flatulence, burping, fatigue, depression (basically same but wax and waning of symptoms)


diagnosis of giardia

stool examination for ova and parasites looking for trophozoites or cysts
ALSO detection of giardia specific antigen (GSA-65) through ELISA or immunochromatic assays


treatment of giardiasis

tinidazole (like metronidazole)


what is cryptosporidiosis?

an intracellular protozoan parasite that is associated with self-limited diarrhea in immunocompetent hosts, persistent diarrhea in children in developing countries, and chronic diarrhea in immunocompromised


what is cryptosporidiosis associated with?

unfiltered well water


how does transmission of cryptosporidium occur?

fecally passed oocysts (immediately infectious)
although mainly through contact with contaminated water (through run off of manure especially - also swimming pools)


what are cryptosprodium oocytes resistant to?



clinical manifestations of cryptosporidium

incubation 7-10 days - can have asymptomatic, mild diarrhea, or severe enteritis
diarrhea as associated malaise, nausea, anorexia, crampy abdominal pain, low fever


cryptosporidium treatment

usually resolves without therapy in 10-14 days - difficult to treat if becomes chronic


cryptosporidiosis diagnosis

microscopy or enzyme immunoasays - may be present in stool, duodenal aspirates, bile secretions


what does entamoeba histolytica cause?

intestinal amebiasis - usually asymptomatic but can cause amebic dysentery and extraintestinal disease (amebic liver abscess)


what are the forms of entamoeba histolytica

single celled protazoa with two forms: cyst stage (infective) and trophozoite (invasive disease)


entamoeba histolytica ID

one cysts is sufficient to cause disease


clinical manisfestations of entamoeba histolytica. what are they due to?

tissue destruction (abdominal pain) , increased intestinal secretion, bloody diarrhea due to trophozoites invading and penetrating the mucous barrier of the colon


entamoeba histolytica transmission

ingestion of amebic cysts via contaminated food or water also associated with venereal transmission via fecal-oral


treatment of entamoeba histolytica

ALL should be treated (prevent spread) - 10 day course of metronidazole eliminates intraluminal infection - usually need second agent


what are the intestinal cestodes (tapeworms)? which are humans definitive hosts for? intermediate hosts?

taenia solium (pork tapeworm) - exception - usually only definitive of intermediate - this one could be either
taenia saginata (beef tapeworm) - definitive
diphyllobothrium latum (fish tapeworm) - definitive


taenia solium - stage that infects humans and stage most associated with disease

infects: larval cysts in nundercooked pork; eggs in food or water contaminated with human feces
disease: adult tapeworm in intestine; cysticerus especially in brain


taenia saginata - stage that infects humans and stage most associated with disease

infects: larval cysts in undercooked beef (usual intermediate host)
disease: adult tapeworm in intestine


diphyllobothrium latum - stage that infects humans and stage most associated with disease

infects: larvae in undercooked fish
disease: adult tapeworm in intestine can cause vit B12 deficiency


what is cysticercosis? which parasite is it associated with?

A tapeworm infection that affects the brain (seizures), muscle, and other tissues (when serving as an intermediate host) - associated with taenia solium


what are areas of t. solium infection?

mexico, c america, s america, africa, se asia, india, philippines, s europe


clinical presentation t solium

generally asymptomatic unless cysticercosis caused by autoinfection with parasite eggs supervenes


how is t solium infection diagnosed?

detecting eggs during stool examination


t solium cysticerci transmission

fecal oral - eggs shed in stool of a human tapeworm carrier