Flashcards in Micro parasitic infections of GI Deck (51)
who does giardiasis infect?
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?
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?
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
usually resolves without therapy in 10-14 days - difficult to treat if becomes chronic
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