Flashcards in Micro parasitic infections of GI Deck (51):
1
who does giardiasis infect?
beavers, raccoons
high risk = infants, young children, international adoptees, travelers, immunocompromised, hypochlorhydria or cystic fibrosis
2
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
3
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
4
what is the incubation period of giardiasis?
1-2 weeks
5
what is giardia?
protozoal parasite (single celled organism)
6
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)
7
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
8
treatment of giardiasis
tinidazole (like metronidazole)
9
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
10
what is cryptosporidiosis associated with?
unfiltered well water
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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)
12
what are cryptosprodium oocytes resistant to?
chlorine
13
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
14
cryptosporidium treatment
usually resolves without therapy in 10-14 days - difficult to treat if becomes chronic
15
cryptosporidiosis diagnosis
microscopy or enzyme immunoasays - may be present in stool, duodenal aspirates, bile secretions
16
what does entamoeba histolytica cause?
intestinal amebiasis - usually asymptomatic but can cause amebic dysentery and extraintestinal disease (amebic liver abscess)
17
what are the forms of entamoeba histolytica
single celled protazoa with two forms: cyst stage (infective) and trophozoite (invasive disease)
18
entamoeba histolytica ID
one cysts is sufficient to cause disease
19
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
20
entamoeba histolytica transmission
ingestion of amebic cysts via contaminated food or water also associated with venereal transmission via fecal-oral
21
treatment of entamoeba histolytica
ALL should be treated (prevent spread) - 10 day course of metronidazole eliminates intraluminal infection - usually need second agent
22
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
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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
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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
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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
26
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
27
what are areas of t. solium infection?
mexico, c america, s america, africa, se asia, india, philippines, s europe
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clinical presentation t solium
generally asymptomatic unless cysticercosis caused by autoinfection with parasite eggs supervenes
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how is t solium infection diagnosed?
detecting eggs during stool examination
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t solium cysticerci transmission
fecal oral - eggs shed in stool of a human tapeworm carrier
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clinical features of taenia saginata
LARGE tapeworms that cause mild abdominal cramps or malaise - can sometimes migrate out of anus and be motile in poo or on clothing
32
diphyllobothrium latum clinical manistestations
normally asymptomatic - some feel weakness, dizziness, salt craving, diarrhea. since the worm can live 30+ years, some develop macrocytic anemia after 3-4 years
33
what are the GI nematodes (roundworms)
enterobius (pinworm)
trichuris (whipworm)
ascaris (giant roundworm)
necator and ancylostoma (two hookworms)
strongyloides (small roundworm)
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what are the MC human parasites?
nematodes
35
ascaris lumbircoides: transmission; person to person?; geographic distribution; duration of infection; location of adult worm
transmission: ingestion of infective eggs
person to person?: NO
geographic distribution: warm, humid ares and temperate zones in warmer months
duration of infection: 1-2 yrs
location of adult worm: free in lumen of small bowl esp jejunum
36
trichuris trichiura (whipworm): transmission; person to person?; geographic distribution; duration of infection; location of adult worm
transmission: ingestion of infective eggs
person to person?: NO
geographic distribution: warm, humid areas and temperate zones in warmer months
duration of infection: 1-3 yrs
location of adult worm: anchored in superficial mucosa of cecum and colon
37
necator americanus, ancylostoma duodenale (hookworms): transmission; person to person?; geographic distribution; duration of infection; location of adult worm
transmission: penetration of skin by flariform larvae
person to person?: NO
geographic distribution: warm, humid areas and temperate zones in warmer months
duration of infection: 3-5 yrs (necator) and 1 yr (ancylostoma)
location of adult worm: attached to mucosa of mid to upper portion of small bowel
38
strongyloides stercoralis: transmission; person to person?; geographic distribution; duration of infection; location of adult worm
transmission: penetration of skin or bowel mucosa by flariform larvae
person to person?: YES
geographic distribution: primary warm humid areas, can be worldwide
duration of infection: lifetime of host
location of adult worm: embedded in mucosa of duodenum, jejunum
39
enterobius vermicularis (pinworm) transmission; person to person?; geographic distribution; duration of infection; location of adult worm
transmission: ingestion of infective eggs
person to person?: YES
geographic distribution: worldwide
duration of infection: 1 month
location of adult worm: free in lumen of cecum, appendix, adjacent colon
40
what is the MC helminthic infection of humans (1/4 world population)? what does it look like?
ascariasis - a white or pinish adult worm that lives and mates in the lumen of the small intestine - primarily jejunum
41
ascaris lumbricoides clinical syndrome
most asymptomatic - small proportion get pulmonary symptoms during second week after ingestion when larvae invade lung tissue and provoke and immune-mediated hypersensitivity response with nonproductive cough, chest discomfort, fever, eosinophilia (disappear when worm reaches maturity)
42
ascaris lumbricoides complications
intestinal obstruction, obstruction of bile and pancreatic ducts, appendicitis, intestinal perforation
43
ascaris lifecycle
live in lumen of small bowel - female produces egs which are passed with feces - unfertifilized eggs may be ingested by not infective. infective eggs swallowed, invade intestinal mucosa when hatched then carried via circulation to lungs - penetrate alvelors walls and ascend bronchial tree, swallowed in throat - develop into adult worms in small intestine
44
enterobiasis vermicularis (pinworm) lifecycle
small white worm (1cm) inhbaiting cecum, appendix, adjacent gut - female worms migrate at night to the perianal and perineal regions where they deposit eggs and die
MC mode transmission via hands of patients through scratching or handling clothes/bed linen
45
enterobiasis vermicularis clinical
symptoms d/t perianal and perineal pruritus and scratching
46
enterobiasis vermicularis diagnosis
paddle test and microscopic exam
47
hookworm (ancylostoma duodenale and necator americanus) clinical syndrome
iron-deficiency anemia and protein energy malnutrition resulting from bloodloss
48
hookworm infection
immature larvae penetrated skin (feet) and then migrate to lung - coughed up and swallowed
49
strongyloidiasis places found
SE US, europe, australia, japan
50
strongyloidiasis clinical syndromes
fluctuating eosinophilia or asymptomatic
some develop maculopapular or urticarial rashes that involve butt, perineum, thighs
51