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MICROM 460 > Parasitology Lecture 9 > Flashcards

Parasitology Lecture 9 Flashcards

1
Q

coccidia are _____ ________ parasites

A

obligate intracellular

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2
Q

the ________ (infectious form) have a similar mechanism of cell attachment & penetration

A

sporozoites

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3
Q

coccidia are major pathogens in people who have ______

A

HIV/AIDS

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4
Q

which intestinal coccidia is known to be the most notorious & why?

A

cryptosporidium because its oocysts are immediately infectious

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5
Q

true or false: the oocytes of cyclospora and cystoisospora are not immediately infectious

A

true

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6
Q

cryptosporidium _____/_____ cause gastroenteritis with _______

A

parvum/hominis

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7
Q

________ is the most commonly isolated organism in people who have _____ and are infected with ____

A

crypto, diarrhea, HIV

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8
Q

crypto typically causes ____ and ____ term infection - but it can be serious in ____ or ______ people

A

acute, short, kids, immunocompromised

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9
Q

crypto is shed as ______

A

oocysts

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10
Q

true or false: the oocysts of cryptosporidium are not resistant to chlorination

A

false - they are very resistant (use iodination or boiling)

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11
Q

what encourages the sporozoites to pop out of the oocysts?

A

a drop in pH

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12
Q

the oocyst contains baby _________

A

sporozoites

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13
Q

the progeny of the zygote is the _____

A

oocyst

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14
Q

______ orient their _____ end toward ____ epithelial cells where they invade, but just hang around near the membrane

A

sporozoites, apical, GI

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15
Q

what are the clinical symptoms that crypto causes?

A
  • mild to profuse watery diarrhea

- cramps, nausea, vomiting, weight loss, etc.

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16
Q

true or false: crypto is usually self-limiting but can go longer than 30 days if the individual is HIV+

A

true

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17
Q

true or false: recrudescence with crypto is very uncommon

A

false - it is common

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18
Q

the ______ and ______ are common places for crypto to reside in, but there can be widespread disease in patients with _____

A

jejunum, ileum

HIV/AIDS

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19
Q

true or false: outbreaks of crypto have been found in hospitals, institutions, and day care centers

A

true

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20
Q

typically, children who are infected with crypto are ________

A

asymptomatic

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21
Q

transmission of crypto between humans is through the _______ route

A

fecal-oral

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22
Q

c. hominis is found in _____ only, however, c. parvum is found in ____, _____, _____ and can infect mice & calves

A

humans

sheep, cows, humans

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23
Q

traditional stains (Giemsa) do not differentiate between _____ and similarly sized _____ or other debris

A

oocysts, yeasts

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24
Q

what stain should be used to look for cryptosporidium?

A

modified acid fast stain

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25
Q

what is the size of crypto?

A

4.2-5.4 microns in diameter

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26
Q

an ______ stain can also be used to identify crypto, but you do need a special microscope

A

auramine

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27
Q

an _________ assay can also be used to identify crypto, where antibodies are fluorescently tagged against crypto

A

immunofluorescence

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28
Q

true or false: multiplex PCR has replaced ELISA

A

true

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29
Q

true or false - the infectious dose is very low for crypto

A

true

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30
Q

how can crypto be prevented?

A
  • treatment of water facilities
  • animal waste management
  • boil water (or iodinate, but do not chlorinate - it will not kill crypto!)
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31
Q

what is the treatment for crypto?

A

fluids, electrolytes (for loss of water in profuse watery diarrhea), also Nitazoxanide (antiprotozoal), and ART (if HIV+)

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32
Q

cyclospora cayetanensis causes all ___ cases

A

human

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33
Q

cyclospora is associated with ________ outbreaks or _______ diarrhea

A

foodborne, traveler’s

34
Q

true or false: oocysts from cyclospora are not immediately infectious, they need to progress in the environment for days to weeks

A

true (these are known as unsporulated oocysts)

35
Q

cyclospora typically infects __________ foods like raspberries or basil

A

non-processed

36
Q

cyclospora is often ______

A

asymptomatic

37
Q

the symptoms of cyclospora?

A
  • mild to severe watery diarrhea

- weight loss, abdominal pain, N/V, tiredness, fever, fatigue

38
Q

if untreated, cyclospora can last ____ weeks

A

10-12

39
Q

cyclospora should be treated with _____ if infection persists

A

bactrim

40
Q

true or false: a single negative stool result is enough to diagnose cyclospora

A

false

41
Q

for cyclospora diagnosis, more than __ specimens may be needed at ___ day intervals

A

3, 2-3

42
Q

cyclospora can also be diagnosed via a modified ____ ____ stain or an _____ stain

A

acid fast, auramine

43
Q

similar to cyclospora cayetanensis, cystoisospora ___ only infects humans, and the oocysts are NOT _____ _____

A

belli, immediately infectious

44
Q

from the human coccidian infections, which one is least common?

A

cystoisospora belli

45
Q

symptoms of cystoisospora belli?

A

diarrhea, steatorrhea (fatty stools), headache, fever, nausea, dehydration, water loss,

46
Q

similar to cyclospora, cysto can be treated with ______

A

bactrim

47
Q

t or f: cystoisospora can lead to occasional eosinophilia

A

true (eosinophilia is an increase in disease fighting white blood)

48
Q

t or f: the lifecycle of cystoisospora is very similar to cyclospora

A

true

49
Q

what is the size of cystoisospora?

A

25-30 microns (largest of the coccidia)

50
Q

what stains can be used for cystoisospora?

A

iodine stain, modified acid fast

51
Q

t or f: cystoisospora has a typical ellipsoidal shape

A

true

52
Q

toxoplasmosis is usually self-limiting in the ________, but severe complications can arise in ____ or __________

A

immunocompetent, fetus, immunocompromised

53
Q

are the oocysts for toxoplasma immediately infectious?

A

NO (they mature in the soil)

54
Q

what is the route of entry for toxo? (2)

A
  1. undercooked meat or ingesting contaminated soil

2. gardening, handling cat litter

55
Q

t or f: toxo has a high rate of seroprevalence

A

true (22.5% of Americans have antibodies to toxo!)

56
Q

where does the sexual cycle for toxo occur?

A

in cats

57
Q

cats excrete ____, and they sporulate in soil for a few days, then become fecal oocysts..where can they go from here?

A
  1. cat eats soil and the cycle continues in them
  2. or birds/mouse eat contaminated soil or water (where they eventually forms cysts, and then the cat may eat the infected bird or mouse)
58
Q

both _____ ___ and ____ _____ transform to ______ after ingestion

A

tissue cysts, fecal oocysts, tachyzoites

59
Q

if a pregnant women becomes infected w toxo, then ______ can infect the fetus via the ______

A

tachyzoites

bloodstream

60
Q

most people who get toxo are asymptomatic, but some people get a ____-like disease

A

flu-like

61
Q

people who get toxo but are immunocompromised may get ____-enhancing ______ or _______ inflammation

A

ring, lesions, retinal

62
Q

if the fetus becomes infected w/ plasmo, it may lead to _______ or _______

A

malformations, hydrocephalus (water in brain)

63
Q

chronic toxoplasmosis occurs when a cyst is filled with ______

A

bradyzoites

64
Q

bradyzoites are metabolically ______ and are therefore very ___ dividing

A

inert, slow

65
Q

congenital toxo has the most risk during the ___ trimester because key developmental processes take place at this time

A

1st

66
Q

acute toxo can lead to…(3)

A
  1. hydrocephalus
  2. meningoencephalitis
  3. chorioretinitis
67
Q

t or f: ring-enhancing lesions are not pathognomonic

A

true

68
Q

what does igG+ mean? igM-? igM+?

A 
igG+ = previous infection at some time
igM- = no recent infection
igM = hard to interpret, b/c toxo gondii igM is present 1.5 yr after infx)
69
Q

what does it mean if the newborn is igM+?

A

new infection in baby and not from mom because only igG can pass the placenta

70
Q

name ways of diagnosing toxo (4)

A
  1. look for tissue cysts (BAL, lymph node, etc)
  2. X-ray for hydrocephalus (in new born affected)
  3. head CT (for HIV patients)
  4. amniotic fluid PCR
71
Q

how to prevent toxo?

A
  • cook meat well
  • clean cat litter daily
  • wear gloves doing garden work
72
Q

what’s unique about sarcocystis?

A

heteroxenous lifecycle

73
Q

for sarco, merogony occurs in the ____ host while gametogony occurs in the _____ host

A

intermediate, definitive

74
Q

how many species of microspora can infect humans?

A

at least 15

75
Q

what is unique about the structure of microspora?

A

polar filaments (tubule)

76
Q

what do polar filaments inject?

A

sporoplasm

77
Q

microspora causes _____ in immunocompromised people

A

diarrhea

78
Q

how is microspora diagnosed?

A

stains, histology, EM (best)

79
Q

enterocytozoon bieneusi and encephalitozoon intestinalis are names of ….?

A

microspora

80
Q

drug used to decrease microspora severity

A

albendazole

81
Q

a _____ stain can be performed with microsporidia

A

chitin

MICROM 460 (20 decks)

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