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MIMM 413 > Toxoplasmosis > Flashcards

Toxoplasmosis Flashcards

1
Q

true or false: toxo is a protozoa

A

true

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2
Q

true or false: toxo is a coccidia, microsporidia

A

-false
coccidia, sporozoa, microsporidia

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3
Q

true or false: toxo gondii is a food and waterborn parasite

A

true

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4
Q

toxo gondii: development of oocysts that are shed with…..

A

the defenitive host feces and contaminate the environment

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5
Q

when was toxo gondii first described and by who

A

1908 in Tunis by Nicolle and
Manceaux in the gundi, which is an African rodent

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6
Q

when was toxo gondii named

A

1909

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7
Q

true or false: several decades passed before we knew what toxo gondii di to humans

A

yeah

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8
Q

when was the standard test developed for giardia

A

1948, serological dye test

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9
Q

when was the life cycle for giardia first described and why who

A

start of 1970’s by frenkel and hutchinson

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10
Q

which parasite uses 2 sets of hosts for the completion of its life cycle

A

toxo

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11
Q

what are the 2 life cycle of toxo and it infects what

A

-1. ASEXUAL CYCLE IN
“INTERMEDIATE” HOSTS
Humans, cattle, rodents, pigs,
sheep, cats, etc
(all warm-blooded vertebrates)
-2. SEXUAL CYCLE IN
“DEFINITIVE” HOSTS
Cats and other Felids
via carnivorism / predation

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12
Q

which steps of toxo are in the asexual cycle

A
  1. Tachyzoites
  2. Bradyzoites in tissue cysts
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13
Q

which steps of toxo are in the sexual life cycle

A
  1. Macro- and microgametes
  2. Sporozoites in oocysts
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14
Q

contamination of toxo occurs mostky how

A

-oral route
-ingestion of raw or partly cooked meat like pork, lamb or venison who contain tissue cyst (bradyzoites)
-ingestion of oocyst contaminated cat feces through hand to mouth contact
-drinking water contaminated with oocysts
-transplacental infection in utero (tachyzoites)
-transplantation of an infected organ (bradyzoites in tissue cyst)

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15
Q

prevalence of toxo in humans

A

-up to 60% of the human population is seropositive
-Up to 60% in Québec (especially Nunavik Inuit), Nunavut, Western Europe
-depends on food habits and contact with cats

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16
Q

prevalence of toxo in animals

A
  • ~ 10% in pork
  • ~ 40% in sheep/lamb
  • 20-63% in goats
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17
Q

true or false: toxoplasmosis is usually benign

A

trye

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18
Q

how many peeps are infected by toxo

A

30-60% are infected

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19
Q

why is toxo mostly benign

A

because the immune response is super efficient

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20
Q

when are symptoms for acute toxoplasmosis show usually

A

1-3 weeks post infection

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21
Q

what is the acute stage of toxo

A

virulent tachyzoites

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22
Q

The acute stage (virulent tachyzoites) fades in a few days to weeks, leading to ……

A

the latent stage of the infection aka bradyzoite tissue cysts which is normally asymptomatic

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23
Q

when is toxo benign

A

-aids peeps
-during pregnancy

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24
Q

aids patients: toxo

A

toxoplasmosis can develop. The most notable manifestation is toxoplasmic encephalitis, which is fatal without drug treatment.

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25
Q

primary infection of toxo during pregnancy

A

possibly leading to hydrocephaly, microcephaly, intracranial calcification, and
chorioretinitis, with the possibility of miscarriage or intrauterine death. Ocular toxoplasmosis
may develop later in life.

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26
Q

infection of toxo during 1st trimester

A

incidence of transplacental infection is low (15%) but the disease in neonates is most severe.

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27
Q

infection of toxo during 3rd trimester:

A

– the incidence of transplacental infection is high (65%) but the infant
is usually asymptomatic at birth.

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28
Q

what is the symptomatic phase of toxo in aids

A

Symptomatic phase when CD4+ T cell count < 200 cells/µl due to tissue cyst
reactivation – toxoplasmic encephalitis (TE)

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29
Q

true or false: the tachyzoite of toxo is the acute phase of toxo

A

it is the acute/invasive/proliferatibe stage

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30
Q

what are the rhoptries in toxo

A

unique secretory/excretory
organelles found exclusively in the Apicomplexa.
-Important at the time of invasion and critical in the
establishment of a
productive infection

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31
Q

what are dense granules

A

secrete their contents during and after invation
-major t cell antigen for class 1 mhc

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32
Q

true or false: in toxo they have stage specific surface antigens

A

-true they are known as adhesins

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33
Q

in toxo: GPI-anchored proteins, which act as redundant
receptors for binding to…

A

sulf proteoglycans on various host cells

34
Q

what is the dormant stage of toxo

A

-the bradyzoite
-aka the dormant stage

35
Q

true or false: bradyzoite looks like tachyzoite

A

true
-But distinct antigenically and physiologically (different set of SAG surface antigens)

36
Q

what are the reserve of carbohydrates for toxo

A

amylopectin granules

37
Q

bradyzoites of toxo live where and are derived from what

A
  • in tissue cysts,w hich are derived from a parasitophorous vacuole and a cyst wall
38
Q

how big are bradyzoites

A

10-200 um

39
Q

the dormant stahe of toxo is found where

A

found in muscles (infective stage), brain

40
Q

unlike tachyzoite in toxo, bradyzoites are resistant to what

A

low ph and host digestive proteases in the stomach

41
Q

The transition from tachyzoite to bradyzoite is associated with morphological changes:….

A

narrowing of the parasite body, movement of the nucleus toward the parasite posterior, an increase in
the number of micronemes (blue) and amylopectin granules (white), and more electron-dense
rhoptries (maroon).

42
Q

one stress response pathway in toxo linked to stage conversion involves what

A

phosphorylation of the alpha subunit of eukaryotic initiation factor-2 (TgIF2α), which is mediated by stress-activated TgIF2α kinases (TgIF2Ks).

43
Q

what is the sexual stage for toxo

A

the sporozoite/oocyst

44
Q

how big is the toxo ooxyst

A

13um in size

45
Q

the oocyst of toxo is resistant stage viable in moist soil for …

A

18 months

46
Q

the oocyst is a product of what

A

-product of sexual cycle (micro- and macrogametes), which occurs in the intestinal cells
of definitive hosts (cats)

47
Q

oocyst in toxo are passed out in the feces of …

A

s by definitive
hosts/carnivores (cat) feces-10-14 days after infection

48
Q

true or false: in toxo, each oocysts contain 4 sporocysts

A

false, it is 2

49
Q

true or false: oocysts are infective to humans and other herbivore hosts

A

true

50
Q

oocysts of toxo are resistant to what

A

Physical agents
UV, dessication, freezing
Chemical agents
Ozone, bleach, iodine, ethanol, formalin, salts

51
Q

persistence of oocysts toxo

A

18 months in soil
54 months in water

52
Q

true or false: is unsporulated and non-infectious when excreted

A

true

53
Q

what do toxo oocysts contain

A

it contains a single, undifferentiated cytoplasmic mass and is essentially the zygote stage of the parasite surrounded by a protective
wall

54
Q

in toxo: sporulation occurs by what

A

meiotic division

55
Q

meotic division in toxo oocysts

A

During this process, the cytoplasm divides into a characteristic number of sub-masses (secondary
sporoblasts), which develop a resistant wall and are termed sporocysts. Within the sporocysts, the infectious stages (sporozoites) are formed. The sporozoites are thus protected by both the oocyst and sporocyst walls

56
Q

how many sporozoites are in a sporocyst

A

4

57
Q

true or false: can shed oocysts in their feces for several weeks after the initial contamination

A

true

58
Q

how long do oocysts of toxo can become infectuous

A

1-2 days

59
Q

how many % of cats shed oocyst at any one time

A

2%

60
Q

oocyst of toxo shedding does not recur after….

A

even after repeated exposure to the parasite

60
Q

true or false: toxo oocysts have been detected on cat fur and in their infectuous form

A

false: in their non infectuous form

61
Q

when was the outbreak of toxo in bc

A

1995 on vancouver island

62
Q

which parasite is a significant cause of death of sea otters

A

toxo
-38% of lil sea otters had toxo

63
Q

true or false: toxo is a threat for the safety of public water supplies

A

true

64
Q

what is the type of immune response to toxo

A

controlled by cell mediated immunity
-cd8 are the major effectors
-cd4 are important for regulation of immune response
-nk and macrophages are the first line of defense

65
Q

what cytokine is important for th1 response to toxo gondii

A

il12
-you also have infy to kill intracellular parasites

66
Q

true or false: it is hard to show that someone is infected by toxo

A

yeah because it is intracellular

67
Q

how is toxo diagnosed

A

Acute infection is assessed by serology (IgG & IgM)
IgG antibodies usually appear 1 to 2 weeks after the
initiation of infection, reaching peak titers in 6 to 8 weeks,
then gradually decline over 1 to 2 years.

68
Q

how are the titers for toxo

A

-usually low
-persists for life

69
Q

true or false: toxo titers correlates with disease severity

A

false it does not

70
Q

how is acute infection of toxo diagnosed?

A

-serology
-elisas are available and now preferred

71
Q

intra-uterine and cerebral disease of toxo can be diagnosed how

A

pcr

72
Q

treatment of toxo acute

A

-pyrimethamine
-sulfadiazine
-clindamycin
-spiramycin

73
Q

treatment of toxo chronic

A

-tissue cyst are resistant to most treatment
-atovaquone
-clindamycin

74
Q

why is toxo so sucessful

A

-it is protected from many immune effector mechanisms because it is intracellular
-can infect any nucleated cell in any warm blooded vertebrate

75
Q

the vacuole of toxo are resistant to what

A

fusion with the host cell lysosomes

76
Q

true or false: t gondii manipulated host cell processes

A

true

77
Q

what does T gondii manipulate

A

host cells and immune effectors

78
Q

why are toxo hosts rarely killed

A

A balanced host-parasite interaction is established
and is necessary for T. gondii survival, persistence and transmission

79
Q
A

MIMM 413 (24 decks)

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