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IMP Parasitology > 20. Protozoa (Trypanosomes) > Flashcards

20. Protozoa (Trypanosomes) Flashcards

1
Q

what are the african Trympanosomes?

A

T. brucei gambiense

T. brucei rhodesiense

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2
Q

what is the american Trympanosome?

A

T. cruzi

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3
Q

which disease is caused by T. cruzi?

A

Chagas disease

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4
Q

which disease is caused by T. brucei?

A

african sleeping sickness

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5
Q

which vector is associated with/can transmit the parasite that causes the disease African sleeping sickness?

A

Tsetse fly of the genus Glossina

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6
Q

which parasite causes West african sleeping sickness?

A

T. b. gambiense

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7
Q

which parasite causes East african sleeping sickness?

A

T. b. rhodesiense

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8
Q

what are the two subspecies of T. brucei?

A
  • gambiense

- rhodesiense

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9
Q

can the two subspecies of T. brucei be differentiated morphologically?

A

no

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10
Q

what is another subspecies that exists of T. brucei? does it infect humans?

A
  • T. b. brucei

- no

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11
Q

what animals do T. brucei brucei infect?

A

it is a parasite of antelopes and other African ruminants (cattle, horses, camels) and are pathogenic to domestic ruminants

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12
Q

what disease does T. b. b. cause in animals?

A

Nagana, a type of african sleeping sickness in animals

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13
Q

what is the phenotype caused by T. b. b.?

A

reduced growth rate, milk productivity, and strength of farm animals, leading to the eventual death of the infected animals

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14
Q

which vector is associated with/can transmits the parasite that causes Chagas disease?

A

Triatoma

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15
Q

what are the Trypanosome parasites of equines?

A

T. equinum

T. equiperdum

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16
Q

what is the disease that is caused when horses are infected with an equine trypanosome?

A

Dourin

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17
Q

what is the vector for Equine Trypanosomes?

A

none, it is transmitted through direct blood contact by biting during copulation, or by biting insects such as horse flies

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18
Q

which trypanosome infects camels?

A

T. evansi

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19
Q

what is the disease that is caused when camels are infected with the camel trypanosome?

A

Surra

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20
Q

which vector is associated with/can transmits the parasite that causes the disease Surra?

A

Tabanids

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21
Q

who is the main reservoir for T. brucei gambiense?

A

humans

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22
Q

who is the main reservoir for T. brucei rhodesiense?

A

wild game animals and cattle

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23
Q

what are the ways that Trypanosoma brucei can be transmitted?

A
  • mother to child, across the placenta
  • blood transfusion
  • sexual contact
  • laboratories: accidental infections, although this is uncommon
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24
Q

Where is T. b. gambiense found?

A

central and west Africa

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25
Q

where is T. b. rhodesiense found?

A

in southern and eastern Africa

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26
Q

what kind of infection does T. b. gambiense cause?

A

a chronic infection

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27
Q

what kind of infection does T. b. rhodesiense cause?

A

an acute infection

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28
Q

how long does it take for an infection of T. b. rhodesiense to emerge?

A

a few weeks

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29
Q

which parasite, T. b. gambiense or rhodesiense causes the more virulent and faster developing disease?

A

T. b. rhodesiense

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30
Q

what is special about the African Trypanosome life cycle?

A

the whole life cycle has extracellular stages

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31
Q

what does an infected Tsetse fly inject into the skin tissue during a blood meal in African Trypanosomes?

A

metacyclic trypomastigotes

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32
Q

what is the infective stage of the African Trypanosome?

A

metacyclic trypomastigotes

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33
Q

how do the African Trypanosome parasites get to the blood?

A

through the lymph

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34
Q

what do the metacyclic trypomastigotes transform into in African Trympanosomes and where in the host?

A

bloodstream trypomastigotes

inside the host blood stream

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35
Q

where do the bloodstream trypomastigotes go in the body in African Trympanosomes?

A

to other sites throughout the body, in other fluids, lymph, spinal fluid

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36
Q

how do the bloodstream trypomastigotes multiply in the fluids in African Trympanosomes?

A

by binary fission

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37
Q

what are the intracellular stages of the African Trypanosome life cycle?

A

THERE ARE NONE

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38
Q

what occurs to the bloodstream trypomastigote in the midgut of the Tsetse fly?

A

they transform into the procyclic trypomastigotes, multiply by binary fission and transform into epimastigotes

39
Q

where do the epimastigotes go?

A

they make their way to the fly’s mouth in the salivary glands and continue multiplication by binary fission

40
Q

what do the epimastigotes in African Trympanosomes transform into?

A

metacyclic trypomastigotes and start the cycle again

41
Q

what is antigenic variation?

A
  • Antigen variation is the process of a parasite changing its surface protein.
  • Trypanosomes use the antigen variation of variant surface glycoproteins (VSGs)
42
Q

what is beneficial about changing the surface glycoproteins?

A

Change in the antibody epitopes displayed by the pathogen allows escape from antibody mediated responses

43
Q

what type of infection do the VSGs allow?

A

chronic infection

44
Q

around how many vsg genes does the genome of a Trypanosome contain?

A

over 1000

45
Q

what happens within the genome to change the expression of the surface proteins?

A

different VSGs are inserted into a single expression site

46
Q

what is the theory behind the slender vs stumpy forms?

A

So in the slender form they have one specific VSG and in the process of growing to the stumpy form they start changing the VSG, so that by the time they are stumpy forms they would have a different VSG and that’s why you would have high amount of stumpy form at that point

47
Q

what does T. brucei gambiense invade? what does this cause?

A

the central nervous system, initiating a chronic, sleeping-sickness

48
Q

what are the symptoms of the sleeping sickness caused by T. brucei gambiense?

A
  • apathy, mental dullness, tremor of hands, tongue, etc. followed by convulsions and paralysis
  • sleeping followed with coma and death common.
49
Q

does T. brucei rhodesiense attach the nervous system?

A

no

50
Q

what are the symptoms of T. brucei rhodesiense?

A
  • causes a more rapid death
  • rapid weight loss, heart involvement, and death can occur within a few months
  • Winterbottom’s sign (swelling of lymph nodes along the back of the neck)
51
Q

how is African Trypanosomiasis diagnosed?

A
  • by finding the trypomastigote stages, which are only found in humans , in the microscopic examination of lymph node aspirates, blood, bone marrow, or, in the late stages of infection, cerebrospinal fluid
52
Q

how is the blood smear prepared and examined in African Trympanosomes?

A

A wet preparation should be examined for the motile trypanosomes, and a smear should be fixed, stained with Giemsa and examined under the microscope

53
Q

do Tsetse flies lay eggs?

A

no, they are larviparous

54
Q

what kind of soil do the pupa occur in?

A

in dry soil in open country

55
Q

how do we control tsetse flies?

A
  • chemical spraying of insecticides
  • elimination of wild game animals
  • selective breeding of cattle
56
Q

what is relevant about the slender and stumpy forms of VSGs?

A

in the slender form they have one specific VSG and in the process of growing to the stumpy form they start changing the VSG, so that by the time they are stumpy forms they would have a different VSG and that’s why you would have high amount of stumpy form at that point

57
Q

is American Trympanosomiasis a zoonosis?

A

yes

58
Q

how is T. cruzi transmitted to humans?

A

by blood sucking triatomine bugs

59
Q

which are the common genera for the triatomine vector in American Trypanosomiasis?

A

Triatoma
Rhodinisus
Panstrongylus

60
Q

what is another name for American Trypanosomiasis?

A

Kissing bug

61
Q

what are some alternative methods of transmission of T. cruzi?

A
  • blood tranfusions
  • organ transplant
  • transplacentally
  • in labs
62
Q

what should American Trypanosomiasis be called?

A

Latin American Trypanosomiasis

63
Q

How does transmission occur via the triatomine bug?

A

it defecates on the wound after a blood meal and then you scratch it into the wound

64
Q

what is the infective stage of the American Trypanosome?

A

the metacyclic trypomastigotes, they are ejected in the feces and into the wound made by the blood meal bite

65
Q

where are possible sites of entry for the parasite in American Trypanosomes?

A

through wounds or intact mucous membranes

66
Q

where do the trypomastigotes go in the host in American Trypanosomes?

A

they invade cells neat the site of inoculation, where they differentiate into intracellular amastigotes

67
Q

how do the amastigotes multiply in the cells in American Trypanosomes?

A

binary fission

68
Q

what do the amastigotes differentiate into in American Trypanosomes and what happens to those?

A

they differentiate into trypomastigotes and are released into circulation as bloodstream trypomastigotes

69
Q

what kind of tissues do trypomastigotes infectin American Trypanosomes?

A

a variety of tissues

70
Q

what do the trypomastigotes differentiate into at the new tissue they arrive at in American Trypanosomes?

A

intracellular amastigotes

71
Q

do the bloodstream trypomastigotes replicate in American Trypanosomes?

A

no

72
Q

when does replication continue after bloodstream trypomastigoes in American Trypanosomes?

A

only when parasites enter another cell

73
Q

when does the “kissing bug” become infected in American Trypanosomes? what stage does it get infected by?

A

during a blood meal - gets infected by the bloodstream trypomastigotes

74
Q

what tranformation does the Ameircan Trypanosome trypomastigote undergo in the kissing bug’s midgut?

A

transforms into the epimastigote

75
Q

what tranformation does the Ameircan Trypanosome trypomastigote undergo in the kissing bug’s hindgut?

A

from the epimastigote to the metacyclic trypomastigote

76
Q

in what kind of organs does African trypanosomiasis infect?

A

hallow organs

77
Q

how long is one infected with African Trypanosomes?

A

typically for life

78
Q

what is the major contributor to the pathological consequences?

A

cell death

79
Q

what is the most recognized marker of acute chagas disease?

A

Romana’s sign

80
Q

what is Romana’s sign?

A

swelling of the eyelids on the side of the face near the bite wound or where the bug feces were deposited or accidentally rubbed into the eye

81
Q

what are the symptoms in the early, acute stages of American Trypanosomiasis?

A

symptoms are mild and usually produce no more than local swelling at the site of infection

82
Q

what are the symptoms in the stages of American Trypanosomiasis over the course of many years?

A

serious chronic symptoms can appear, such as heart disease and malformation of the intestines

If untreated, the chronic disease can be fatal

83
Q

what is the feature of the chronic phase of infection?

A

one is immune to reinfetion but parasites are not eliminated from the body

84
Q

how many patients with American Trypanosomiasis are asymptomatic?

A

41%

85
Q

how many patients with American Trypanosomiasis have cardiomyopathy? how many of these have sudden death?

A

45%

58%

86
Q

how many patients with American Trypanosomiasis get megaesophagus?

A

11%

87
Q

how many patients with American Trypanosomiasis get megacolon?

A

~3%

88
Q

which stages of the American Trypanosome parasite are found in humans?

A

amastigotes

trypomastigotes

89
Q

how is diagnosis of American Trypanosomiasis done?

A

Microscopic examination of:

a) fresh blood for motile parsites
b) of thin and thick blood smears stained with Giemsa for visualization of parasites

90
Q

which stage is free swimming in the blood in American Trypanosomisasis?

A

trypomastigotes

91
Q

is there a vaccine against Chagas disease?

A

nop

92
Q

what is the focus of prevention of Chagas disease?

A

fighting the vector - using paints and insecticides and improving houses and sanitary conditions in rural areas, mosquito nets also

93
Q

what is the second most common transmission route of Cagas disease in many latin countries? is this under control?

A

blood transfusion - in most countries testing of blood donors is mandatory, but not in developed countries because Chagas disease is not endemic

IMP Parasitology (27 decks)

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