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IMP Parasitology > 19. Protozoa (Leishmania) > Flashcards

19. Protozoa (Leishmania) Flashcards

1
Q

who is in the class kinetoplastida?

A
  • leishmania

- trypanosoma

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2
Q

what unique feature do kinetoplastids have?

A

the unique organelle, the kinetiplast

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3
Q

what is a kinetoplast?

A

a disk shaped mass of circular DNA inside a large mitochondrion that contains many copies of the mitochondrial genome

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4
Q

how does kinetoplast DNA look?

A

it is relatively abundant and is a tighly packed mass of DNA

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5
Q

the kinetoplastid genome is composed of ______.

A

ktDNA

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6
Q

the two types of ktDNA occur in a _________ and are called ______ and _______.

A

linked mass within the mitochondrion

mini-circles; maxi-circles

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7
Q

what do maxi circles encode?

A

mitochondrial genes and they are more or less equivalent to the mtDNA

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8
Q

mini-circles are ________ and rapidly evolving, and their function is less clear.

A

heterogenous

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9
Q

what do mRNAs expressed from maxi-circles require?

A

extensive RNA editing

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10
Q

what is RNA editing in maxi-circles mediated by?

A

several multi-protein complexes but the information comes from small guide RNAs that are encoded on mini-circles

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11
Q

what is special and novel about kinetoplastid DNA?

A

that there are 2 genomes in the mitochondrion, one of which contains sequence information that corrects errors in the other

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12
Q

how are the errors on the maxi-circles corrected?

A

they need to be edited

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13
Q

where does editing of the maxi-circles take place?

A

in the mitochondrion of kinetoplastids

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14
Q

what does the extent of editing correlate with?

A

the stage in the parasitic life cycle and the corresponding metabolic changes - such as aerobic/anarobic

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15
Q

what is mini-circle DNA used for in practice?

A

parasite detection and differentiating between various isolates

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16
Q

what is a glycosome?

A

a peroxisome-like organelle in which glycolysis occurs (conversion of glucose to pyruvate)

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17
Q

how many membranes does a glycosome have?

A

1

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18
Q

what does the glycosome change in comparison to other eukaryotic organisms?

A

it sequesters a large number of glycolytic enzymes that would otherwise be located in the cytosol

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19
Q

the glycosome of kinetoplastids shares some enzymes with _________ and __________ of other protists, plants and animals.

A

peroxisomes; glyoxysomes

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20
Q

what are the four major morphological forms of kinetoplastids, which are associated with the different life cycle stages in various species that cause disease in humans?

A
  • trypomastigote
  • amastigote
  • promastigote
  • epimastigote
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21
Q

where is the kinetoplast located in the trypomastigote?

A

on the posterior

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22
Q

where is the flagellum in a trypomastigote?

A

it emerges from the posterior end of the parasite (basal body, bb) and extends the length towards the anterior where the extension of the free flagellum emerges from the anterior end

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23
Q

how long is the undulating membrane in a trypomastigote?

A

it spans the length of the parasite

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24
Q

what is the use of the undulating membrane trypomastigote?

A

it functions like a fin and increases the motility of the organism

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25
how does the amastigote look like?
spherical in shape and no free flagellum
26
the _____ and the ______ are present in the amastigote
basal body; base of the flagellum
27
what is the kinetoplast identified as in microscopy
a dark staining body near the nucleus
28
is the amastigote motile?
no
29
what is the morphology of the promastigote?
the kinetoplast is towards the anterior and a free flagellum with no undulating membrane emerges where it will pull the organism from
30
what is the morphology of the epimastigote?
The kinetoplast is more centrally located, usually just anterior to nucleus, and the flagellum emerges from the middle and forms a shorter undulating membrane than in trypomastigotes
31
who is noticeably more motile, epimastigotes or trypomastigotes?
trypomastigotes
32
what are the 4 types of leishmaniasis?
- cutaneous leishmaniasis - mucosal leishmaniasis - visceral leishmaniasis - nodular post-kala-azar dermal leishmaniasis (PKDL)
33
how is Leishmania spp. transmitted
by the bite of certain species of sandflies - Phlebotomus (old world) - Lutzomia (new world)
34
most forms of Leishmania are only spread through ______ but some can be spread between humans
animals, as a zoonosis
35
how many species of Leishmania cause human infection
21/30 that can infect mammals
36
how are different species of Leishmania distinguished?
they are morphologically indistinguishable, they can be distinguished by isoenzyme analysis, DNA seq analysis, or monoclonal antibodies
37
which parasite causes visceral leishmaniasis?
L. donovani
38
which parasites cause cutaneous leishmaniasis?
L. tropica; (L. t. major, minor and ethiopia)
39
which parasite causes mucocutaneous leishmaniasis?
L. braziliensis, also L. mexicana and L. peruviana
40
what is visceral leishmaniasis also called?
Kala-azar, black fever, dum-dum fever
41
what is cutaneous leishmaniasis also called?
oriental sore, Delhiulcer, Aleppo, Delhi or Baghdad boil
42
what is mucocutaneous leishmaniasis also called?
espundia, Uta, chiclero ulcer
43
how many countries is leishmaniasis found in?
88
44
what kind of life cycle does Leishmania have?
a digenetic one; with 2 hosts
45
what are the 2 morphological forms of Leishmania?
- promastigote- in the sandfly vector | - amastigote- in the host (e.g. human)
46
where is Leishmania found in cutaneous leishmaniasis?
intracellularly in macrophages in skin lesions
47
where is leishmania found in visceral leishmaniasis?
in the mononuclear phagocyte system of blood, liver, lymph nodes, spleen
48
what are the features of the promastigote stage of leishmania?
- insect stage - motile - midgut
49
what are the features of the amastigote stage of leishmanis?
- mammalian stage - non-motile - intracellular
50
where does sexual reproduction occur for Leishmania?
in sand flies, the natural vector of leishmania
51
how is leishmania transmitted?
the bite of the infected female sandfly
52
which stage do the sandflies inject into the host during their blood meals?
the infective stage - the promastigotes
53
what part of the sandfly transmits the parasite?
the proboscis
54
what happens to promastigotes that reach the puncture wound?
they are phagocytised by macrophages and other types of mononuclear phagocytic cells
55
what do promastigotes transform into in the phagocytes?
into the tissuestage - the amastigotes
56
how do amastigotes multiply?
by simple division
57
what do amastigotes do after multiplying?
proceed to infect other mononuclear phagocytic cells
58
what is the pathogenesis of leishmaniasis due to?
an immune reaction to the pathogen, particularly cell-mediated immunity
59
what does lab examination of the blood show in leishmaniasis?
- marked decrease in white blood cells - relative increase in monocytes and lymphocytes - reduced platelets - anemia - IgM and IgG levels are extremely elevated
60
why are IgM and IgG antibodies extremely elevated?
due to both specific antibodies and polyclonal activation
61
what is seen in clinical disease of cutaneous leishmaniasis?
- it is generally self-healing - seen in skin - mucous membranes
62
what is seen in the clinical disease of visceral leishmaniasis?
- it is fatal, up to 90% if untreated - liver - spleen - bone marrow
63
what causes cutaneous leishmaniasis in the old world?
L. tropica L. major L. ethiopia
64
what causes cutaneous leishmaniasis in the new world?
L. mexicana
65
which is the most common form of leishmaniasis?
cutaneous
66
how is cutaneous leishmaniasis characterized?
one or more sores, papules, or nodules on the skin
67
what are the sores of cutaneous leishmaniasis often described as?
a volcano with a raised edge and central crater
68
what may be observed near the sores?
swollen lymph nodes
69
where are the swollen lymph nodes if the sore is on the arm or the hand?
under the arm
70
how long after the bite is a nodule produced?
2-8 weeks
71
is the papule painful?
no, relatively painless
72
the center of the papule _____ while _____ develop at the periphery
encrusts; satellite papules
73
how long the the ulcer take to heal?
2-10 months - but leaves a scar
74
which parasite causes mucocutaneous leishmanisis?
L. braziliensis
75
what are the clinical features of mucocutaneous leishmaniasis?
- the same as those of cutaneous leishmaniasis, except that in this disease the organism can metastasize and the lesions spread to mucoid tissues (oral, pharyngeal and nasal) and lead to their destruction and hence sever deformity.
76
how long after the original skin lesion can the deformities occur in mucocutaneous leishmaniasis?
months to years after
77
which parasite causes visceral leishmaniasis?
- L. donovani and L. d. infantum in the old world | - L. donovani chagasi in the new world
78
who does L. donovani infect?
people of all ages
79
who does L. d. infantum infect?
young children as well as infants
80
where is visceral leishmaniasis usually the least severe?
from the Middle East
81
what is usually associated with visceral leishmaniasis?
fever, weight loss, and an enlarged spleen and liver
82
why is there usually a delay in diagnosis of visceral leishmaniasis?
because the symptoms are not specific
83
when should visceral leishmaniasis always be considered?
in patients with a chronic fever whom are from an endemic area
84
what is the causative organism of New World visceral leishmaniasis?
L. d. chagasi
85
why is there rarely a local lesion in visceral leishmaniasis?
because the L. donovani organisms are rapidly eliminated from the site of infection
86
where do the parasites multiply in visceral leishmaniasis
in the mononuclear phagocytic cells of the spleen, live, lymph nodes, bone marrow, intestinal mucosa and other organs
87
what are the symptoms 1-4 months after infection in visceral leishmaniasis?
- occurrence of fever with a daily rise to 39-40°C, +chills and sweating - the spleen and liver progressively become enlarged
88
what is the issue with chronic disease?
it renders patients susceptible to other infections
89
what happens in untreated disease?
result is death
90
what can happen to the hands/skin of a patient with visceral leishmaniasis?
jaundice
91
how is diagnosis done for leishmaniasis?
- based on a history of exposure to sandflies - synmptoms - isolation of the organisms from the lesion aspirate or biopsy, by direct examination or culture
92
what is done in the laboratory?
the use of a biopsy, and examination of Giemsa stained slides of the relevant tissue is the most common technique
93
what is antibody detection good for? what is it not useful for?
useful in visceral leishmaniases limited value in cutaneous disease
94
what methods exist for parasite detection/species identification?
biochemical (isoenzymes) immunological (immunoassays) molecular (PCR)

IMP Parasitology (27 decks)

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