PARASITOLOGY Flashcards

1
Q

Symbiosis

A

living together of phylogenetically different organisms

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2
Q

Mutualism

A

beneficial to both organisms

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3
Q

Commensalism

A

beneficial to one organism, neutral to the other

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4
Q

Parasitism

A

beneficial to one organism, harmful to the other

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5
Q

Definitive Host

A

harbors the adult or sexual stage of a parasite

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6
Q

Examples of Definitive Host

A
  1. Cat - DH of T. gondii
  2. Mosquito (Female anopheles) - DH of Plasmodium spp.
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7
Q

Intermediate Host

A

Harbors the larval or asexual stage of a parasite

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7
Q

Examples of Intermediate Host

A
  1. Mosquitoes - IH of Filarial worms
  2. Snail - IH of ALL trematodes (schistosomes and hermaphrodites)
  3. Man - IH (accidental) host of Echinococcus spp. (Dog is DH)
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8
Q

Paratenic Host

A

Harbors a parasite that does not develop but remains alive and if infective to the next host. Carries or bridges the parasite to the next host.

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8
Q

Examples of Paratenic Host

A
  1. Large fish - PH of D. Latum
  2. Snake, bird - PH of G. spinigerum
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9
Q

Obligate Parasite

A

Depends entirely upon its host for existence. MOST PARASITES ARE OBLIGATE PARASITES.

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9
Q

Reservoir

A

Allows the parasite’s life cycle to continue and serves as a source of human infection

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9
Q

Example of Reservoir

A
  1. Pig - RH of B. coli (also considered zoonotic)
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10
Q

Facultative Parasite

A

Capable of parasitic and free-living existence

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11
Q

Examples of Facultative Parasite

A
  1. S. stercoralis
  2. FLAs (Naegleria, Acanthamoeba spp.)
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12
Q

Classification of parasite according to number of host required

A

Transitory, Permanent, Periodic

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13
Q

Transitory parasite

A

Larval stage is passed in a host while the adult is free living in only 1 host

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14
Q

Example of transitory parasite

A

S. stercoralis (INDIRECT LIFE CYCLE ONLY)

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15
Q

Permanent parasite

A

Completes its life cycle in 1 host for all the life stages

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16
Q

Example of permanent parasite

A

H. nana - the only cestode that is capable of this. Also called monoxenous or homoxenous (DIRECT LIFE CYCLE ONLY)

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17
Q

Periodic parasite

A

Requires 2 or more hosts (heteroxenous) for the larval and adult stages

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18
Q

Example of periodic parasite

A

Trematodes and cestodes (Except H. nana)

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19
Q

Zoonotic parasite

A

Primarily infects animals and may be acquired by man and causes infection in man

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20
Q

Examples of zoonotic parasite

A
  1. B. coli
  2. D. immitis
  3. Agents of larva migrans
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21
Q

Accidental parasite

A

Occurs in an unusual host

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22
Q

Examples of accidental parasites

A
  1. Echinococcus
  2. Agents of larva migrans (maturation is arrested at larval stage - meaning life cycle will not continue)
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23
Q

Erratic parasite

A

Occurs in an unusual organ or habitat

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24
Q

Example of erratic parasite

A
  1. A. lumbricoides - can cause ectopic ascariasis (it is supposed to be in the small intestine)
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25
Q

Spurious or coprozoic parasites

A

Passes through the intestinal tract without causing any disturbance (DON’T CAUSE INFECTION)

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26
Q

Examples of spurious or coprozoic parasite

A
  1. F. hepatica unembryonated eggs - not infectious, metacercaria is the infective stage in man
  2. C. hepatica unembryonated eggs
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27
Q

Endoparasite

A

Lives inside the body of a host (MOST PARASITES ARE ENDOPARASITES)

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28
Q

What is it called when an endoparasite invades a host?

A

INFECTION

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29
Q

Ectoparasite

A

Lives on body surfaces

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30
Q

What is it called when an endoparasite invades a host?

A

INFESTATION

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31
Q

Examples of ectoparasites

A
  1. Lice (Pediculus humanus capitis, P. h. humanus, Phthirus pubis)
  2. Itch mite (Sarcoptes scabei)
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32
Q

Intermittent parasites

A

Visits the host only during feeding time

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33
Q

Examples of intermittent parasite

A
  1. Bed bug
  2. Mosquito
  3. Flea
  4. Tick
  5. Biting fly
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34
Q

Arthropods are considered as?

A

Ectoparasite, Intermittent parasite, vectors

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35
Q

Biologic Vector

A

transmits a parasite only after the latter has completed part of its development; may also serve as a host

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36
Q

Mechanical or Phoretic

A

not essential in the parasite’s life cycle and is responsible only for transporting the parasite via appendages or external surfaces

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37
Q

Examples of biological vectors

A

Mosquitoes
Biting flies
Kissing bugs
Ticks

38
Q

Parasites transmitted by mosquitoes

A

Plasmodium spp., W. bancrofti, B. malayi

39
Q

Parasites transmitted by biting flies

A

Leismania spp., T. brucei, Loa loa, Oncocerca

40
Q

Parasites transmitted by kissing bugs (Reduviid or Triatomine)

A

T. cruzi

41
Q

Parasites transmitted by ticks (Ixodes)

A

Babesia spp.

42
Q

Examples of mechanical vectors

A

Cockroaches
House flies

43
Q

Cockroaches and house flies are:

A

Mechanical vectors of A. lumbricoides and other enteric parasites (stool and soil)

44
Q

Portal of Entry: Mouth/oral cavity
MOT: Ingestion
Example: ________

A

Most intestinal parasites

45
Q

Portal of Entry: Mouth/oral cavity
MOT: Oral-anal intercourse
Example: ________

A

G. lamblia, E. histolytica, C. parvum, D. fragilis, E. vermicularis

46
Q

Portal of Entry: Skin
MOT: Larval skin penetration
Example: ________

A
  1. Hookworms
  2. S. stercoralis
  3. Schistosoma spp.
47
Q

Portal of Entry: Skin
MOT: Skin inoculation (vector-borne)
Example: ________

A
  1. Plasmodium spp.
  2. Filariae
  3. Babesia spp.
  4. Leismania spp.
  5. Trypanosoma spp.
48
Q

Portal of Entry: Urogenital tract
MOT: Sexual intercourse (venereal)
Example: ________

A

T. vaginalis

49
Q

Portal of Entry: Nasal passages
MOT: Intranasal
Example: ________

A

FLAs (Naegleria and Acanthamoeba spp.)

50
Q

Portal of Entry: Transplacental
MOT: Vertical transmission (mother to fetus)
Example: ________

A
  1. T. gondii
  2. T. cruzi
  3. Plasmodium spp.
51
Q

Autoinfection can either be:

A

internal or external

52
Q

Internal autoinfection

A

within the intestine

53
Q

Examples of internal autoinfection

A
  1. S. stercoralis - rhabditiform transforms into filariform in the intestine
  2. C. philippinensis - atypical females
  3. C. parvum
  4. T. solium - reverse peristalsis of eggs (cysticercosis, can be fatal!)
54
Q

External autoinfection

A

hand to mouth

55
Q

Examples of external autoinfection

A
  1. E. vermicularis
  2. H. nana
56
Q

Portals of exit

A

Anus
Mouth
Urogenital tract
Skin

57
Q

Who coined the binomial system of nomenclature?

A

Carl Linnaeus

58
Q

Genus

A

represents the taxon to which the species belongs; first letter is capitalized

59
Q

Specific epithet

A

trivial name that distinguishes the species within the genus

60
Q

Protozoa

A

unicellular eukaryotes

61
Q

Phylum Sarcomastigophora

A

Amoebae and flagellates

62
Q

Phylum Ciliophora

A

Ciliates (B. coli)

63
Q

Phylum Apicomplexa

A

Sporozoans and coccidians

64
Q

Similarity between Phylum Sarcomastigophora and Ciliophora

A

Asexual reproduction
Locomotory organelles

65
Q

Characteristics of Phylum Apicomplexa

A

Sexual and asexual reproduction
Generally nonmotile

66
Q

Other unicellular (not true protozoa) parasites include:

A
  1. Blastocystic spp. - stramenophiles
  2. Microsporidians - Encephalitozoon spp., enterocytozoon spp. (obligate intracellular fungi; smallest intestinal parasites (1.5 - 3 um)
  3. Pneumocystis jirovecii - atypical fungus
67
Q

Classification of helminths

A

Phylum Nemathelminthes
Phylum Platyhelminthes

68
Q

Phylum Nemathelminthes

A

Nematodes (roundworms) - non hermaphroditic

69
Q

Phylum Platyhelminthes

A

Tramatodes (flukes) - hermaphrodites (monoecious flukes) and non-hermaphrodites (schistosomes)
Cestodes (tapeworms) - hermaphroditic

70
Q

Classification of arthropods

A

Class Arachnida
Class Insecta
Class Crustacea

71
Q

Class Arachnida

A

Ticks
Mites
Chiggers (bacteriology - mite larvae)

72
Q

Class Insecta

A

Mosquitoes
Flies
Midges
Bugs
Lice
Fleas & Beetles (IH of Hymenolepsis and D. caninum)
Cockroaches (Mechanical vector of A. lumbricoides)

73
Q

Class Crustacea

A

Crabs and crayfish (2nd IH of P. westermani)
Copepods - cyclops, Diaptomus spp. (IH of D. medinensis, G. spinigerum; 1st IH of D. latum and Spinometra)

74
Q

Clearance period of antacids, antidiarrheals, barium, bismuth, laxatives (leave crystalline residues)

A

7-10 days

75
Q

Clearance period of antimicrobial agents

A

2-3 weeks

76
Q

Clearance period of gallbladder dyes

A

2 weeks

77
Q

Sufficient quantity of stool specimen

A

2-5 grams (thumb sized) - formed
5-6 tbsp - liquid

78
Q

What should the label contain in a stool specimen?

A

Patient’s name, age, sex, date and time of collection

79
Q

Number of specimens to be examined for stool in parasitology:

A

3 spx collected on separate days within a 10 day period (to recover the parasites that shed diagnostic forms intermittently - e.g. G. lamblia, S. stercoralis)

80
Q

Liquid stool specimens must be processed or preserved within

A

30 mins

81
Q

Soft/semi-formed stool specimens must be processed or preserved within

A

1 hour

82
Q

Formed stool specimens must be processed or preserved

A

up to 24 hours but must be refrigerated

83
Q

For longer periods of preservation:

A

2-vial system - 1 part 10% formalin, 1 part PVA

84
Q

Ratio of stool to preservative:

A

1 stool : 3 preservatives

85
Q

10% formalin is an

A

All-purpose fixative

86
Q

10% formalin can be used in:

A

WM (Wet Mount)
CT (Concentration Technique)
IA (Immunoassay)

87
Q

Merthiolate-iodine-formalin can:

A

Fix and stain

88
Q

Merthiolate-iodine-formalin can be used in:

A

WM (Wet Mount)
CT (Concentration Technique)

89
Q

Sodium acetate-acetic acid formalin:

A

Can be used for permanent stains

90
Q

Sodium acetate-acetic acid formalin can be used in:

A

WM (Wet Mount)
CT (Concentration Technique)
Permanent Staining (PS)

91
Q

Schaudinn’s fluid w/o PVA contain:

A

Mercuric Chloride (toxic to man)

92
Q

Schaudinn’s fluid w/o PVA can be used in:

A

Permanent Staining (PS)

93
Q

PVA (SF w/ PVA) contain:

A

Mercuric Chloride (toxic to man)

94
Q

PVA (SF w/ PVA) can be used in:

A

Permanent Staining (PS)

95
Q

Modified PVA may be used in:

A

NAATs (PCR)

96
Q

Modified PVA contain:

A

Zinc sulfate or copper sulfate

97
Q

Modified PVA can be used in:

A

Permanent Staining (PS)

98
Q
A