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Parasitology > Lecture 3: Diagnostic Techniques > Flashcards

Lecture 3: Diagnostic Techniques Flashcards

1
Q

Possible diagnostic samples (6)

A

Feces
Vomit
Blood
Urine
Skin scrapes
Formalin fixed tissue samples

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2
Q

Qualitative exam techniques: feces (5)

A

Direct visualization
Direct smear
Concentration techniques = Fecal flotation, Fecal sedimentation, Baermann

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3
Q

When to use direct visualization of endoparasites (and examples of parasites that can be seen)

A

If adult endoparasites are expelled in feces or vomitus
Toxocara canis roundworms, stomach worm, tapeworm proglottids

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4
Q

Direct fecal smear: how to perform, when not useful, when most useful

A

Drop of saline + small amount of feces + coverslip
NO = most GI parasites
YES = observe motility of Protozoal parasites that have motile stages

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5
Q

Fecal flotation: requirements and why this is important

A

Flotation solution must have higher/heavier specific gravity than most common parasites eggs/cysts
Higher specific gravity = eggs/cysts will float to top of solution

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6
Q

Fecal flotation: how to perform

A

Flotation solution = zinc sulfate or sucrose
Mix fecal debris in flotation solution then place coverslip over tube, eggs/cysts float and attach to coverslip

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7
Q

When to use fecal sedimentation (including species)

A

Detect eggs/cysts that are too heavy or delicate to concentrate by fecal flotation
Non nematode eggs = trematode, acantocephalan
Protozoal cysts = amoebae, ciliates, giardia species

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8
Q

Is fecal sedimentation sensitive for nematode eggs or coccidian oocysts?

A

No

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9
Q

When and for what species is Baermann technique useful (and what does this technique rely on)

A

Recovering nematode larvae from samples
Some lung worms and strongyloides species
Relies on motility

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10
Q

Is Baermann technique recommended as a primary diagnostic test for evaluation of parasites in feces

A

No

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11
Q

Baermann technique: main components

A

Diagnostic sample covered in water
Isolate motile larvae through straining

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12
Q

2 examples of when Baermann is not useful and instead flotation is preferred

A

Lethargic larvae
Or if larvae are not produced

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13
Q

Direct smear: when to use, cons

A

Protozoal GI infection with motile stages
Not very sensitive —> don’t use as primary diagnostic tool

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14
Q

Fecal flotation: when to use, cons

A

Nematode infection that produces eggs/cysts
If eggs/cysts are too heavy to float

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15
Q

Fecal sedimentation: when to use, cons

A

Infections with trematodes or acanthocephalans; amoebae, ciliates, giardia species
Not sensitive for nematode eggs or coccidian oocysts (cryptosporidium)

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16
Q

Baermann: when to use, cons

A

If Motile larvae present in feces (lung worms, strongyloides)
Only useful for isolating motile larval stages

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17
Q

Other Qualitative exam techniques (3)

A

Immunoassays
PCR
Culture of eggs or larvae

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18
Q

Immunoassays: when to use, what is detected specifically

A

GI protozoal parasites = giardia, cryptosporidium
Endoparasites antigens in feces

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19
Q

PCR: what is detected, when to use, variation

A

Endoparasite DNA in feces
Giardia and cryptosporidium
Can be qualitative or quantitative (real time)

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20
Q

Culture of eggs/larvae: target, when to use

A

Morphological differences in Eggs of nematode species
L3
Strongyles in large animals

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21
Q

Quantitative exam techniques (2)

A

Dilution egg counts = Cornell McMaster
Concentration egg count

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22
Q

When are quantitative exam methods used over qualitative methods

A

Better understand level of burden
Large animals always have low levels of egg shedding unless actively being treated

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23
Q

What parasites are targeted for quantitative exam methods

A

Trichostrongyle/strongyles in ruminants and horses

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24
Q

Cornell McMaster dilution egg counting technique: goal, requires what equipment, what does it provide

A

Quantify eggs within diluted fecal sample that is further diluted 1:1 in fecal flotation solution
Specialized microscope chamber slide
Estimate of eggs/gram of feces

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25
Q

Cornell mcmaster dilution egg counting technique: why dilute with flotation solution (2)

A

Decrease number of eggs you must count = enhance accuracy
Allow eggs to float to top of chamber = bringing them to same microscope field, floating above heavier fecal debris

26
Q

When to use concentration egg count vs Cornell McMaster

A

If you suspect low levels of infection and don’t want to dilute sample

27
Q

Concentration egg count: definition (combo of what?), end up with

A

Combo of cornell-McMaster and fecal flotation
Minimum estimate of eggs/gram of feces

28
Q

Types/classifications of eggs (4)

A

Nematode
Trematode
Cestode
Protozoan cysts and oocysts

29
Q

4 types of nematode eggs

A

Ascaridoid
Strongyle type
Trichinelloid/trichuroid
Oxyurid

30
Q

Ascaridoid eggs aka

A

Roundworm eggs

31
Q

Ascaridoid eggs: general characteristics (3)

A

Light brown to brown
Round to oval
Thick wall

32
Q

Canine roundworm: genus and species, type of egg

A

Toxocara canis
Ascaridoid

33
Q

4 main Ascaridoid eggs

A

Toxocara species/canine roundworm
B. Procyonis/Racoon roundworm
Parascaris equorum
Ascaris suum

34
Q

Strongyle type eggs: general characteristics (3)

A

Elongated oval, thin wall
Clear/colorless
Embryonated (spheres pushed together)

35
Q

Examples of Strongyle type eggs (3)

A

Ancylostoma
Strongylus
Haemonchus contortus

36
Q

Oxyurid eggs aka

A

Pinworms

37
Q

Oxyurid eggs: general characteristics (2)

A

Colorless shell
Small operculum/cap on one end

38
Q

Is there a public health concern if horse has pinworms and why

A

No, not transmitted between species

39
Q

Trichinelloid/trichuroid eggs aka

A

Whipworms

40
Q

Trichinelloid/trichuroid eggs: general characteristics (3)

A

Bipolar plugs/bioperculated
Elongate to barrel shaped
Smooth thick wall

41
Q

What kind of test would be best to identify Trichinelloid eggs

A

Fecal flotation

42
Q

Capilllarids look like what kind of worms

A

Whipworms

43
Q

Trematode eggs: general characteristics (2)

A

Brown egg
With operculum

44
Q

Best test to identify trematode eggs and why

A

Fecal sedimentation
Heavy eggs

45
Q

Cestode eggs: general characteristics (3)

A

Embryonated
6 hooked onto sphere inside thick, striated shell

46
Q

Protistan cycsts and oocysts: general characteristic

A

Smaller than most eggs

47
Q

2 main genera of protistan cysts

A

Entamoeba
Giardia

48
Q

3 main genera of protistan oocysts

A

Isospora
Eimeria
Cryptosporidium

49
Q

ID techniques for blood parasites (3)

A

Direct blood smear
Immunoassays for canine heart worm Ag/Ab
Microfilaria concentration techniques = modified knott’s, millipore filter test

50
Q

Direct blood smear: how to do, what is identified

A

Drop of whole blood on slide —> create smear —> dry, fix, stain
Circulating Microfilariae, Protozoa, rickettsia (bacteria)

51
Q

Immunoassays (blood parasite): used to detect

A

Ag or Ab
Dirofilaria immitis

52
Q

Of the Microfilaria concentration techniques, which is preferred

A

Modified knott’s

53
Q

2 Microfilaria recognized in blood of dogs in North America

A

D. Immitis
Acanthochilonema reconditum

54
Q

If animal is positive for D. Immitis on immunoassay, what is next step

A

Perform concentration test to visualize Microfilaria

55
Q

Modified knott’s/millipore filter test: why/how used, when used, concern about using test

A

Concentrate/filter blood to increase likelihood Microfilaria will be visualized
Lyses RBCs
Done after positive immunoassay
False negatives —> Microfilaria not present in all HW infected dogs

56
Q

Techniques for detecting ectoparasites (4)

A

Direct visualization/ID
Skin scraping
Cellophane tape prep
Skin histopathology

57
Q

Direct visualization: how/when to use

A

Use external traits (ornamentation, mouth parts)
Ticks, lice, mites

58
Q

Skin scraping: when to use, how to do, what follows to diagnose

A

If suspect mite infestation (demodex, scabies)
Have to scrape deeply because mites embedded in skin/hair follicles
Dx with skin histopathology

59
Q

Cellophane prep: when to use

A

Trap/catch mites or lice that are close to surface

60
Q

Histopathology usually done when

A

Post Mortem

Parasitology (10 decks)

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