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Parasitology > Lecture 3: Diagnostic Techniques > Flashcards

Lecture 3: Diagnostic Techniques Flashcards

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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
Cornell mcmaster dilution egg counting technique: why dilute with flotation solution (2)
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
When to use concentration egg count vs Cornell McMaster
If you suspect low levels of infection and don’t want to dilute sample
27
Concentration egg count: definition (combo of what?), end up with
Combo of cornell-McMaster and fecal flotation Minimum estimate of eggs/gram of feces
28
Types/classifications of eggs (4)
Nematode Trematode Cestode Protozoan cysts and oocysts
29
4 types of nematode eggs
Ascaridoid Strongyle type Trichinelloid/trichuroid Oxyurid
30
Ascaridoid eggs aka
Roundworm eggs
31
Ascaridoid eggs: general characteristics (3)
Light brown to brown Round to oval Thick wall
32
Canine roundworm: genus and species, type of egg
Toxocara canis Ascaridoid
33
4 main Ascaridoid eggs
Toxocara species/canine roundworm B. Procyonis/Racoon roundworm Parascaris equorum Ascaris suum
34
Strongyle type eggs: general characteristics (3)
Elongated oval, thin wall Clear/colorless Embryonated (spheres pushed together)
35
Examples of Strongyle type eggs (3)
Ancylostoma Strongylus Haemonchus contortus
36
Oxyurid eggs aka
Pinworms
37
Oxyurid eggs: general characteristics (2)
Colorless shell Small operculum/cap on one end
38
Is there a public health concern if horse has pinworms and why
No, not transmitted between species
39
Trichinelloid/trichuroid eggs aka
Whipworms
40
Trichinelloid/trichuroid eggs: general characteristics (3)
Bipolar plugs/bioperculated Elongate to barrel shaped Smooth thick wall
41
What kind of test would be best to identify Trichinelloid eggs
Fecal flotation
42
Capilllarids look like what kind of worms
Whipworms
43
Trematode eggs: general characteristics (2)
Brown egg With operculum
44
Best test to identify trematode eggs and why
Fecal sedimentation Heavy eggs
45
Cestode eggs: general characteristics (3)
Embryonated 6 hooked onto sphere inside thick, striated shell
46
Protistan cycsts and oocysts: general characteristic
Smaller than most eggs
47
2 main genera of protistan cysts
Entamoeba Giardia
48
3 main genera of protistan oocysts
Isospora Eimeria Cryptosporidium
49
ID techniques for blood parasites (3)
Direct blood smear Immunoassays for canine heart worm Ag/Ab Microfilaria concentration techniques = modified knott’s, millipore filter test
50
Direct blood smear: how to do, what is identified
Drop of whole blood on slide —> create smear —> dry, fix, stain Circulating Microfilariae, Protozoa, rickettsia (bacteria)
51
Immunoassays (blood parasite): used to detect
Ag or Ab Dirofilaria immitis
52
Of the Microfilaria concentration techniques, which is preferred
Modified knott’s
53
2 Microfilaria recognized in blood of dogs in North America
D. Immitis Acanthochilonema reconditum
54
If animal is positive for D. Immitis on immunoassay, what is next step
Perform concentration test to visualize Microfilaria
55
Modified knott’s/millipore filter test: why/how used, when used, concern about using test
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
Techniques for detecting ectoparasites (4)
Direct visualization/ID Skin scraping Cellophane tape prep Skin histopathology
57
Direct visualization: how/when to use
Use external traits (ornamentation, mouth parts) Ticks, lice, mites
58
Skin scraping: when to use, how to do, what follows to diagnose
If suspect mite infestation (demodex, scabies) Have to scrape deeply because mites embedded in skin/hair follicles Dx with skin histopathology
59
Cellophane prep: when to use
Trap/catch mites or lice that are close to surface
60
Histopathology usually done when
Post Mortem

Parasitology (10 decks)

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