L4: Diagnostics Flashcards
what types of parasites fall under the Endoparasite category
- Protozoa (unicellular)
- Helminths (multicellular worms)
Ectoparasites are parasites with….
jointed appendages
ticks, mites, lice, fleas, flies/bots
what are the common types of protozoal parasites
- flagellates
- amoeba
- ciliates
- apicomplexans
what are the 3 categories of helminths
- Trematodes (flukes)
- cestodes (tapeworms)
- nematodes (roundworm)
what types of parasites are ectoparasites
- ticks
- fleas
- mites
- lice
- flies/ots
what are the 4 main qualitative techniques for diagnosing endoparasites
- Direct smear
- fecal float
- fecal sedimentation
- baermann
what test should you run if you suspect a protozoal GI infection w/ motile stages
ex: Giardia, Tritrichomonas
Direct smear
what test should you run if you suspect a nematode infection that produces eggs/cysts
fecal float
what test should you run if you suspect an infection with: treamatodes or acanthocephalans, amoebae, ciliates, giaradia
Fecal sedementation
what test should you run if you suspect a motile larvae that would shop up in feces
ex: lung worm or Strongyloides infections
Baermann
what can qualitative tests tell you, what can they not
qualitiate tests help to determine IF an animal is infested
cannot tell to what degree (severity) they are infected
direct visualization is useful for detecting…
adult endoparasites that can be expelled in feces or vomit
ex: tapeworm, Toxocara canis roundworms, Physaloptera stomach worm
when would you utilize a direct fecal smear
when observing the motility of protozoal parasites that have motile stages (giardia, tritrichomonas)
what are the downsides of using direct fecal smear to test for endoparasites
- it is NOT a good tool for detecting most GI parasites
- risk of false negatives
Fecal Float: the floatation solution must have a _________ specific gravity than most common parasite eggs/cysts, this allows the eggs/cysts to FLOAT to the top of the solution
HIGHER/HEAVIER
when would you use fecal sedementation over a fecal float
to detect eggs/cysts that are too heavy or too delicate to concentrate by fecal flotation
what is fecal sedementation most useful for
Non-nematode eggs: Trematode or Acanthocephalan
Certain Protozoal cysts: Amoeba, Ciliates, Giardia
what is the Baermann Technique most useful for
recovering nematode larvae from samples - it relies on their motility
idea is that nematode larvae will wiggle out of the biological material and fall through the water to the area of clamped off tubing
what types of parasites is the Baemann Technique used on
some lung worms and
Strognlyoides
what technique should be used for detecting Aelurostrongylus abstrusus
Baermann
these parasites can all be dected using what test method?
* Crenosoma vulparis
* Angiostrongylus vasorum
* Strongyloides stercoralis
Baermann
why is the Baermann technique not useful for diagnosing canine: Filaroides hirthi, filaroides osleri, Eucoleus
these all have lethargic larvae (non motile)
why is the Baermann technique NOT useful for diagnosing canine Eucoleus aerophilius
lung worm that DOESN’T PRODUCE LARVAE
cons of the direct smear method
- not very sensitive
- do not use as primary diagnositc tool
what are the cons of the fecal flotation technique
some eggs/cysts are too heavy to float (in this case just use fecal sedimentation)
what are the cons of the fecal sedimentation technique
- not very senstitive for nematode eggs or coccidian oocysts
- ex: Cryptosporidium
what is the main con of the Baermann technique
only useful for isolating motile larval stages
immunoassays can be used to diagnose for _________ through the detection of ______ in feces
endoparasites, antigens
PCRs can be used to diagnose for _____ through the detection of parasite _____
endoparasites, DNA
immunoassays are most commonly used for detection of _______ protozoal parasites such as _______ + ________
GI protozoal parasites
Giardia, Cryptosporidium
PCRs are most commonly used for detection of ______ protozoal parasites such as ______ + ________
GI protozoal parasites
Giardia, Cryptosporidium
same as immunoassays
If a PCR test is quantitative the test should be specified as _______
“rt” or “q” PCR = reat time, quantitative
Eggs of different nematode species can look very familiar, morphologic differences found in ________ stage are required for their exact speciation
L3 larvae
trichostrongyles and strongyles are nematodes that commonly infect…
large animals
when diagnosing endoparasites in large animals, why are quantitative tests preferred over qualitative?
LAs usually have low levels of egg shedding therefore the question isn’t if they are infected, but to what degree (burden) they are infected
what is the Cornell-McMaster diltuion technique
quantifies eggs within a diluted fecal sample (1:1) in fecal flotation solution
requires use of specialized microscope chamber slide
provides an estimate of eggs per gram of feces
what are two parasites in ruminants + horses for which a Dilution egg count test would be appropriate
Trichostrongyles
Strongyles
what is the purpose of dilution w/ floatation solution in the Cornell-McMaster egg counting technique
- dilution decreases the # of eggs you have to count (this enhances accuracy)
- floatation solution allows eggs to float to top of chamber
general morphological characteristics of Ascaridoid eggs (roundworm eggs)
- light brown to brown
- round to oval
- thick walls
toxocara canis is…
canine roundworm
Baylisascaris procyonis is…
raccoon roundworm
- neurotropic parasite: cerebral larval migration
general characteristics of Strongyles
- elongated oval shape
- thin wall
- clear
- embryonated
general characteristics of Oxyurid egg (pinworms)
- colorless shell
- small operculum (cap) on one end
general characteristics of Trichuroid Egg (whipworms)
- bipolar plugs (Bioperculated)
- elongate to barrel shaped
- smooth, thick wall
what would be the best way to isolate trichuroid (whipworm) eggs
fecal float
Capillarids are _______ look alikes..how do you tell them apart
whipworm
their bipolar plugs are less prominant, they have a slightly curved appearance and can have pitted/irregular shells
what is the distinguishing trait of trematode eggs
brown egg w/ an operculum
what is the best way to isolate trematode eggs
fecal sedimentation
characteristics of cestode eggs
embryonated, 6 hooked oncosphere inside a thick striated shell (embryophore)
outer shells vary greatly
characteristics of protistan cycsts and oocysts
smaller than most other eggs
what are the main techniques for diagnosig blood parasites
- direct blood smears
- immmunoassays for Dirofilaria immitis antigen/antibody
- microfilaria concentration techniques: modified knott’s, millipore filter test
what types of parasites do direct blood smears identify
microfilariae, protozoa, rickettsiae (Bacteria)
if an animal tests positive for Dirofilaria imminits on an immunoassay, what is the next thing to do
perform a concentration test to VISUALIZE the microfilaria
- modified knott’s (preferred)
- millipore filter test
besides Dirofilaria immitis, what is the other filarid found in the blood of dogs in north america
Acanthochilonema reconditum
narrower and more uniform in width than D.immitis, also has a blunt cephalic end
why might you get false negatives when utilizing microfilaria concentration techniques
microfilariae are not present in all heart-worm infested dogs (and very rarely ever found in cats)
used to concentrate/filter blood to increase the likelihood microfilaria will be visualized. Typically involve lysing RBCs
microfilaria concentration techniques
what are the 4 main techniques to detect ectoparasites
- direct visualization/identification
- skin scraping
- cellophane tape prep
- skin histopathy
what ectoparasites can be identified by direct visualization
- ticks
- lice mite
when is skin scraping usually done?
if a mite infestation is suspected
ex: Demodex, Sarcoptes scabiei
when is cellophane prep used
for trapping/catching mites or lice close to the surface
* can also be used for Oxyuris equi (pinworm) that deposite eggs along the anus
what types of eggs are these?
Ascaridoid eggs
(Roundworm)
- light brown to brown, round / oval and have a thick wall
what type of eggs are these?
Stronglyes
- elongated / oval
- thin wall
- clear
what type of egg is this?
Oxyurid egg
(Pinworms)
- colorless shell and small operculum on one end
what type of egg is this?
Trichuroid egg
(whipworm)
- bipolar plugs, elongated barel shape, smooth thick wall
what egg type is this
Capillarids (trichuroid)
what kind of egg is this?
Trematode eggs
- brown egg w/ operculum
what kind of eggs are these
Cestode
- embryonated, 6 hooked oncosphere present inside a thick, striated shell
