Diagnostic parasitology techniques Flashcards
what does endoparasites break down into? (broad)
protozoa - unicellular
helminths - multicellular worms
what are the key characteristics of ectoparasites?
jointed appendages
what are common protozoal parasites in veterinary medicine?
flagellates, amoeba, ciliates, apicomplexans
what are the common helminth parasites in veterinary medicine?
trematodes (flukes), cestodes (tapeworms), nematodes
what are the common ectoparasites in veterinary medicine?
ticks, mites, lice, fleas, flies/bots
what are the possible diagnostic samples you may encounter?
feces
sputum/vomitus
blood
urine
skin scrapes
formalin-fixed tissues samples -> histopathology
what does a qualitative test tell you?
wether an animal is infected
what does a quantitative test tell you?
tells you the amount affected
what are qualitative tests to diagnose endoparasites for feces?
direct visualization
direct smear
concentration techniques - fecal flotation, fecal sedimentation, baermann, immunoassays, polymerase chain reaction (PCR), culture of eggs or larvae
how do you get a parasitologist to tell you what the parasite it?
save in 70% ethanol and submit to veterinary diagnostic lab
what type of parasites get expelled in the feces or vomitus?
adult endoparasites
how do you prepare a direct fecal smear?
drop of saline + small amount of fecal material + coverslip
what has a risk for false negatives and is not a great tool for detecting most GI parasites?
direct fecal smear
what test is most useful when observing the motility of protozoal parasites that have motile stages?
direct fecal smear
what must the fecal flotation have for the most common parasites eggs/cysts to float?
higher/heavier specific gravity than most common parasites eggs/cysts
what is a good test for nematode eggs?
fecal flotation
what test is used to detect eggs/cysts that are too heavy to concentration by fecal flotation?
fecal sedimentation
what test is most useful for non-nematode eggs and certain protozoal cysts?
fecal sedimentation
what are some non-nematode eggs that fecal sedimentation are useful for?
trematode or acanthocephalan
what are some certain protozoal cysts that fecal sedimentation are useful for?
amoebae, ciliates, Giardia spp.
what is the fecal sedimentation not sensitive for?
nematode eggs or coccidian oocysts
what is the baermann technique useful for?
nematode larvae
How does the Baermann technique recover nematode larvae?
nematode larvae will wiggle out of biological material, cannot swim against gravity and will fall through the water to the area of clamped off tubing
what is the baermann technique useful for identifying?
lung worms and Strongyloides spp.
what is this test called?
Baermann technique
what is this test called?
fecal sedimentation
what test would you do when you suspect a protozoal GI infection that has motile stages?
direct smear
what test would you do when you suspect a nematode infection that produce eggs/cysts?
fecal flotation
what test would you do when you suspect infections with trematodes or acanthocephalans, amoebae, ciliates, Giardia spp.?
Fecal sedimentation
what test would you do when you suspect motile larvae is present in the species (lung worm or Strongyloides spp. infections)?
Baermann
what are the cons of a direct smear?
not very sensitive, don’t use as a primary diagnostic tool
what are the cons of a fecal flotation?
some eggs/cysts are too heavy to float (use fecal sedimentation in this case)
what are the cons of fecal sedimentation?
not very sensitive for nematode eggs or coccidian oocysts (ex. Cryptosporidium spp.)
what are the cons of Baermann test?
only useful for isolating motile larval stages
what is an immunoassay for feces?
detection of parasite antigens in feces
what is a PCR for feces?
detection of parasite DNA, can be quantitative depending on test
what is the immunoassay most commonly used for?
GI protozoal parasites - Giardia & Cryptosporidium
what are PCRs most commonly used for?
GI protozoal parasites - Giardia & Cryptosporidium spp.
Which PCR is qualitative or quantitative?
rt - qualitative
q - quantitative
what does a lower Ct indicate?
higher burden