Parasitology Diagnostics PDF

PARASITOLOGY 3 Parasitology Diagnostics Dr. Cassan Pulaski Learning Objectives: Students will be able to describe the different techniques used to diagnose parasites. Students will be able to determine the appropriate diagnostic test, including the decision process to perform test...

PARASITOLOGY 3 Parasitology Diagnostics Dr. Cassan Pulaski Learning Objectives: Students will be able to describe the different techniques used to diagnose parasites. Students will be able to determine the appropriate diagnostic test, including the decision process to perform tests in-house or to send out to diagnostic laboratory. Students will be able to recognize the importance of proper sample handling methods, including collection, submission, preservation, shipping, etc., and the recognition of the biohazard potential of parasitological samples. Useful Sites! https://parasitology.cvm.ncsu.edu/m_keys/m_keys.html https://youtube.com/playlist?list=PLOfWDvAF1PP0gBVT4I- NSPzchsTOIZdoK&feature=shared https://wcvm.usask.ca/learnaboutparasites/index.php IMAGES: – https://www.veterinaryparasitology.com/ – https://www.ncvetp.org/parasite-image-dataase.html  Parasitology diagnostics fall into 2 categories: Tests based on the (visual) morphological identification of the parasite stage available – e.g., blood, feces, urine, tissue section – e.g., Geima staining, McMasters FEC, sedimentation, histopathology Tests that do not… – e.g., Fecal Antigen, PCR, serology Qualitative vs Quantitative ↓ ↓ presence number VS. calculate) & absences (count eggs FE C (yes vs. no... * frequentlyLarge * frequently small Animal/ Animal Ruminants  GOOD sample = GOOD results Fresh is best! – If not possible, then refrigeration or preservation solution (e.g., formalin, ethanol) Fresh samples have increased risk for infectious agent exposure – Don’t forget about opportunistic collections! e of contamination risks To see e moti Temperature probe: saline direct fecal mount for Giardia Stake care Last drop of blood in the syringe: direct blood mount for microfilariae (heart worms The more the merrier (and more accurate!) – At least 1 gram of feces for flotation – Need to weigh starting volume for quantitative tests When in doubt, CALL YOUR FRIENDLY, NEIGHBORHOOD PARASITOLOGIST!  Looking for parasites in blood -especialtracellular Several parasitic protozoa (e.g. Trypanosoma and Babesia), as well as the first- stage larvae (microfilariae) of some tissue-dwelling nematodes (e.g. D. immitis), can be detected in stained films of peripheral blood – Giemsa most frequently used Clinical Signs: anemia, fever, lethargy, known exposure to ectoparasites Heartworm testing, ID’ing microfilariae don'needt this one but > - DoNEPiriaT – Modified Knott’s test > - Heartworm T Adultsliveia X Dirofilaria immitis vs Acanthocheilonema reconditum routinely Not in Quantitative microfilariae count done NEED: 1ml EDTA blood, 2% formalin, methylene blue practice  Cytauxzoon felis Trypanosoma cruzi Dirofilaria immitis transmitted via ticks Chagas disease Heart Worms · common in wild cats in domestic cats. dangerous Xfecal shortcase min. Looking for parasites in feces CS: diarrhea, weight loss, ill-thrift, COUGHING Should be part of your minimum database! Multiple testing options: – Direct Mount – Flotation with centrifugation – Sedimentation – Baermann technique – McMasters Fecal Egg Count DO NOT USE FECAL LOOPS! Direct fecal mount * MOTILE This is usually used to detect and identify protozoan trophozoites, cysts and oocysts in fresh feces, also some larvae iodineSta ↳  X passive floats miss A LOT - Flotation WITH centrifugation ↳ hard to recover some eggs bic some are heavier (they don't float) If feces are thoroughly mixed with a flotation solution of relatively high specific gravity, filtered, and left to stand the lighter weight eggs, cysts and oocysts will float to the surface of the fecal suspension. They can then be recovered and examined microscopically – Centrifugation of the fecal suspension significantly improves the efficiency of the flotation procedure by bringing more eggs to the surface of the suspension Passive float Eunipworms (sugar solution) SG : 1 25-1.. 8 SG Solution * a higher the will collapse Giardia  Sedimentation & Baermann Sedimentation: used to recover eggs of trematodes, which do not float in & standard flotation techniques more fluke Commo my eggs – Fasciolahepatica, Cliver fluke) * for * used cattle Macracanthorhynchus sp. S Baermann technique: used to recover ↓ live nematode larvae from fresh feces – Dictyocaulus viviparus, (lung worms must be Aelurostrongylus abstrusus, live for larvae Angiostrongylus vasorum to more down Quantitative Fecal Diagnostics * McMasters -> ideal for horsesa ruminants Dilution egg counts = more accurate when EPGs are high – Known fecal volume, known flotation media, known chamber capacity Greatest utility in estimating levels of strongyle infections in ruminants and horses – Not if they are infected, rather what level of infection Different protocols, chambers have different minimum detection limits – 4gm : 26mL McMasters = 25 EPG minimum – 2gm : 28mL McMasters = 50 EPG minimum – 2gm : 18mL miniFLOTAC = 5 EPG minimum Why Quantify? Identifying your high shedders / contamination risks Selective deworming Conly select high shedders to de-worm) Determining treatment efficacy * Note: Capacity to tolerate and resist parasites varies among animals in a herd – 20-30% of animals have 80% of the parasites! shedders * frequently the highest are subclinical Other samples / tests: Urine – Ova usually seen in urine sediment – Dioctophyme renale Igiant kidney worm) – Similar process for BAL/TTW recovery (ova, larvae) Skin Biopsy / Skin Snip – Leave tissue in saline overnight – Microfilariae not in blood (Onchocerca sp.) Others: – Smash prep of proglottids (if see tape worms in feces – Tape test for pinworms Non-morphological diagnostics Accurate morphological diagnostics are reader dependent… – Automated counters, AI-powered image analyzers Other options exist – Antigen Detection of parasite antigens in blood/serum or feces (coproantigen) e.g., Giardia SNAP, hooks/rounds/whips/flea tapeworm/coccidia Need to interpret results carefully… – Serology Like antigen, detection in the blood of either parasite antigen or of antibodies produced by the host to parasite antigen – PCR Detection of various genetic markers in different parasites has enabled species identification of parasite stages found in feces, blood, or tissues Looking for ectoparasites Skin Scrape – Used to recover small ectoparasites, particularly the various species of tiny mites associated with mange – e.g. Demodex Swab & Slide – e.g. Otodectes lear mites) Skin and hair coat examination – Flea comb – Visual inspection – Vacuum… Egg / Oocyst Comparison - CANINE Egg / Oocyst Comparison - FELINE Egg / Oocyst Comparison - EQUINE Egg / Oocyst Comparison - RUMINANT Questions? Quiz 1 & 2 due Saturday