Diagnostic Techniques Flashcards
What is a perfect gold standard of diagnosis?
test is 100% specific and sensitive
Is the perfect gold standard of diagnosis often achieved?
no
What is a gold standard?
best available test: sensitivity & specificity are well defined but less than gold standard
What steps are involved in a direct wet smear?
- ~2mg feces w/ saline are put on a slide 2. observe under microscope
Why is a direct wet smear not the preferred method of fecal sampling?
false negatives bc # of eggs in feces is too low
Describe the formalin-ethyl acetate sedimentation concentration method.
- mix 4g of feces with formalin 2. strain through gauze 3. mix with saline 4. centrifuge & discard supernatant 5. add more fomalin & ethyl acetate 6. centrifuge & discard supernatant 7. sediment - bottom layer with parasite eggs 8. put small amounts on slide and look under microscope
How are urine samples tested for parasites?
sample is collected in clean container -> centrifuge -> examine sediment
How would a blood test be done?
sample -> smear -> look under microscope
In which class is Toxocara canis classified?
Chromadorea
What is the normal DH of Toxocara canis?
dog
How do dogs become infected by Toxocara canis?
- ingest eggs 2. if pregnant dog becomes infected then larva crosses fetus 3. if lactating dog becomes infected -> transmammary 4. ingest prey with larvae
How does a human become an accidental host in Toxocara canis?
ingests eggs
What are visceral larva migrans and ocular larve migrans?
visceral larva migrans - larva that migrate through tissues & do not complete development (developmental arrest) just extended random wandering through body vs. ocular larva migrans - inflammation, scarring, blindness
What are the symptoms of Toxocara canis infection?
fever, cough, abdominal pain, vision problems
How can an infect be diagnosed and treated?
diagnosed by ELISA & treated by mebendazole and albendazole