Lab II Exam: Parasitology Flashcards
Which genera of parasites can be detected and identified by examination of a PBS?
Plasmodium Trypanosoma Leishmania Loa Brugia Wucheritia
What are the four components of the procedure for the lab exam of a stool specimen for ova and parasites?
macroscopic exam
direct microscopic exam
concentration procedure
permanent stain smear
Name the two procedures commonly used for the concentration of a stool specimen and give the principle of each procedure.
formalin; ethyl acetate - sedimentation
ZnSO4 - flotation
Why is it useful to perform the direct examination of a stool specimen using both saline and iodine?
saline; to see motile trophs and larvae and to observe helminth ova
iodine; darkens the nuclei, to observe cyst of protozoa
Name several artifacts that can be found in ova and parasite preparations.
WBC RBC yeast pollen grain fibers charcot-leyden cyrtstals
What is a scotch tape preparation and for what organism it is used?
press tape against anal opening prior to bed or after waking; ova stick to the tape
used for microscopic exam of pinworms
How soon after collection should a semi-solid or liquid stool be examined?
A formed stool?
within 30 minutes of passage
same day/direct smear
If a formed stool cannot be examined on the day of collection what steps should be taken?
add preservative and refrigerate
What stage of a protozoan (cyst or troph) is most likely to be seen in liquid stool?
Formed stool?
troph
cyst
What fixative should be used with a liquid stool?
Formed stools?
PVA-polyvinyl alcohol
10% formalin - solution of formaldehyde
What fixative should be used with a liquid stool?
Formed stools?
PVA-polyvinyl alcohol
10% formalin - solution of formaldehyde
What type of container is best to use for the collection and transporting of a stool specimen?
one that is clean and dry
not waxy; can give false + on AFB
Name several specimens other than stools that might be examined for ova and parasites.
CSF blood urine sputum duodenum aspirates perianal(scotch tape)
What are Charcot-Leyden crystals?
What is their significance?
What are they composed of?
spindle shaped structures
none; artifacts
granules of eos
Name several species of protozoa that have “emerged” as significant pathogens in recent years due to the spread of AIDS.
Toxoplasma
Cryptosporidium
Pneumocytosis carinii
