parasitology lab exam

Question 1

which genera of parasites can be detected and identified by examination of a peripheral blood smear?

Answer 1

plasmodium
trypanosoma
loa
brugid

Question 2

what are the four components of the procedure for the laboratory examination of a stool specimen for ova and parasites?

Answer 2

macro-exam direct

micro exam- concentration, procedure, permanent stain smear

Question 3

name the two procedures commonly used for the concentration of a stool specimen and give the principle of each procedure

Answer 3

formelin ethyl acetate- sedimentation

zinc sulfate- flotation

Question 4

why is it useful to perform the direct examination of a stool specimen using both saline and iodine?

Answer 4

S- motile trophs/ larvae- moving- observing helminth ova

I- observes cysts of protozoa

Question 5

name several artifacts that can be found in ova and parasite preparations

Answer 5

WBC
RBC
yeast
epithelial cells
plant/meat fibers
charcot-leyden crystals

Question 6

what is a scotch tape preparation and for what organism is it used?

Answer 6

a piece of tape or out patient device pressed over the anal opening at night (right after going to bed or right before getting up in the morning) the ova stick then examine under microscope for pinworm eggs

Question 7

how soon after collection should a semi-solid or liquid stool be examined?

Answer 7

within 30 minutes of passage

Question 8

how soon after collection should a formed stool be examined?

Answer 8

within the same day

Question 9

if a formed stool cannot be examined on the day of collection, what steps should be taken?

Answer 9

place it in a preservative and refrigerate

Question 10

what stage of a protozoan (cyst or troph) is most likely to be seen in a liquid stool?

Answer 10

troph

Question 11

what stage of protozoan is most likely to be seen in a formed stool?

Answer 11

cyst

Question 12

what fixative should be used with a liquid stool?

Answer 12

PVA- polyvynal alcohol

Question 13

what type of container is best to use for the collection and transporting of a stool specimen?

Answer 13

clean and dry doesn’t need to be sterile

Question 14

what fixative should be used with a formed stool?

Answer 14

10% formelin

Question 15

name several specimens other than stools that might be examined for ova and parasites

Answer 15

sputum
blood
urine
CSF
duodenal aspirates
perianal swabs

Question 16

what are Charcot-Leyden crystals?

Answer 16

spindle shaped artifacts

Question 17

what is the significance of the charcot-leyden crystals

Answer 17

E. histolytica

Question 18

what are charcot-leyden crystals thought to be composed of?

Answer 18

eosinophil granules

Question 19

name several species of protozoa that have “emerged” as significant pathogens in recent years due to the spread of AIDS

Answer 19

toxoplasma
Pneumocytitis carinii
cryptococcus

Question 20

REMEMBER TO

Answer 20

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