Laboratory: Intro to Parasitology

Question 1

The most commonly submitted for parasite examination

Answer 1

Stool

Question 2

Most common procedure performed in area of parasitology

Answer 2

Examination of a stool specimen for ova and parasites (O&P)

Question 3

Four Phases of Sample Preparation

Answer 3

Collection
Handling
Preservation
Transport

Question 4

Fecal specimens should be collected in

Answer 4

Clean, wide-mouthed/watertight containers with tight-fitting lid, winged cardboard box (1/2 print) or matchbox

Question 5

Urine should not be allowed to contaminate the stool specimen

Answer 5

True

Question 6

Typical stool collection protocol consists of 3 specimens:

Answer 6

One specimen collected every other day or a total of 3 days
collected in 10 days except in cases of amoebiasis (up to six specimens in 14 days)

Question 7

Certain substances and medications also impede detection of intestinal protozoa

Answer 7

Mineral oil
Bismuth
Antibiotics
Antimalarial agents
Non-absorbable antidiarrheal preparations

Question 8

Stool samples from patients whose therapy includes barium, bismuth or mineral oil should be collected

Answer 8

Prior to therapy or not until 5-7 days after the completion of therapy (5-10 days for barium)

Question 9

Collection of specimens from patients who have taken
antibiotics or antimalarial medications should be delayed for

Answer 9

2 weeks following therapy

Question 10

Patients who have been treated for protozoan infections are typically checked

Answer 10

3-4 weeks after therapy

Question 11

A patient treated for helminth infection may be checked

Answer 11

1- to 2-week post-therapy

Question 12

A patient checks for Taenia may be delayed for

Answer 12

5-6 weeks post therapy

Question 13

Routine stool examination requires a

Answer 13

Thumb-sized/marble stool of formed stool
5-6 tablespoons (10 mL) of watery/diarrheic stool

Question 14

The specimen container should be labeled with

Answer 14

Patient’s name
Identification number
Physician’s name
Date and time of sample collection

Question 15

Liquid specimen should be examined within

Answer 15

30 minutes of passage

Question 16

Semi-formed specimens should be examined within

Answer 16

1 hour of passage

Question 17

Formed stool specimens are not likely to contain trophozoites

Answer 17

True

Question 18

Formed stool specimens are not likely to contain trophozoites; therefore, they can be held for

Answer 18

24 hours following collection

Question 19

Liquid specimen commonly contains

Answer 19

Protozoan trophozoites

Question 20

Formed specimen commonly contains

Answer 20

Cysts

Question 21

Any consistency may contain

Answer 21

Helminth eggs
Larvae

Question 22

If a number of specimens are received at the same time

Answer 22

Pick out the liquid/watery stools
and/or those with mucus/blood because protozoans will be destroyed rapidly

Question 23

Substances that preserve the morphology of protozoa and prevent further development of certain helminth eggs and larvae

Answer 23

Fixatives

Question 24

The ratio of fixative to stool

Answer 24

3 parts fixative to 1-part stool (3:1)

Question 25

The specimen must be fixed in the preservative for at least

Answer 25

30 minutes before processing begins

Question 26

Temporary storage of fecal samples in a refrigerator temperature

Answer 26

4-8 degrees Celsius

Question 27

An aqueous solution of formaldehyde, about 37-40% weight in volume

Answer 27

Formalin

Question 28

Recommended concentration of formalin for preservation of protozoan cyst (trophozoites are destroyed)

Answer 28

5%

Question 29

Recommended concentration of formalin for helminth eggs and larvae

Answer 29

10%

Question 30

Comprised of a plastic powder that acts as an adhesive for the stool specimen when preparing slides for staining

Answer 30

Polyvinyl Alcohol

Question 31

Polyvinyl alcohol is most often combined with

Answer 31

Schaudinn’s solution, which usually contains zinc sulfate, copper sulfate or mercuric chloride as a base

Question 32

Two-Vial System

Answer 32

Formalin vial for the concentration technique (pink or red)

PVA vial for the stained slide (blue)

Question 33

Alternative to mercury-based PVA that uses substitute compounds containing copper sulfate

Answer 33

Modified PVA

Question 34

ECO-FIX

Answer 34

Ecofriendly fixative (PVA)

Question 35

Universal fixative, ecofriendly, contains no formalin, no PVA and no mercury

Answer 35

TOTAL-FIX

Question 36

A combination of preservative and stain for fecal specimens, usually used in field surveys

Answer 36

Merthiolate-Iodine-Formaldehyde

Question 37

Used to preserve fresh stool/fresh fecal specimen in
preparation for staining the stool smear; considered as the “Gold Standard”

Answer 37

Schaudinn’s Solution

Question 38

Alternate to Schaudinn’s; contains 10% formalin as
a fixative plus sodium acetate which acts as a buffer

Answer 38

Sodium-Acetate-Formaldehyde

Question 39

The specimen should be placed into

Answer 39

Zip lock plastic bag for transport

Question 40

10% Formalin (for wet mount)

Answer 40

1-part stool
3 parts formalin
Place in vial, crush stool thoroughly; preserves
specimen indefinitely if bottle is closed

Question 41

MIF (for wet mount)

Answer 41

4.7 mL of MIF
0.3 mL of Lugol’s iodine in a vial bottle (just before dispatching)
Add 2 mL of stool, crush with a glass rod/stick; preserves specimen definitely

Question 42

PVA (for permanent staining)

Answer 42

30 mL of PVA or ¾ in a bottle vial
Enough fresh stool to fill the container
Break stool with stick and cover; preserves all
forms of parasites indefinitely