MLT069: PARASITOLOGY LABORATORY
Ques 1. Illustrates the physical and chemical examination of stool samples for the
presence of protozoal and helminth infections.
Ans 1.
➢ Sample
1. Can take a random stool sample.
a. More than 2 grams of the stool is needed, ideally 2 to 5 grams.
2. To rule out worm infestation, three consecutive stools are tested.
a. Collect three stools in the span of 10 days.
b. Two samples on alternate days.
i. The hospitalized patient can take a stool sample every day.
ii. Multiple samples are needed to rule out the parasitic infestation.
c. One sample after purgation.
3. Collect the sample in a clean, water-tight dry urine free container with a tight lid.
4. In the case of Infants, collect from the diaper.
5. Or cellophane tape method:
a. This is also known as Scotch tape preparation.
b. This is the best method in infants and children to diagnose pinworms
(Enterobius vermicularis).
c. The female at night, when the child is resting, comes out of the rectum and
lays eggs in the perianal area.
d. Put the tape at night and collect the tape in the morning.
e. Procedure:
i. Take 10 cm of the transparent adhesive tape.
ii. Fold it on the tongue depressor with the adhesive side out.
iii. Now press the adhesive side of the tape over the perianal area and
cover the maximum area. Should apply this tape at night.
iv. In the morning, remove the tape and put the adhesive side on the slide.
v. See under the microscope.
➢ Method to prepare the stool smears:
Saline and iodine Direct wet preparations:
Saline wet preparation:
1. Take one drop of 0.85% saline.
2. Take a small amount of stool and mix well.
3. The smear should be thin so that you can see the newsprint under the slide.
4. Put cover glass and see under the microscope 100x and 400x objective.
a. This is best to see helminth eggs, larva, and trophozoites.
1
, Iodine wet preparation:
This is also called wet preparation.
I. Iodine solution consists of:
A. Potassium iodide (KI) = 10 grams
B. Iodine powder crystals = 5 grams
C. Distilled water = 100 ml
D. Procedure to make Lugol’s iodine solution:
1. Dissolve KI in D.water.
2. Slowly add iodine crystals.
3. Shake the solution gently until they dissolve.
4. Filter the solution before use, and this is the stock solution.
5. Dilute the stock solution 1:5 with D. water. Make this working solution
before use.
A. Take a drop of Lugol’s iodine solution.
B. Take a small amount of stool and mix it well.
C. Make a thin smear.
D. Put the cover glass on it and gently press it to get an evenly thin smear.
E. See under 100x and 400x objective lenses.
a. Too weak iodine solution; in that case, organisms will not stain properly.
b. Too strong iodine solution will clump the stool.
➢ Concentration method
The main aim of the concentration method is to remove the debris. Also, when the parasite is
low in number.
2
Ques 1. Illustrates the physical and chemical examination of stool samples for the
presence of protozoal and helminth infections.
Ans 1.
➢ Sample
1. Can take a random stool sample.
a. More than 2 grams of the stool is needed, ideally 2 to 5 grams.
2. To rule out worm infestation, three consecutive stools are tested.
a. Collect three stools in the span of 10 days.
b. Two samples on alternate days.
i. The hospitalized patient can take a stool sample every day.
ii. Multiple samples are needed to rule out the parasitic infestation.
c. One sample after purgation.
3. Collect the sample in a clean, water-tight dry urine free container with a tight lid.
4. In the case of Infants, collect from the diaper.
5. Or cellophane tape method:
a. This is also known as Scotch tape preparation.
b. This is the best method in infants and children to diagnose pinworms
(Enterobius vermicularis).
c. The female at night, when the child is resting, comes out of the rectum and
lays eggs in the perianal area.
d. Put the tape at night and collect the tape in the morning.
e. Procedure:
i. Take 10 cm of the transparent adhesive tape.
ii. Fold it on the tongue depressor with the adhesive side out.
iii. Now press the adhesive side of the tape over the perianal area and
cover the maximum area. Should apply this tape at night.
iv. In the morning, remove the tape and put the adhesive side on the slide.
v. See under the microscope.
➢ Method to prepare the stool smears:
Saline and iodine Direct wet preparations:
Saline wet preparation:
1. Take one drop of 0.85% saline.
2. Take a small amount of stool and mix well.
3. The smear should be thin so that you can see the newsprint under the slide.
4. Put cover glass and see under the microscope 100x and 400x objective.
a. This is best to see helminth eggs, larva, and trophozoites.
1
, Iodine wet preparation:
This is also called wet preparation.
I. Iodine solution consists of:
A. Potassium iodide (KI) = 10 grams
B. Iodine powder crystals = 5 grams
C. Distilled water = 100 ml
D. Procedure to make Lugol’s iodine solution:
1. Dissolve KI in D.water.
2. Slowly add iodine crystals.
3. Shake the solution gently until they dissolve.
4. Filter the solution before use, and this is the stock solution.
5. Dilute the stock solution 1:5 with D. water. Make this working solution
before use.
A. Take a drop of Lugol’s iodine solution.
B. Take a small amount of stool and mix it well.
C. Make a thin smear.
D. Put the cover glass on it and gently press it to get an evenly thin smear.
E. See under 100x and 400x objective lenses.
a. Too weak iodine solution; in that case, organisms will not stain properly.
b. Too strong iodine solution will clump the stool.
➢ Concentration method
The main aim of the concentration method is to remove the debris. Also, when the parasite is
low in number.
2
