Parasitology paractice 4

College of Health Sciences
Dep. of Medical Laboratories
Parasitology Practice
3rd stage
Lecture 4
Dr.: Shameeran S. Ismael
BVM & S, M.Sc Medical Microbiology(Parasitology),
PhD Molecular Parasitology
Shameeran S. Ismael Parasitolog
Practice.Medical Laboratories, 2020

 A concentration technique is performed
mainly to separate the parasites from fecal
debris.
 The concentration procedure not only
increases the number of parasites in the
sediment but it also unmasks them, making
them more visible by removing organic and
inorganic debris.
II. Concentration Methods

Advantages of concentration method:
 Detect the light infection
 Reduce background fecal debris
 Increase relative number of parasites
 Preserve morphology of parasites
Disadvantages:
 Destroys trophozoite stages.

1. Flotation Method:
• In tape water, worms eggs will sink because their
specific gravity is a little higher than 1. When
fecal samples are suspended in a liquid with
specific gravity higher than that of the eggs and
the water, the eggs will float up to the surface.
Concentration methods includes:

 Operculated eggs as well as schistosoma spp. and
Ascaris eggs are not easily recovered by this method.
 Also trophozoites are killed due to the high specific
gravity

1. Saturated sodium chloride (salt): Mixed 400g of salt
with 1L of hot distal water.
2. Sugar solution (Sheather’s sugar) : 1300 g/L of D.W
3. Saturated sodium Nitrate NaNO3: (400g/ L of
D.W)
4. Saturated Zinc Sulphate ZnSO4: (700g/ L of D.W)
5. Magnesium Sulphate MgSO4: (500g/L of D.W)
Common Flotation or Saturated solution

Advantages:-
 The concentrate is clear of debris
Disadvantages:-
 Delay in examination can result in distortion
 Larvae and some fluke eggs do not concentrate
Advantages and Disadvantages of flotation fecal
method:

1.Mix 3-5 g of fresh feces with little amount of
concentration solution.
2.Dilute then with concentration solution while stirring
vigorously to obtain a homogenous mixture.
3.Solution will be strained through a fine sieve and
residue will be pressed out.
4.Fills test tubes with this solution and carefully put
cover slide on the top of the tube.
Procedure:

5. After 10-30 minutes, the cover slide is gently removed
and put on slide, then examined under microscope.
6. This method is suitable for the majority of nematode
eggs, cestodes and protozoa.

7. Nematodes and cestodes eggs float in a liquid with
a specific gravity between 1.10-1.2 by using sodium
chloride or magnesium sulphate flotation solution.
Trematode eggs which are heavier require a specific
gravity of 1.30-1.35 by using zinc chloride or zinc
sulphate flotation solution.

• Sedimentation, it is primarily used to detect eggs
or cysts that have too high a specific gravity.
When we use water with feces the eggs /or larvea
deposited at button of tubes, because the specific
gravity of eggs/or larvae higher the specific
gravity of water.
Shameeran S. Ismael Parasitology theory.
Vet. Med, 2019
2- Sedimentation Method

Advantages:
 Recovers most ova, cysts and larvae .
 Morphology of most parasites is retained.
Disadvantages:
 Preparation contains debris.
 Some parasites do not concentrate well.
 Liquid faeces do not concentrate well .
Vet. Med, 2019
Advantages and Disadvantages:

1- Mix 1-2g of fecal with 30-60ml of tap water or normal
saline in a cup or beaker.
2- Strain the mixture through a tea strainer into a centrifuge
tube.
3- Centrifuge the sample at 1500 rpm /5 minutes. If a
centrifuge is unavailable, allow the mixture to sit without
disturbed for 20-30 minutes.
Vet. Med, 2019
Procedure:

4-Pour off the liquid in the top of the tube without
disturbed the sediment at the button.
5- Using pipette and transfer a small amount of the top
layer of sediment to a slide. If the drop is too thick,
dilute it with a drop of water.
6- Placed a cover slide to the drop and examine under
the microscope
Vet. Med, 2019

Vet. Med, 2019
1- Obtain about a one to
two gram fecal sample
2-Mix it with water by
stick.
3- Strain the mixture
4-Pour the strained preparation into a
centrifuge tube.

Vet. Med, 2019
6- Centrifuge at 1500 rpm for
5 minutes.
5- Here is the appearance of the
suspension before centrifugation.
7-The appearance of the
suspension after centrifugation.8- Decant the supernatant

Vet. Med, 2019
9- A few drops of the suspension will
remain in the tube over the sediment
pellet
10- Using a pipette remove some of the
sediment from the top layer and place a drop
on a slide for examination.
11-Place a cover slip over the drop
of sediment suspension
12- Examine under microscope.

Vet. Med, 2019
Examples of parasitic stages that might
be seen under the microscope
Entamoeba cysts.
Faciola egg

Vet. Med, 2019
Concentration techniques
Sedimentation Floatation
• Heavy eggs (Ascaris egg)
• Operculated eggs (Trematodes except
Schistosoma)
(Most Trematodes eggs are relatively large
and heavy compared to nematode eggs.)
•Larvae (Strong sterc.)
• Cysts
• Non Operculated eggs of
Trematodes ( S. m.)
• Cestodes
• Nematode
• Cysts

Thanks for attention,,,

Parasitology paractice 4

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