1. Flotation Methods Medical parasitology lab. Faculty of health sciences
Medical Laboratory Sciences Department
Medical parasitology lab.
Flotation Methods

2. Concentration Methods
Sedimentation method
Modified Formal- Ether sedimentation technique
Acid- Ether sedimentation technique
Flotation method
Saturated Salt Solution technique
Sheather’s Sugar Centrifugal Flotation technique
Zinc Sulphate Centrifugal Flotation technique

3. Flotation technique Advantage: Disadvantage:
These method use the high specific gravity of a solution to float the lighter ova and cyst. They can be improved by centrifugation.
Advantage:
Easy to perform .
Disadvantage:
Delay in examination can result in distortion.
Larvae and some fluke eggs do not concentrate.
Frequent checking of specific gravity.

4. Saturated salt solution
Flotation Methods
Saturated salt solution

5. Materials and Method
Boil granular sodium chloride in excess in water to produce a saturated solution which when cooled has a specific gravity of
Half fill a wide- mounted flat bottomed container with the saturated salt solution.
Emulsify 1gm of feces in the solution and strain it to remove the debris from the surface.
Pour the filtrate into meniscus and fill it to the top with saturated salt solution.
Lay a glass slide or large coverslip over the top, avoiding any bubbles being trapped.
Leave for 20 min before quickly inverting the slide.
Scan for ova using the 10x objectives.

6. Saturated Salt solution technique
Advantages:
It is cheap preparation using simple apparatus.
It concentrates nematode ova well.
Disadvantages:
It doesn’t concentrate cysts.

7. Sheather’s Sugar Centrifugal Flotation Technique
Flotation Methods
Sheather’s Sugar Centrifugal Flotation Technique

8. Materials and Method Sheather’s sugar solution:
Table sugar gm
Distilled water ml
Phenol crystal ( melt in hot water bath) gm

9. Procedure: Soften 1gm of feces with water to a soft.
Strain the aqueous suspension through a wire sieve.
Mix 1 part aqueous suspension with 2 part of Sheather's sugar solution.
Pour into a centrifuge tube, centrifugation 1500 rpm for 10 minutes.
Pour the supernatant into a meniscus and add a sufficient solution to bring the meniscus to the top.
Place a coverslip and wait for 10 minutes.
Examine under microscope.

10. Sheather’s Sugar solution technique
Advantages:
Reveals most nematode eggs and protozoan cyst.
Disadvantages:
Flukes eggs and tape worm eggs are not demonstrate well.
Also most nematode larvae are not demonstrate well.

11. Entamoeba histolytica/ dispar
E. histolytica inhabit large intestine and cause amoebic dysentery.
There is two diagnostic stages for E. histolytica/ dispar:
Cyst is regular round measuring measure 10 – 20u in diameter with 4 nuclei, and it’s the infective stage.
Trophozoite is the motile form, measure 15-20u in diameter with large nucleus. (motility by pseudopodia).
Diagnosis:
Stool examination to see cyst stage, or trophozoite stage if the sample is fresh.

13. Entamoeba histolytica/ dispar

14. Entamoeba histolytica/ dispar Trophozoite

15. Thanks