Diagnostic Laboratory Section

SEDIMENTATION TECHNIQUE

Procedure

• Place a lump of faeces (1/2-1 tsp / 5-10 g/ 5-10 faecal pellets (of sheep or goats) in a cup or glass container.
• Add enough tap water and mix thoroughly with a spatula / glass rod until all the faecal material is broken down.
• The mixture is poured through a wire mesh sieve to remove coarse large lumps. Common tea strainer will do. The strained fluid is collected in a bowl. The sieve is rinsed with water and the debris left on the sieve is discarded.
• Transfer the suspension to centrifuge tubes and centrifuge at 2000 rpm for 2 min.
• Discard the supernatant.
• Mix the sediment well and take a small quantity of it and mix it with a drop of water on a clean slide.
• Apply a cover slip and examine under low power objective of the microscope.
• Thickness of the smear should be such that if the slide is placed on a newspaper, you should be able to read the fine print through the smear.
  

Note

• Select a fully representative sample of the stool for concentration.
• Prepare well-mixed suspensions of faeces and water or saline.
• Use the appropriate quantities of materials.
• Use the correct centrifuge speed and time.
• Prepare and examine mounts carefully as described for direct wet mounts.
• Do not discard the tube containing the concentrated material until you have completed your examination. You may need to make another mount.

Parasite stages detected with the sedimentation method

• Eggs of trematodes
• Larvae of lung worms
• Eimeria oocysts