Examination of faeces for parasites Medical Parasitology Examination of faeces for parasites

STOOL EXAMINATION Concentration techniques Increase relative number of parasites for scanty infections. Reduce background fecal debris. Floatation Sedimentation Non Operculated eggs Trematodes ( Schistosoma.) Cestode Nematode (Hookworms) Cysts Heavy eggs (Ascaris egg) Operculated eggs (Trematodes) Larvae (Strong stercolaris.) Cysts

2. Formol ether sedimentation 1. Saline sedimentation

1. Saline sedimentation Emulsify part of the faeces in distilled water or saline. Strain through gauze. Allow to sediment. Decant the supernatant fluid. Repeat washing and sedimentation until the supernatant becomes clear. Microscopically examine the sediment for parasites.

Saline sedimentation Mesh wire gauze Saline Emulsify Conical flask stool Sediment

2. Formol Ether sedimentation Add 10 ml of 10% formalin to the previous sediment. Mix and allow to stand for 10 minutes. Add 3 ml of ether. Centrifuge. Four layers will form: Ether at the top. Plug of debris. Formalin. Sediment. Decant the supernatant and microscopically examine the sediment.

Formol Ether Sedimentation debris 10% Formalin formalin stool Sediment Thorough mixing Conical flask centrif. tube Ether adsorbs fecal debris & floats. Formalin fixes & preserves the specimen.

2. Zinc sulphate floatation 1. Saturated NaCl floatation

1. Saturated NaCl floatation Part of faeces is emulsified in saturated salt solution. Strained in Erlenmyer flask. The flask is completed to its top with salt solution without overflowing. The flask is covered with a slide so as to contact the surface of the solution. After 20 minutes the slide is turned over, covered and microscopically examined.

Slide is turned over, covered and microscopically examined.

2. Zinc sulphate floatation Part of stool is washed and sedimented by centrifuge. The supernatant fluid is decanted and replaced by 33% ZnSO4. Centrifuge. The top fluid is microscopically examined.

Decant the supernatant Centrifuge Add ZnSO4