Two methods are available for the staining of protozoa: 1) Iron-haematoxylin stain 2) Wheatley’s tnchome stain. The iron haematoxylin staining is the older method and is more difficult.
1. Iron-haematoxylin stain
1) Fecal smear on a slide is fixed in Schaudinn’s solution for 15 minutes. 2) It is then immersed successively for 2 to 5 minutes in 70% alcohol, 70% alcohol containing trace of iodine, 70% alcohol and 50% alcohol. 3) It is then washed in water for 5 to 10 minutes and immersed in 2% aqueous ferric ammonium sulphate solution for 5 to 10 minutes. 4) It is then washed in water for 3 to 5 minutes and stained with 0.5% aqueous haematoxylin for 5 to 15 minutes. 5) It is washed for 2 to 5 minutes and differentiated in saturated aqueous solution of picric acid for 10 to 15 minutes. 6) It is then washed for 10 to 15 minutes and dehydrated by passing through increasing strength of alcohol. 7) The slide is then cleared in toluene or lolls and mounted.
2. Wheatley trachoma stain
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It is a simpler and quicker method.The smear is fixed in Schaudinn’s solution. Later, it is taken successively in different concentrations of alcohol. It is stained with trachoma stain for 5 to 10 minutes. Later it is differentiated in acid alcohol for 2 to 3 seconds, dehydrated, cleared and mounted.