SPECIMEN PROCESSING: Ova and Parasite Examination

Tips and Pitfalls!

A. Fixatives should be mixed well with the specimen; ratio of 1 part specimen to 3 parts fixative is recommended.

B. Centrifugation speed (concentration) is critical for the adequate recovery of organisms. Recommended time/speed is 10 min at 500 Xg; this will allow recovery of all protozoa, including coccidian oocysts and microsporidian spores.

C. The color range of organisms stained with Wheatley's trichrome varies tremendously; different colors do not indicate problems with the stain unless everything (background, organisms) stain uniform pink or red (change reagents, specimen may not have been well preserved).