Test: Ova and Parasite, Stool for Cyclospora & Isospora (Cystoisospora) Stain 
  Synonym: Parasitology Stain by Modified Acid-Fast 
  Method: Concentration procedure with modified acid-fast stain 
  Availability: Monday, Wednesday, Friday; results within 24 hours (Frequency may be increased during outbreak testing) 
  Specimen: Stool 
  Collection Device: Fresh stool or if transport > 2 hours use Proto-fix vial for preservation and add stool to fill line marked on Proto-fix vial. Seal and shake vigorously. Add bloody or watery portions of stool if present. Stools fixed in 10% formalin are also acceptable. 
  Volume: Walnut size stool specimen or 10 ml of stool in preservative. 
  Storage/Transport: Ambient 
  Unacceptable: Specimens preserved in PVA (polyvinyl alcohol), dry specimens, leaking containers, specimens contaminated with oil, barium, or urine, multiple specimens in 24 hour period, rectal swabs, delayed transport to the laboratory, specimens other than stool. 
  Specimen Stability: Preserved specimen stable for up to 9 months at ambient conditions. 
  Reference Interval: No ova or parasites seen 
  Reportable Disease: Detection of Cryptosporidium species or Cyclospora cayetanensis is reportable. 
  Comments: Proto-fix vials available from Regional Pathology Services.

This test is recommended for the examination of stool for the presence of Cyclospora or Isospora (Cystoisospora) by modified acid-fast stain. Recommended testing for Cryptosporidium is by use of the Giardia/Cryptosporidium Antigen EIA test.

If an unequivocal identification of the parasite cannot be made, the stool specimen can be analyzed using PCR. Fresh stool specimen (to include stool in Cary-Blair transport medium) collected in the absence of preservatives and stored either refrigerated (4°C) or frozen or stool mixed in 2.5% potassium dichromate (1:1 dilution) and refrigerated are the optimal specimens. Alternately, studies have shown that stool preserved in modified PVA (PVA containing zinc and not mercury chloride) can be used for PCR testing, although these samples are NOT acceptable for modified acid-fast staining. When submitting any sample for molecular analysis, also include the original modified acid-fast stain.

Microscopic examination of a concentrated stool specimen following modified acid-fast staining is considered the “gold standard” for the diagnosis of a Cyclospora/Cystoisospora-caused disease. 
  Revised: 8/16/2013