Detection of Cryptosporidium parvum Using the Kinyoun Acid-Fast Stain

As infection with Cryptosporidium parvum becomes increasingly recognized as a cause of outbreaks of foal diarrhea, a rapid method of oocyst detection in equine feces that can be done easily in the practice setting is desirable. Protozoal identification techniques that have been described include the evaluation of stained fecal smears or preparations of floated feces, using both light and phase-contrast microscopy. Immunologic methods include immunofluorescent assays (IFA’s) and enzyme-linked immunosorbent assay techniques. Commercial veterinary diagnostic laboratories most commonly use acid-fast staining or IFA methods. Poor sensitivity and specificity have been associated with the acid-fast staining of fecal specimens in human studies, and these data have been extrapolated to equine reports. Because IFA procedures have been reported to be ten times more sensitive than acid-fast techniques, many veterinarians routinely submit fecal samples for evaluation to commercial laboratories for IFA testing. The submission of fecal samples to commercial laboratories can be labor intensive and result in either delayed results or even a failure to submit samples for evaluation. A reliable, low cost, and simple method that can be done in the practice setting is necessary to enable the practitioner to arrive quickly at a diagnosis and prevent potential complications. Recent evidence from our laboratory indicates that the Kinyoun Acid-Fast Stain will perform as well or better than an IFA in this setting.