Development of a chromogenic in situ hybridization for Giardia duodenalis and its application in canine, feline, and porcine intestinal tissues samples.

In the present study, a chromogenic in situ hybridization for the identification of Giardia duodenalis in paraffin-embedded tissue samples was developed. The sensitivity and specificity of the probe was validated by testing it on cultured reference samples of different assemblages of G. duodenalis as well as culture and tissue samples containing other protozoa and infectious agents. The probe gave a positive reaction with the Giardia samples and a negative reaction with all other samples. Further, the probe was used for screening of histological slides of intestine from different animal species (99 canine samples, 85 feline samples, and 202 porcine samples) for the presence of G. duodenalis trophozoites. With this assay, the parasites were detected in samples from 8 dogs (8.08%), 6 cats (7.06%), and zero pigs. The results clearly indicate that the described method is useful for detection of Giardia trophozoites in routinely processed intestinal tissue of different animal species.