A comparison of phase contrast microscopy and an immunofluorescence test for the detection of Giardia spp. in faecal specimens from cattle and wild rodents.

As part of a study on the presence of Giardia cysts in water, a commercial direct immunofluorescence (DIF) test for the cysts was evaluated and compared to phase contrast microscopy. Forty faecal samples were collected from cattle; 31 contained Giardia. All 31 samples were positive by DIF whereas only 17 were detected by microscopy. The detected Giardia cysts were identified as belonging to the G. duodenalis group. 216 faecal samples were collected from wild rodents (Apodemus flavicollis, A. sylvaticus and Clethrionomys glareolus); 103 contained Giardia. Cysts were detected in 97 samples by DIF and in 57 by microscopy; 51 samples were positive by both methods. Nineteen rodents harboured cysts which morphologically resembled G. duodenalis. Specific identification was possible only by phase contrast microscopy, but the results suggested that DIF was superior for the detection of Giardia cysts in faeces of the animals tested.