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→Laboratory Tests
===Laboratory Tests===
===Laboratory Tests===
Diagnosis is confirmed by demonstrating ''[[Giardia]]'' antigen, trophozoites or cysts in the faeces. The simplest method is to stain a fresch faecal smear with Diff-Quik or Lugol's iodine to reveal trophozoites. ''[[Giardia]]'' trophozoites are approximately 8 x 15 microns in dimension, tear-drop shaped organisms and contain two nuclei. They can be seen to move in a "falling leaf" pattern in wet mounts. As cysts are relatively "heavy", cysts must be floatated in higher density solutions prior to visualisation. Suitable solutions include zinc sulphate solution and sugar flotation solution. Centrifugal flotation in zinc sulphate solution is preferred as cysts can be envisaged with minimal distortion. Cysts are around 12 microns long and, if not distorted, oval in shape. When looking for cysts, three samples collected at two to three day intervals should be examined as shedding is intermittent.
Diagnosis is confirmed by demonstrating ''[[Giardia]]'' antigen, trophozoites or cysts in the faeces. The simplest method is to examine fresh faecal smears for cysts (and occasional trophozoites), but sensitivity is improved by using concentration techniques. Centrifugal flotation in zinc sulphate solution or sugar flotation solution are both appropriate, but zinc sulphate solution is preferred as it causes minimal distoryion to cysts. In this technique, faecal material is centrifuged and saturated with zinc sulphate mixture before the fluid from the top of the tube is placed on a microscope slide. Diff-Quik or Lugol's iodine are used to stain cysts and trophozoites, a coverslip is applied, and the slide is examined under the microscope. Although infrequently detected, ''[[Giardia]]'' trophozoites are approximately 8 x 15 micron tear-drop shaped organisms which contain two nuclei. They can sometimes be seen to move in a "falling leaf" pattern. Cysts are around 12 microns long and, if not distorted, oval in shape. When looking for cysts, three samples collected at two to three day intervals should be examined as shedding is intermittent.
Commercial ELISA tests are now available for the detection of ''[[Giardia]]'' antigen in faeces. These include the Snap ''[[Giardia]]'' test from IDEXX and the ProSpectT/Giardia ELISA from Alexon-Trend.
Commercial ELISA tests are now available for the detection of ''[[Giardia]]'' antigen in faeces. These include the Snap ''[[Giardia]]'' test from IDEXX and the ProSpectT/Giardia ELISA from Alexon-Trend.