Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/14/2002
Publication Date: 6/1/2002
Citation: Trout, J.M., Santin-Duran, M., Higgins, J.A., Fayer, R. 2002. Prevalence of Giardia in Dairy Calves and Cross-species Transmission Potential. American Association of Veterinary Parasitologists Proceedings. p.71.
Technical Abstract: Fecal samples were collected from 1-6 week-old dairy calves at 2 commercial dairy farms in each of 3 states, Maryland, Pennsylvania, and Virginia. Feces were passed through sieves of decreasing mesh size and then subjected to CsCl density gradient centrifugation to remove fecal debris and concentrate cysts. The resulting preparation was stained with a commercial fluorescent labeled mAb, placed onto microscope slides, and examined with the aid of a fluorescence microscope. DNA was extracted from all samples for PCR analysis and gene sequencing. To obtain cysts for cross-transmission experiments, Giardia cysts were isolated from calves at the USDA research dairy, Beltsville, MD. Cysts were cleaned from fecal debris as described above. This Beltsville isolate has subesequently been propagated in neonatal dairy calves. Freshly isolated cysts from propagation calves were inoculated into the following species thus far: neonatal BALB/c mice, dexamethasone-treated and untreated adult C57bl6/n mice, Mongolian gerbils, and domestic pigs. Fecal samples from these animals were processed and examined as described above. Overall prevalence of Giardia in the calves sampled was 27%, and ranged from 11% to over 50%. There were considerable variations in management practices between farms. Cross-transmission studies revealed that while propagation calves could be readily infected with the Beltsville isolate, inoculation into other species did not result in cyst production. Preliminary PCR data indicated that fluorescence microscopy was as sensitive as PCR analysis at detecting Giardia in samples. Sequence analysis of a 500 bp fragment of the triose phosphate isomerase gene from several isolates and comparison to CDC reference strains indicates that they belong to the hoofed-livestock genotype.