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Development of a quantitative PCR (qPCR) for Giardia and analysis of the prevalence, cyst shedding and genotypes of Giardia present in sheep across four states in Australia

Yang, R., Jacobson, C., Gardner, G., Carmichael, I., Campbell, A.J.D. and Ryan, U. (2014) Development of a quantitative PCR (qPCR) for Giardia and analysis of the prevalence, cyst shedding and genotypes of Giardia present in sheep across four states in Australia. Experimental Parasitology, 137 . pp. 46-52.

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Link to Published Version: http://dx.doi.org/10.1016/j.exppara.2013.12.004
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Abstract

A novel quantitative PCR (qPCR) for Giardia at the glutamate dehydrogenase (gdh) locus was developed and validated. The qPCR was used to screen a total of 3412 lamb faecal samples collected from approximately 1189 lambs at three sampling periods (weaning, post-weaning and pre-slaughter) from eight farms across South Australia (SA), New South Wales (NSW), Victoria (Vic) and Western Australia (WA). The overall prevalence was 20.2% (95% CI 18.9-21.6) and of the 690 positives, 473 were successfully typed. In general, the prevalence of Giardia varied widely across the different farms with the highest prevalence in one WA farm (42.1%) at pre-slaughter sampling and the lowest prevalence in one Victorian farm (7.2%) at weaning. The range of cyst shedding at weaning, post-weaning and pre-slaughter overall across all states was 63-1.3×109 cysts g-1 (median=1.7×104), 63-1.1×109 cysts g-1 (median=9.6×103), 63-4.7×109 cysts g-1 (median=8.1×104) respectively. Assemblage specific primers at the triose phosphate isomerase (tpi) locus identified assemblage A in 22.4% (106/473) of positive samples typed, assemblage E in 75.9% (359/473) and mixed A and E assemblages in 1.7% (8/473) of samples. A subset of representative samples from the 8 farms (n=32) were typed at both the gdh and beta-giardin loci and confirmed these results and identified sub-assemblage AII in 16 representative assemblage A isolates across the 8 farms. This demonstrates a prevalence of Giardia previously not recognised in Australian sheep, highlighting a need for further research to quantify the production impacts of this protozoan parasite.

Publication Type: Journal Article
Murdoch Affiliation: School of Veterinary and Life Sciences
Publisher: Academic Press
Copyright: © 2013 Elsevier Inc.
URI: http://researchrepository.murdoch.edu.au/id/eprint/20787
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