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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.ORCID: 0000-0003-2563-2015, Jacobson, C.ORCID: 0000-0001-9427-1941, Gardner, G.ORCID: 0000-0001-7499-9986, Carmichael, I., Campbell, A.J.D. and Ryan, U.ORCID: 0000-0003-2710-9324 (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.

Item 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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