title: 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.
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 63-1.3×10(9) cysts g(-1) (median=1.7×10(4)), 63-1.1×10(9) cysts g(-1) (median=9.6×10(3)), 63-4.7×10(9) cysts g(-1) (median=8.1×10(4)) 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.
authors.affiliation: School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.
authors.forename: Rongchang
authors.initials: R
authors.lastname: Yang
authors.affiliation: School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.
authors.forename: Caroline
authors.initials: C
authors.lastname: Jacobson
authors.affiliation: School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia.
authors.forename: Graham
authors.initials: G
authors.lastname: Gardner
authors.affiliation: South Australian Research and Development Institute, 33 Flemington Street, Glenside, SA 5065, Australia.
authors.forename: Ian
authors.initials: I
authors.lastname: Carmichael
authors.affiliation: Faculty of Veterinary Science, University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
authors.forename: Angus J D
authors.initials: AJ
authors.lastname: Campbell
authors.affiliation: School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia. Electronic address: Una.Ryan@murdoch.edu.au.
authors.forename: Una
authors.initials: U
authors.lastname: Ryan
mesh_terms: D000818:Animals; D001315:Australia / Q000453:epidemiology; D003598:Cytoskeletal Proteins / Q000235:genetics; D005243:Feces / Q000469:parasitology; D005838:Genotype; D005872:Giardia / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005873:Giardiasis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D005969:Glutamate Dehydrogenase / Q000235:genetics; D008137:Longitudinal Studies; D008969:Molecular Sequence Data; D033661:Oocysts; D015995:Prevalence; D015800:Protozoan Proteins / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary*; D012680:Sensitivity and Specificity; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology* / Q000469:parasitology*; D014305:Triose-Phosphate Isomerase / Q000235:genetics; D014886:Weaning
chemical_list: D003598:Cytoskeletal Proteins; D015800:Protozoan Proteins; C038207:giardin protein, Giardia lamblia; D005969:Glutamate Dehydrogenase; D014305:Triose-Phosphate Isomerase
keywords: Assemblage A and E; Beta-giardin; Giardia; Lambs; gdh; qPCR; tpi