Article

Longitudinal investigation of protozoan parasites in meat lamb farms in southern Western Australia

School of Veterinary and Biomedical Sciences, Murdoch University, Western Australia 6150, Australia.
Preventive Veterinary Medicine (Impact Factor: 2.17). 09/2011; 101(3-4):192-203. DOI: 10.1016/j.prevetmed.2011.05.016
Source: PubMed

ABSTRACT

In this study, 96 faecal samples were collected from pregnant Merino ewes, at two broad-acre, commercial sheep farms in southern Western Australia, on two separate occasions (16 and 2 weeks prior to lambing). Following lambing, 111 (Farm A) and 124 (Farm B) female crossbred lambs (2-6 weeks old), were individually identified using ear tags (a numbered tag and a radio-frequency tag). A total of 1155 faecal samples were collected only from these individually identified lambs on five separate sampling occasions. All samples were screened using PCR to detect Cryptosporidium (18S rRNA and actin loci) and Giardia duodenalis (glutamate dehydrogenase and triosephosphate isomerise loci). The overall prevalences (lambs positive for a parasite on at least one of the five samplings) at Farm A and B were 81.3% and 71.4%, respectively for Cryptosporidium and similarly 67.3% and 60.5% for Giardia, respectively. Cryptosporidium and Giardia prevalences at individual samplings ranged between 18.5 and 42.6% in lambs and were <10% in the ewes. Cryptosporidium xiaoi was the most prevalent species detected at all five samplings and was also isolated from lamb dam water on Farm B. Cryptosporidium ubiquitum was most commonly detected in younger lambs and Cryptosporidium parvum was detected in lambs at all five samplings, typically in older lambs and as part of a mixed species infection with C. xiaoi. A novel, possibly new genotype (sheep genotype I), was identified in six Cryptosporidium isolates from Farm B. Giardia duodenalis assemblage E was the most common genotype detected at all five samplings, with greater proportions of assemblage A and mixed assemblage A and E infections identified in older lambs. This longitudinal study identified high overall prevalences of Cryptosporidium and Giardia in lambs grazed extensively on pastures, while reinforcing that sampling a random selection of animals from a flock/herd on one occasion (point prevalence), underestimates the overall prevalence of these parasites in the flock/herd across an extended time period. Based on these findings, grazing lambs were identified as a low risk source of zoonotic Cryptosporidium and Giardia species/genotypes, with these protozoa detected at all five samplings in some lambs, indicating that these individuals were either unable to clear the naturally acquired protozoan infections or were repeatedly re-infected from their environment or other flock members.

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    • "DSE, dry sheep equivalent; BL, Border Leicester; SA, South Australia; Vic, Victoria; NSW, New South Wales, WA, Western Australia. DNA from samples from Western Australia was extracted as described in Sweeny et al. (2011). "
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    ABSTRACT: The prevalence and faecal shedding of Chlamydia spp. in sheep in Australia has not been well described. Two species-specific quantitative PCRs (qPCR) targeting the chlamydial outer membrane protein cell surface antigen gene (ompA) were validated and used to determine the prevalence and faecal shedding of C. abortus and C. pecorum from faecal samples of lambs at three sampling times (weaning, post-weaning and pre-slaughter) from eight farms in South Australia, New South Wales, Victoria and Western Australia. A total of 3412 faecal samples were collected and screened from approximately 1189 lambs across the four states. C. abortus was not detected in any of the samples screened. The overall prevalence of C. pecorum was 1027/3412 (30.1%) and median bacterial concentrations at weaning, post-weaning and pre-slaughter were 1.8 x 107, 1.2 x 107 and 9.6 x 105/g faeces, respectively. A subset of C. pecorum positive samples from each farm, (n = 48) were sequenced to confirm their identity. The present study demonstrates that C. pecorum is prevalent in Australian sheep, highlighting a need for further research on the impact of this bacterium on production.
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    • "e l s e v i e r . c o m / l o c a t e / y e x p r Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium andersoni, Cryptosporidium suis, Cryptosporidium xiaoi, Cryptosporidium fayeri, Cryptosporidium ubiquitum and Cryptosporidium scrofarum , with C. xiaoi, C. ubiquitum and C. parvum most prevalent (Ryan et al., 2005; Santin et al., 2007; Fayer and Santin, 2009; Giles et al., 2009; Yang et al., 2009; Robertson, 2009; Diaz et al., 2010a; Wang et al., 2010; Sweeny et al., 2011; Cacciò et al., 2013; Connelly et al., 2013). Three of these species; C. parvum, C. hominis and C. xiaoi have also been identified in goats (Giles et al., 2009; Robertson, 2009; Diaz et al., 2010b). "

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