ORCID Profile
0000-0001-9427-1941
Current Organisation
Murdoch University
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Publisher: Wiley
Date: 12-2021
DOI: 10.1111/AVJ.13040
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.PREVETMED.2018.02.004
Abstract: Associations between faecal shedding of pathogenic Yersinia enterocolitica (based on the yst virulence gene) with growth, carcass weight and diarrhoea were investigated using an observational longitudinal study of 1200 crossbred prime (meat) lambs on eight Australian farms. Live weight, breech faecal soiling score (scale 1-5) and faecal consistency score (FCS scale 1-5) were recorded, and faecal s les collected from each lamb on three s ling occasions weaning (≈12 weeks of age), post-weaning (≈19 weeks) and pre-slaughter (≈29 weeks). Hot standard carcass weight was measured at slaughter. Faecal s les were screened for presence and concentration of pathogenic Y. enterocolitica using quantitative PCR. Associations of pathogenic Y. enterocolitica detection and shedding intensity with lamb health and production were assessed using general linear models (carcass weight), linear mixed effects models (live weight, FCS and breech soiling score) and non-parametric tests (FCS and breech soiling score). Prevalence for non-pelleted faeces (FCS ≥ 3.0) and diarrhoea (FCS ≥ 4.0) were compared with the two-tailed z-test, odds ratios and relative risk. Lambs shedding pathogenic Y. enterocolitica were 3.78 kg lighter post-weaning (P < 0.001) and 2.61 kg lighter pre-slaughter (P = 0.035) compared to lambs in which pathogenic Y. enterocolitica was not detected. Higher faecal concentration of pathogenic Y. enterocolitica was associated with lower live weight (P < 0.001). There was no association between pathogenic Y. enterocolitica detection and carcass weight. Overall, there was no evidence of association between pathogenic Y. enterocolitica detection and diarrhoea (higher FCS, higher risk for non-pelleted faeces or diarrhoea, or higher breech soiling score). Only one flock had increased relative risk for non-pelleted faeces associated with pathogenic Y. enterocolitica detection, and one other flock had increased relative risk for diarrhoea associated with pathogenic Y. enterocolitica detection. This is the first report of an association between reduced sheep live weight and pathogenic Y. enterocolitica based on the presence of the yst gene for heat stable enterotoxin determined by qPCR in sheep. Notably, impacts on live weight were observed in the absence of diarrhoea.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.VETPAR.2016.08.003
Abstract: Associations between intensity and frequency of Cryptosporidium and Giardia shedding with growth, carcase weight and dressing% were investigated using a longitudinal study of 1182 lambs on eight Australian farms. Live weight was recorded and faecal s les were collected on three s ling occasions weaning (approximately 12 weeks of age), post-weaning (approximately 19 weeks) and pre-slaughter (approximately 29 weeks). Hot standard carcase weight (HSCW) and dressing% were measured at slaughter. Faecal s les were screened for presence and concentration of Cryptosporidium, Giardia and Haemonchus oocysts using a quantitative PCR. Trichostrongylid eggs were quantified with modified McMaster faecal worm egg count (WEC). Protozoan shedding intensity was categorised as high (above median oocyst concentration in positive sheep), low (below median oocyst concentration in positive sheep) or not detected. Shedding was also categorised for shedding type (no shedding, single Giardia infection, single Cryptosporidium infection, concurrent Giardia and Cryptosporidium infection) and lambs were categorised for frequency of shedding (shedding identified on 0, 1, 2 or 3 occasions). Associations of parasite shedding intensity category, shedding type, shedding frequency, WEC and Haemonchus status (positive or negative) with lamb production were assessed using general linear models (HSCW and dressing%) and linear mixed effects models (live weight). High Cryptosporidium parvum shedding was associated with lower live weight, ranging 2.31-4.52kg over the 3 s ling occasions. Cryptosporidium parvum shedding was associated with less HSCW in high (3.22kg less) and low (3.22kg less) shedding lambs post-weaning, and high (2.21kg less) and low (2.60kg less) shedding lambs pre-slaughter as well as lower dressing% (2.7% lower in high shedding lambs post-weaning). Cryptosporidium (all species) shedding pre-slaughter was associated with reduced dressing% in both high (1.25% lower) and low (1.21% lower) shedding lambs. Giardia shedding pre-slaughter was associated with 0.59kg less HSCW in high shedding lambs. Increased frequency of C. parvum and Giardia shedding in a specific animal (repeated detection) were associated with reduced HSCW and dressing%. Concurrent Giardia and Cryptosporidium shedding pre-slaughter was associated with reduced dressing%. No statistically significant main effects for either WEC (P>0.05) or Haemonchus status (P>0.05) were identified for any of the sheep meat productivity measures (live weight, HSCW and dressing%). The findings suggest naturally acquired Cryptosporidium and Giardia infections in grazing sheep are associated with depressed growth, carcase weight and dressing efficiency beyond the neonatal period in sheep representing a range of genetic backgrounds and different sheep production environments.
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.PREVETMED.2011.05.016
Abstract: In this study, 96 faecal s les 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 in idually identified using ear tags (a numbered tag and a radio-frequency tag). A total of 1155 faecal s les were collected only from these in idually identified lambs on five separate s ling occasions. All s les 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 s lings) 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 in idual s lings 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 s lings 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 s lings, 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 s lings, 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 s ling 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 s lings in some lambs, indicating that these in iduals were either unable to clear the naturally acquired protozoan infections or were repeatedly re-infected from their environment or other flock members.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Springer Science and Business Media LLC
Date: 03-09-2021
DOI: 10.1186/S13071-021-04966-1
Abstract: Strongyloides westeri is found in the small intestine of young horses, mainly in foals up to about 16 weeks of age. The main source of infection for foals is through transmammary transmission, and foals can develop acute diarrhoea, weakness, dermatitis and respiratory signs. The epidemiology of S. westeri in Australia is largely unknown. Further, molecular techniques have never been employed for detection of S. westeri in horses. This pilot study aimed to assess the utility of a molecular phylogenetic method for the detection of S. westeri in the faeces of foals. Faecal s les were collected from a foal of less than 2 months of age, and eggs of Strongyloides sp. were detected using the modified McMaster technique. DNA was extracted from purified eggs, and a partial fragment of the small subunit of the nuclear ribosomal DNA (18S) was characterised using polymerase chain reaction, DNA sequencing and phylogenetic methods. Microscopic examination of faeces revealed small ellipsoidal eggs typical of Strongyloides sp. The 18S sequence generated by PCR in this study revealed 98.4% identity with that of a reference sequence of S. westeri available from GenBank. Phylogenetic analyses revealed a polyphyletic clustering of S. westeri sequences. This is the first study reporting the detection of DNA of Strongyloides sp. in faeces of a foal using a molecular phylogenetic approach targeting the variable region of 18S rDNA. It is anticipated that this study will allow future molecular epidemiological studies on S. westeri in horses.
Publisher: MDPI AG
Date: 08-09-2021
DOI: 10.3390/PATHOGENS10091157
Abstract: Traditional methods of detecting Chlamydia pecorum in tissue s les such as polymerase chain reaction or cell culture are laborious and costly. We evaluated the use of a previously developed C. pecorum LAMP assay using minimally processed ovine s les. Cotyledon (n = 16), foetal liver (n = 22), foetal lung (n = 2), and vaginal (n = 6) swabs, in addition to cotyledon (n = 6) and foetal liver (n = 8) tissue s les, were rapidly processed and used for LAMP testing without DNA extraction. Overall, LAMP test results were highly congruent with the in-house reference qPCR, with 80.43% (37/46 72.73% positive agreement (PA) 84.75% negative agreement (NA)) overall agreeance for swab s les, and 85.71% (12/14 80% PA 88.89% NA) overall agreeance for tissue s les. Out of the 11 total discrepant results, discrepancy was mainly observed in s les (n = 10) with less than 100 copies/µL C. pecorum DNA. While sensitivity could be improved, the simplicity, low cost, and accuracy of detection makes this test amenable for use at point-of-care for detecting C. pecorum in sheep.
Publisher: Wiley
Date: 25-04-2016
DOI: 10.1111/AVJ.12428
Abstract: To develop molecular tools for the investigation of the prevalence, species and faecal shedding of Yersinia in sheep. A quantitative PCR (qPCR) targeting the β subunit of the Yersinia spp. RNA polymerase gene was developed and validated. The prevalence of pathogenic Y. enterocolitica was determined by screening for the virulent yst gene. These qPCR assays were used to determine Yersinia spp. prevalence and faecal shedding concentration from 3412 faecal s les collected from approximately 1189 lambs (100-180 lambs/flock) on eight farms across Australia. This was a longitudinal study, with sheep s led on three occasions (weaning, post-weaning and pre-slaughter). A subset of up to five positive s les from each s ling on each farm (n = 111) was sequenced. Yersinia spp. (including both pathogenic and non-pathogenic species) were identified in all flocks, with 60.7% of lambs shedding Yersinia spp. on at least one s ling occasion. Point prevalence ranged from 4% to 91% across farms and s ling occasions. Median Yersinia spp. bacterial concentration was 1.1 × 10(6) , 2.8 × 10(6) and 5.6 × 10(5) organisms/g faeces at weaning, post-weaning and pre-slaughter, respectively, across all farms. Pathogenic Y. enterocolitica was identified in all eight flocks s led, with 14.8% of lambs shedding pathogenic Y. enterocolitica on at least one s ling occasion. Yersinia spp. and pathogenic Y. enterocolitica in particular were commonly identified in a s le of Australian sheep flocks using molecular techniques. Further studies into associations between faecal shedding of pathogenic Yersinia spp. and sheep productivity or clinical disease may utilise qPCR in conjunction with other diagnostic tools.
Publisher: Elsevier BV
Date: 02-2014
DOI: 10.1016/J.VETPAR.2013.11.014
Abstract: The prevalence of Cryptosporidium in sheep in the eastern states of Australia has not been well described, therefore a study of the prevalence, oocyst concentration, species and subtypes of Cryptosporidium were assessed from lamb faecal s les at three s ling periods (weaning, post-weaning and pre-slaughter) from eight farms across South Australia, New South Wales, Victoria and Western Australia. A total of 3412 faecal s les were collected from approximately 1182 lambs across the four states and screened for the presence of Cryptosporidium using a quantitative PCR (qPCR) at the actin locus. Positives were typed at the 18S locus and at a second locus using C. parvum and C. hominis specific qPCR primers. The overall prevalence was 16.9% (95% CI: 15.6-18.1%) and of the 576 positives, 500 were successfully genotyped. In general, the prevalence of Cryptosporidium was higher in WA than the eastern states. Cryptosporidium prevalence peaked at 43.9% and 37.1% at Pingelly (WA2) and Arthur River (WA1), respectively during weaning and at Pingelly (WA2) during pre-slaughter (36.4%). The range of oocyst shedding at weaning overall across all states was 63-7.9×10(6) and the median was 3.2 × 10(4) oocysts g(-1). The following species were identified C. xiaoi (69%-345/500), C. ubiquitum (17.6%-88/500), C. parvum (9.8%-49/500), C. scrofarum (0.8%-4/500), mixed C. parvum and C. xiaoi (2.4%-12/500), C. andersoni (0.2%-1/500) and sheep genotype 1 (0.2%-1/500). Subtyping of C. parvum and C. ubiquitum isolates identified IIa and IId subtype families within C. parvum (with IId as the dominant subtype) and XIIa within C. ubiquitum. This is the first published description of C. parvum subtypes detected in lambs in Australia.
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.TVJL.2014.08.001
Abstract: Faecal excretion of C ylobacter spp. and Salmonella enterica in sheep in Australia was determined using a quantitative multiplex PCR (qPCR) targeting the C ylobacter spp. purine biosynthesis gene (PurA) and the S. enterica outer membrane protein (ompF). The mutiplex qPCR was specific and C ylobacter spp. and S. enterica were each detected with a sensitivity of 5 organisms/µL faecal DNA extract. This multiplex qPCR was used to determine the prevalence and concentration of C ylobacter spp. and S. enterica in 3412 faecal s les collected from 1189 lambs on eight farms across South Australia (n = 2 farms), New South Wales (n = 1), Victoria (n = 2) and Western Australia (n = 3) at three s ling periods (weaning, post-weaning and pre-slaughter). The overall prevalences of C ylobacter spp. and S. enterica were 13.3% and 5.0%, respectively, with the highest prevalence for C ylobacter spp. in South Australia and the highest prevalence for S. enterica in New South Wales. C ylobacter jejuni was the only C ylobacter sp. identified from a subset of 120 positive s les sequenced at the 16S locus. S. enterica serovar Typhimurium was the only serovar of S. enterica identified from a subset of 120 positive s les sequenced at the ompF locus. Across all states, C ylobacter spp. had the highest median bacterial concentration in faeces at weaning and post-weaning (medians of 3.4 × 10(6) and 1.1 × 10(5), respectively), whereas S. enterica had the highest median bacterial concentration at pre-slaughter (1.8 × 10(5)/g faeces).
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.VETPAR.2011.03.015
Abstract: Two flocks of pure bred Dorper lambs were managed separately according to sex (283 ewe lambs and 212 ram lambs) in southern Western Australia. Faecal s le collection, weighing and body condition assessments were performed for each lamb on 2 occasions, specifically pre-weaning (approximately 14 weeks of age) and post-weaning (approximately 9 months of age). Body condition score (BCS) was assessed using a scale of 1 (very thin, emaciated) to 5 (excessively fat). Faecal worm egg counts (WECs) were measured using a modified McMaster technique and larval cultures were performed to identify trichostrongylid nematode genera present. Eye muscle and c-site fat depths were measured using ultrasound at post-weaning. Lambs received an abamectin anthelmintic treatment at weaning (18 weeks of age). Worm egg count data was assessed for normality of data distribution and homogeneity of variance. This data was transformed using log(10)(WEC+25) to stabilise variances between groups prior to statistical analyses and general linear models were used to assess relationships between WEC and productivity measures. Mean WECs were 564 eggs per gram of faeces (EPG) and 514 EPG at pre- and post-weaning in the ewe flock and 552 EPG and 480 EPG at pre- and post-weaning in the ram flock. Teladorsagia (Ostertagia) circumcincta, Trichostrongylus spp. and Oesophagostomum spp. larvae were identified. No lambs with WEC 1000 EPG post-weaning. Ewe and ram lambs with WEC>1000 EPG at pre-weaning were 42 (12-145 95% CI) and 37 (9-153) times more likely to have WEC>1000 EPG at post-weaning than lambs with WEC 501-1000 EPG at pre-weaning. There were no significant relationships between WEC and live weight in the ram flock, while relationships between WEC and live weight were inconsistent in the ewe lamb flock. There was no relationship between WEC and eye muscle or c-site fat depth. Significant negative relationships between WEC and BCS were identified at pre- and post-weaning for both flocks. Lambs with WEC 1000 EPG at pre- and post-weaning. In conclusion, high WEC was associated with lower body condition in Dorper lambs, however the relationship between WEC and live weight was inconsistent and there was no effect on eye muscle depth.
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.VETPAR.2009.07.018
Abstract: Nine flocks of sheep with a high prevalence (>30%) of diarrhoea and severe breech faecal soiling were investigated over a three-year period to examine the causes of diarrhoea in sheep with low mean faecal worm egg counts (WEC). All nine flocks were located in the southwest of Western Australia in areas with a winter rainfall pattern (Mediterranean climate). There was no difference (p=0.304) in WEC of diarrhoeic sheep (loose faeces and severe breech faecal soiling) and "normal sheep" (pelleted faeces and mild or no breech faecal soiling). Teladorsagia (Ostertagia) circumcincta and Trichostrongylus spp. were the nematodes most commonly identified by total worm counts and differentiation of larvae recovered from faeces and pasture. Larval stages of strongyle worms accounted for the largest proportion of total worm counts in both diarrhoeic and normal sheep. Adult worm burdens were small in most sheep. Diarrhoeic sheep had higher numbers of fourth stage larvae than normal sheep (p=0.046). There was no histopathological evidence of bacterial or viral causes of diarrhoea in any of the flocks or bacteriological evidence of bacterial infections associated with diarrhoea. Two flocks had marginal selenium glutathione peroxidase (selenium) levels. One flock was diagnosed with helminthosis based on rising WEC and high total worm counts. Larval hypersensitivity diarrhoea, nutritional factors or a combination of these two factors were the most likely causes of diarrhoea in the other eight flocks based on exclusion of other known causes of diarrhoea. Treatment with moxidectin and an ivermectin controlled-release capsule did not change faecal moisture content of treated sheep compared to untreated sheep three to five weeks after treatment. The findings suggest that the immune response to strongyle larvae may explain some cases of low WEC diarrhoea observed during winter-spring in immunocompetent mature sheep grazing in Mediterranean environments.
Publisher: SAGE Publications
Date: 19-11-2021
Abstract: Chlamydia pecorum is an obligate intracellular pathogen with a wide host range including livestock such as sheep, cattle, goats, and pigs as well as wildlife species such as koalas. Chlamydial polyarthritis is an economically important disease resulting in swollen joints, lameness, stiffness, and weight loss in young sheep. In the present study, tissues from sheep experimentally or naturally infected with Chlamydia pecorum were assessed by histopathology and immunohistochemistry. Carpal, hock, and stifle joints as well as spleen, liver, kidney, lymph nodes, lung, and brain of 35 sheep from different inoculation groups were available. Two different C. pecorum strains (IPA and E58), different routes of administration (intraarticular or intravenous), UVA-irradiated IPA strain, and corresponding noninfected control groups were investigated. Similar investigations on tissues from 5 naturally infected sheep were performed. The most obvious inflammatory lesions were observed in synovial tissues and, notably, in the renal pelvis from the experimentally infected group and naturally infected animals. This resulted in chronic or chronic-active arthritis and pyelitis. Intralesional chlamydial inclusions could be demonstrated by immunohistochemistry in both tissues. Immunohistochemical evaluation of the presence and distribution of macrophages, T and B cells in synovial tissues revealed macrophages as the most prevalent inflammatory cell population. Previous observations indicated that C. pecorum isolates can infect circulating monocytes. Together with the finding of the histological lesions in synovial tissues and internal organs alongside the presence of C. pecorum DNA, these observations suggest chlamydial arthritis in lambs is the result of hematogeneous spread of C. pecorum.
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.VPRSR.2017.05.001
Abstract: Faecal shedding of Eimeria by captured rangeland goats (Capra hircus) was investigated using a longitudinal observational study. Faecal s les were collected from 125 male goats on four occasions. The first s ling occurred following capture and transport, immediately after arrival at a commercial goat depot (feedlot) in Western Australia, with subsequent 3 s le collections occurring at one month intervals thereafter. Goats were composite breed and aged approximately 9-12months on arrival at the feedlot. Prevalence and shedding intensity (faecal oocyst concentration) for Eimeria were determined using qPCR. Species were identified from in idual oocysts (isolated using micromanipulation) using molecular analysis at two loci, specifically 18S rRNA and mitochondrial cytochrome oxidase gene (COI), and confirmed by microscopy. Longitudinal prevalence (animals positive at least once) for Eimeria spp. by qPCR was 90.4%, with 60% goats shedding Eimeria spp. on more than one occasion. Point prevalence (prevalence at a single s ling occasion) ranged from 2.4% (fourth s ling) to 70.4% (second s ling). Three species were identified at the 18S rRNA locus and confirmed by microscopy: E. christenseni (longitudinal prevalence for single infection 34.4%), E. hirci (17.6%) and E. arloingi (8.8%) over the four s le collections. Mixed infections were identified in 56.8% goats (longitudinal prevalence). 18S rRNA sequences from E. christenseni and E. hirci were 100% homologous with ovine E. ahsata and E. crandallis respectively, and E. arloingi was 100% similar to caprine E. arloingi. At the COI locus, E. christenseni, E. hirci and E. arloingi grouped separately, and were closely related to ovine E. ahsata, with genetic similarities of 96.5%, 92.6% and 91.4% respectively. This is the first report for molecular characteristics of caprine-derived Eimeria spp. using a combination of 18S rRNA and COI. Molecular techniques can be used to identify Eimeria spp. in goat faecal s les, specifically through characterization at 18S locus and other gene loci when used in parallel. Molecular techniques offer some advantages over microscopy for identification of Eimeria species, particularly with respect to precision.
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.TVJL.2014.05.037
Abstract: The prevalence and faecal shedding of Chlamydia spp. in sheep in Australia has not been well described. Two species-specific quantitative PCRs (qPCRs) 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 s les of lambs at three s ling 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 s les were collected and screened from approximately 1189 lambs across the four states. C. abortus was not detected in any of the s les 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 × 10(7), 1.2 × 10(7) and 9.6 × 10(5)/g faeces, respectively. A subset of C. pecorum positive s les from each farm, (n = 48) was 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.
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.VETPAR.2012.01.007
Abstract: Faecal s les (n=1155) were collected from n=111 (Farm A) and n=124 (Farm B) 2-6 week old female lambs on two farms in southern Western Australia across five s ling occasions (spanning 8 months). Genomic DNA was extracted directly from faecal s les and screened by PCR for ITS-2 nuclear ribosomal DNA to detect patent strongylid infections, specifically Teladorsagia circumcincta, Trichostrongylus spp., Haemonchus contortus, Oesophagostomum spp. and Chabertia ovina. The minimum amount of extracted genomic DNA necessary for successful PCR lification was 2.0-5.0 pg. During the five s ling occasions for the two farms, the sensitivities for WEC and PCR identification of strongylid infections varied, with levels of agreement between the two sets of diagnostic results ranging from 85 to 100%. Strongylid species prevalences were high (90.3-97.3%), with T. circumcincta and Trichostrongylus spp. the most prevalent species and together they were the most common mixed strongylid infection H. contortus was not identified in either flock. T. circumcincta was the only species associated with an increased risk of non-pelleted faeces on Farm B, where T. circumcincta-positive lambs were 2.3 and 2.6 times more likely to have non-pelleted faeces than negative lambs at the second and final s lings, respectively. The highest strongylid prevalence, mixed strongylid prevalence and mean number of strongylid species detected per lamb coincided with the highest average flock faecal worm egg counts (WECs) on both farms. There was a positive correlation between the number of strongyle species detected per lamb and both WEC and adjusted WEC (P<0.01 r(2) 0.026-0.591). These results indicate that strongylid eggs were likely to be the main source of strongylid DNA in the faecal DNA extracts. Despite the progress made by the molecular approach utilised in this study, it is incapable of distinguishing between patent and non-patent sources of strongylid DNA. However there is potential for further investigation into the development of a similar molecular procedure which could be used for early larvae detection on pastures.
Publisher: MDPI AG
Date: 21-12-2021
DOI: 10.3390/ANI12010010
Abstract: The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3–71.1%) for the ewe lambs and 29.4% (range 19.7–52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0–50%) in the ewe lamb flocks and 0.9% of ewes (range 0–4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting ≥2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.MOLBIOPARA.2011.07.007
Abstract: Patent strongylid nematode infections were identified using McMaster worm egg counts (WEC) and PCR assays (ITS-2 nuclear ribosomal DNA) to screen genomic DNA extracted directly from lamb faecal s les. Lambs from four different farms in southern Western Australia were s led rectally on two separate occasions, with McMaster WECs and PCRs conducted on a total of 858 s les. Negative controls (n=96) (WEC <50 eggs per gram [epg]) and positive controls (n=96) (faecal s les spiked with a 100 μL suspension of third-stage larvae (L(3)) containing approximately equal proportions of Teladorsagia circumcincta, Trichostrongylus colubriformis, Haemonchus contortus, Oesophagostomum spp. and Chabertia ovina) were generated. All control s les lified in accordance with positive controls. High levels of agreement (Kappa values ≥ 0.93) were identified between the two diagnostic tests. PCRs detected an additional 2.0% of s les as strongylid-positive but there was no significant difference in the number of strongylid-positive s les identified using PCR or McMaster WEC.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/AN12143
Abstract: This study investigated the effect of nutrition on wool harvesting efficiency of a biological wool harvesting system (Bioclip) utilising epidermal growth factor (EGF) to induce shedding of the fleece. The experiment had nine groups, each representing a different growth path based on a 3 by 3 design with three levels of nutrition (low, medium and high) fed during two periods, specifically the pre-injection period (4-weeks leading up to EGF injection) and post-injection period (4 weeks between EGF injection and wool harvesting). Sheep weight and body condition score were measured at the start and end of each period. Wool harvesting efficiency, fleece weight and body wrinkle were assessed at wool harvesting. Continuous data were analysed using general linear models and linear regression. Bivariate categorical data were analysed using Chi-squared tests and odds ratios. Wool harvesting efficiency was reduced in sheep with greater skin wrinkle (P 0.001), poorer body condition (P 0.001) and poorer nutrition in both pre- and post-injection periods (P 0.001). Sheep that gained 1 kg bodyweight or 0.5 body condition score either pre- or post-injection had improved wool harvestability (P 0.05). Sheep that lost weight post-injection were 10.2 (95% confidence interval 4.0, 25.5) times and 4 times (2.4, 6.7) more likely to have very poor harvestability compared with sheep that gained or maintained weight respectively (P 0.001). Sheep with greater body wrinkle were 6.6 (4.1, 10.7) times more likely to have very poor harvestability than plain-bodied sheep (P 0.001). Nutrition that ensures modest weight gain during the pre- and post-injection periods can partially overcome poorer harvestability in wrinkly sheep.
Publisher: Mary Ann Liebert Inc
Date: 04-2016
Abstract: Bacteria of the genus Bartonella have been described in multiple mammalian hosts with many species capable of causing disease in humans. Cats and various species of rats have been reported to play a role as vertebrate hosts to a number of Bartonella spp. This study aimed to identify Bartonella spp. in Western Australia, Dirk Hartog Island (DHI), and Christmas Island (CI) and to investigate the presence of potential arthropod vectors. Feral cats were collected from CI (n = 35), DHI (n = 23) and southwest Western Australia (swWA n = 58), and black rats were collected from CI (n = 48). In iduals were necropsied, ectoparasites were collected by external examination of carcasses, and splenic tissue was collected for polymerase chain reaction analysis to detect Bartonella DNA. Bartonella henselae DNA was detected from two cats and Bartonella koehlerae DNA from one cat in southwest WA, but Bartonella DNA was not identified in cats on DHI or CI. Bartonella phoceensis (28/48 = 58.3%) and a novel Bartonella genotype (8/48 = 16.7%) based on the internal transcribed space region were detected in the spleens of black rats on CI. Detection of Bartonella spp. in each location corresponded to the presence of ectoparasites. Cats from southwest WA harbored four species of fleas, including Ctenocephalides felis, and black rats on CI were infested with multiple species of ectoparasites, including mites, fleas, and lice. Conversely, cats on Dirk Hartog and CI were free of ectoparasites. This study has identified the DNA of Bartonella species from island and mainland swWA with some (B. henselae and B. koehlerae) of known zoonotic importance. This study further extends the geographical range for the pathogenic B. koehlerae. The association of Bartonella with ectoparasites is unsurprising, but little is known about the specific vector competence of the ectoparasites identified in this study.
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.TVJL.2011.06.042
Abstract: Diarrhoea is a widespread problem for sheep enterprises worldwide. A cross-sectional epidemiological study was conducted using a questionnaire to determine the prevalence of diarrhoea and associated risk factors where there was evidence of recent diarrhoea (active diarrhoea or fresh faecal soiling of breech fleece) for meat lambs on farms in southern Western Australia during 2010. The response rate was 41.4% (139/336). Evidence of recent diarrhoea was reported on 64.8% of farms, with a mean of 6.9% lambs affected per farm. Location of a farm and a higher annual rainfall were associated with an increased diarrhoea prevalence. Binary logistic regression analysis suggested that the drinking water source was associated with the incidence of diarrhoea, since lamb flocks supplied with dam water were 117 times (95% CI: 18.2, 754.8) more likely to have observed diarrhoea or fresh breech fleece faecal soiling than lamb flocks supplied with other sources of water. Faecal worm egg counts were used by 65% of respondents to determine whether an anthelmintic treatment was warranted and 74% of respondents administered a treatment to their meat lambs. In response to a range of diarrhoea scenarios presented to respondents (5%, 25% and 50% of the flock with evidence of recent diarrhoea), 15.1% would have elected to administer an anthelmintic treatment regardless of differences in prevalence.
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/EA08251
Abstract: Diarrhoea (scouring) and subsequent faecal soiling of fleece are important economic and welfare issues for the sheep industry. Nematode worm infections are commonly implicated as a cause of scouring. This study aimed to investigate the extent of strongyle parasite infections, and identify any association with faecal worm egg count (WEC) and scouring in sheep from winter rainfall environments in Western Australia consigned to an abattoir. Faeces were collected from sheep with evidence of scouring and normal sheep (firm faecal pellets and no evidence of fresh diarrhoea on breech). A total of 4430 sheep from 113 lines of lambs ( months old), 10 lines of yearlings (12–24 months old) and 235 lines of adult sheep ( months old) were s led between September and January. Mean WEC in lamb lines was 1525 eggs per gram (epg) of faeces with mean WEC epg in 42% of lines and in 22% of lines. Mean WEC in adult lines was 486 epg, with 13% lines having mean WEC epg. There was a trend (P = 0.099) to higher WEC in scouring lambs (2289 epg) compared with normal lambs (1523 epg). The scouring adult sheep had lower WEC (417 epg) compared with normal adults (482 epg, P = 0.021). The findings suggest that large strongyle infections were common in lambs consigned for slaughter. The low WEC in scouring adult sheep was consistent with the suggestion that a hypersensitivity to ingested nematode larvae, rather than large worm burdens, may be responsible for scouring in mature sheep.
Publisher: Wiley
Date: 04-10-2016
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.VETPAR.2018.07.005
Abstract: Cryptosporidium and Giardia are common parasites of ruminant livestock worldwide. These parasites are associated with diarrhoea outbreaks in young goats (pre-weaning), but the impacts on health and productivity for older goats (post-weaning) are not well understood. Here we show Cryptosporidium faecal shedding is associated with reduced growth and diarrhoea in goats aged approximately 9-15 months. Goats were s led four times at one-month intervals. Faecal shedding for a range of pathogens were determined using quantitative PCR and sequencing (Cryptosporidium, Giardia, Eimeria, Salmonella, C ylobacter), and microscopy (trichostrongylid nematode worm egg count and Entamoeba). Cryptosporidium faecal shedding was associated with 1.5 kg lower growth for the one-month period following s ling. Specifically, C. xiaoi was associated with 1.9 kg lower growth in the following month. This is the first report of production impacts associated with C. xiaoi in ruminants older than 3 months of age. Cryptosporidium shedding was associated with an over 4-fold increase in risk of diarrhoea, with C. parvum associated with 10-fold and C. ubiquitum associated with 16-fold increase in risk of diarrhoea. Notably, C. xiaoi shedding was not associated with increased risk of diarrhoea. Giardia shedding was associated with looser faecal consistency, but not diarrhoea. Higher Eimeria oocyst counts were weakly associated with lower live weight, poorer body condition and looser faecal consistency. Shedding of other enteric pathogens were not associated with impacts on live weight, growth or diarrhoea risk. This study challenges the two notions that Cryptosporidium infections only impact health and productivity of goats during the pre-weaning period, and that Cryptosporidium (and specifically C. xiaoi) infections in the absence of diarrhoea are asymptomatic. Recognising the potential for impacts of Cryptosporidium infection on growth rates in the absence of diarrhoea will support improved design for experiments testing impacts of Cryptosporidium on ruminant health and production. Improved understanding of the role of protozoan infections on animal health has implications for the management of goats in order to reduce adverse impacts on farm profitability, animal welfare and public health risk.
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.PREVETMED.2015.08.004
Abstract: The investigation aimed to assess factors affecting the uptake of novel targeted selective treatment (TST) strategies by sheep farmers in Western Australia where the most common nematode species present were Teladosagia circumcincta, Trichostrongylus spp. and Nematodirus spp. ("scour worms"). The study used a questionnaire format with questions concentrated on current worm control practices and farmers' current understanding and adoption of putative TST strategies. Participants represented a range of environments (derived from four farming regions) and sheep management situations, and it is therefore likely that the results of this investigation will apply in other locations where scour worms predominate. Sixty-five percent of participants were aware of the TST concept and 25% had implemented it in some form. The awareness of the TST approach was greatest where sheep farmers were concerned about anthelmintic resistance, where tools such as worm egg counts and faecal worm egg count resistance tests were employed, and where professional advisers were consulted regarding worm control. Respondents that sought advice chiefly from rural merchandise retailers were considerably less (0.1-0.6 times) likely to be aware of these management tools or to be aware of TST approaches. The findings indicated that the adoption of TST strategies will require greater use of professional advisers for worm control advice by sheep farmers, and that advisers are conversant with TST concepts.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.VETPAR.2016.02.030
Abstract: This study utilised computer simulation modelling (Risk Management Model for Nematodes) to investigate the impact of different parasite refugia scenarios on the development of anthelmintic resistance and worm control effectiveness. The simulations were conducted for adult ewe flocks in a Mediterranean climatic region over a 20 year time period. Factors explored in the simulation exercise were environment (different weather conditions), drug efficacy, the percentage of the flock left untreated, the timing of anthelmintic treatments, the initial worm egg count, and the number of drenches per annum. The model was run with variable proportions of the flock untreated (0, 10, 20, 30, 40 and 50%), with ewes selected at random so that reductions in the mean worm burden or egg count were proportional to the treated section of the flock. Treatments to ewes were given either in summer (December low refugia potential, hence highly selective) or autumn (March less selective due to a greater refugia potential), and the use of different anthelmintics was simulated to indicate the difference between active ingredients of different efficacy. Each model scenario was run for two environments, specifically a lower rainfall area (more selective) and a higher rainfall area (less selective) within a Mediterranean climatic zone, characterised by hot, dry summers and cool, wet winters. Univariate general linear models with least square difference post-hoc tests were used to examine differences between means of factors. The results confirmed that leaving a proportion of sheep in a flock untreated was effective in delaying the development of anthelmintic resistance, with as low as 10% of a flock untreated sufficient to significantly delay resistance, although this strategy was associated with a small reduction in worm control. Administering anthelmintics in autumn rather than summer was also effective in delaying the development of anthelmintic resistance in the lower rainfall environment where all sheep were treated, although the effect of treatment timing on worm control effectiveness varied between the environments and the proportion of ewes left untreated. The use of anthelmintics with higher efficacy delayed the development of resistance, but the initial worm egg count or number of annual treatments had no effect on either the time to resistance development or worm control effectiveness. In conclusion, the modelling study suggests that leaving a small proportion of ewes untreated, or changing the time of treatment, can delay the onset of anthelmintic resistance in a highly selective environment.
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.VETPAR.2008.12.021
Abstract: A total of 477 faecal s les from pre-weaned sheep from 5 different farms in the south west of Western Australia were screened for the presence of Cryptosporidium and Giardia using PCR. There were substantial differences in prevalence between the farms and overall prevalence was 24.5% and 11.1%, respectively for Cryptosporidium and Giardia. At the 18S locus, 66 Cryptosporidium positives were identified, the majority of which were C. bovis (n=52), followed by the cervid genotype (n=10) and C. parvum (n=2). At a second diagnostic locus, using C. parvum and C. hominis-specific qPCR primers, 63 C. parvum positives were identified, some of which were co-infections with C. bovis. The C. parvum/C. hominis qPCR was more sensitive than the nested 18S PCR at detecting C. parvum. This may be due to the low numbers of oocysts present, as quantitation data indicated that all the C. parvum detected were present in low numbers (1-10 oocysts). It may also be that using C. parvum-specific primers is necessary to determine the true prevalence of C. parvum. Amongst Giardia positive isolates, G. duodenalis genotype E (livestock) was the most prevalent (36/53), with G. duodenalis genotype A detected in five positive isolates. There were also 11 mixed A and E infections detected. The findings of the present study indicate that pre-weaned lambs are not an important source of zoonotic Giardia genotypes in Australia but may be an important source of zoonotic Cryptosporidium.
Publisher: Mary Ann Liebert Inc
Date: 05-2017
Abstract: Leptospirosis is a neglected, re-emerging bacterial disease with both zoonotic and conservation implications. Rats and livestock are considered the usual sources of human infection, but all mammalian species are capable of carrying Leptospira spp. and transmitting pathogenic leptospires in their urine, and uncertainty remains about the ecology and transmission dynamics of Leptospira in different regions. In light of a recent case of human leptospirosis on tropical Christmas Island, this study aimed to investigate the role of introduced animals (feral cats and black rats) as carriers of pathogenic Leptospira spp. on Christmas Island and to compare this with two different climatic regions of Western Australia (one island and one mainland). Kidney s les were collected from black rats (n = 68) and feral cats (n = 59) from Christmas Island, as well as feral cats from Dirk Hartog Island (n = 23) and southwest Western Australia (n = 59). Molecular (PCR) screening detected pathogenic leptospires in 42.4% (95% confidence interval 29.6-55.9) of cats and 2.9% (0.4-10.2) of rats from Christmas Island. Sequencing of cat- and rat-positive s les from Christmas Island showed 100% similarity for Leptospira interrogans. Pathogenic leptospires were not detected in cats from Dirk Hartog Island or southwest Western Australia. These findings were consistent with previous reports of higher Leptospira spp. prevalence in tropical regions compared with arid and temperate regions. Despite the abundance of black rats on Christmas Island, feral cats appear to be the more important reservoir species for the persistence of pathogenic L. interrogans on the island. This research highlights the importance of disease surveillance and feral animal management to effectively control potential disease transmission.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.VETPAR.2017.01.013
Abstract: Uninucleated Entamoeba cysts measuring 7.3×7.7μm were detected in faecal s les collected from wild Rangeland goats (Capra hircus) after arrival at a commercial goat depot near Geraldton, Western Australia at a prevalence of 6.4% (8/125). Sequences were obtained at the 18S rRNA (n=8) and actin (n=5) loci following PCR lification. At the 18S locus, phylogenetic analysis grouped the isolates closest with an E. bovis isolate (FN666250) from a sheep from Sweden with 99% similarity. At the actin locus, no E. bovis sequences were available, and the isolates shared 94.0% genetic similarity with E. suis from a pig in Western Japan. This is the first report to describe the morphology and molecular characterisation of Entamoeba from Rangeland goats in Western Australia and the first study to produce actin sequences from E. bovis-like Entamoeba sp.
Publisher: Springer Science and Business Media LLC
Date: 02-10-2021
Publisher: Elsevier BV
Date: 12-2012
Publisher: No publisher found
Date: 2005
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 03-2016
Publisher: American Society for Microbiology
Date: 09-2005
DOI: 10.1128/AEM.71.9.4992-4997.2005
Abstract: Little is known of the prevalence of Cryptosporidium and Giardia parasites in sheep and the genotypes that they harbor, although potentially sheep may contribute significantly to contamination of watersheds. In the present study, conducted in Western Australia, a total of 1,647 sheep fecal s les were screened for the presence of Cryptosporidium and Giardia spp. using microscopy, and a subset ( n = 500) were screened by PCR and genotyped. Analysis revealed that although both parasites were detected in a high proportion of s les by PCR (44% and 26% for Giardia and Cryptosporidium spp., respectively), with the exception of one Cryptosporidium hominis isolate, the majority of isolates genotyped are not commonly found in humans. These results suggest that the public health risk of sheep-derived Cryptosporidium and Giardia spp. in catchment areas and effluent may be overestimated and warrant further investigation.
Publisher: Springer Science and Business Media LLC
Date: 11-06-2021
DOI: 10.1186/S13567-021-00950-W
Abstract: Lamb survival is an important welfare and productivity issue for sheep industries worldwide. Lower lamb survival has been reported for primiparous ewes, but the causes of this are not well studied. The aim of this study was to determine causes of perinatal deaths for lambs born to primiparous ewes in Western Australia, and identify if infectious diseases are implicated. Lamb mortality from birth to marking were determined for 11 primiparous ewe flocks on 10 farms in Western Australia. Lamb mortality from birth to marking averaged 14% for single-born and 26% for multiple-born lambs. Lamb necropsies ( n = 298) identified starvation–mismosthering–exposure (34%), dystocia (24%) and stillbirth (15%) as the most common causes of perinatal lamb death. There was no evidence of exotic abortigenic pathogens in aborted and stillborn lambs ( n = 35). Chlamydia pecorum was detected by qPCR in 15/35 aborted and stillborn lambs on 5/6 farms. Preliminary molecular characterisation of C. pecorum detected in s les from aborted and stillborn lambs ( n = 8) using both Multilocus Sequence Typing and omp A genotyping indicated all strains were genetically identical to previously described pathogenic livestock strains, denoted ST23, and dissimilar to gastrointestinal strains. High frequency of detection of a pathogenic C. pecorum strains ST23 associated with ovine abortion and stillbirth on multiple farms located across a wide geographic area has not been previously reported. Chlamydia pecorum may contribute to reproductive wastage for primiparous sheep in Western Australia. Further investigation to understand C. pecorum epidemiology and impact on sheep reproduction is warranted.
Publisher: Elsevier BV
Date: 03-2016
Publisher: Wiley
Date: 26-04-2017
DOI: 10.1111/AVJ.12572
Abstract: Develop a multiplex quantitative PCR assay to investigate the prevalence and shedding of Escherichia coli O157/O145, Salmonella spp. and C ylobacter spp. in sheep at sale yards and abattoirs. A qPCR for E. coli O157/O145 was developed, validated and multiplexed with an existing qPCR for C ylobacter and Salmonella enterica. The absolute numbers of E. coli O157/O145, C ylobacter and Salmonella in control s les was determined using droplet digital PCR. These were then used as the controls in the multiplex qPCR on a total of 474 sheep faecal s les collected from two saleyards over a 4-month period (April-July 2014) and 96 effluent s les from an abattoir. The mutiplex qPCR was specific with a sensitivity of 5 organisms/μL faecal DNA extract for C ylobacter, S. enterica and E. coli O157/O145. The overall prevalence of C ylobacter, S. enterica and E. coli O157/O145 in faecal s les was 5.7%, 3.6% and 8.4% and in effluent s les was 18.8%, 6.3% and 5.2%, respectively. The pathogen loads of C ylobacter, S. enterica and E. coli O157/O145 in faecal and effluent s les was also determined via mutiplex qPCR. The overall prevalences of C ylobacter, S. enterica and E. coli O157/O145 were generally low (<6%), but point prevalences ranged considerably in healthy sheep (up to 26% for E. coli O157/O145). Further work to determine risk factors for shedding of bacterial organisms in meat sheep in the pre-slaughter period (on-farm, sale yards and lairage at abattoirs) could further reduce the risk of contamination of meat products.
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.VPRSR.2016.11.006
Abstract: Faecal shedding of Cryptosporidium and Giardia by captured rangeland goats was investigated using a longitudinal study with four faecal s les collected from 125 male goats once monthly for four months, commencing immediately after capture and transport to a commercial goat depot (feedlot). Goats were composite breed and aged approximately 9-12months on arrival. Faecal s les were screened for Cryptosporidium and Giardia presence and concentration using quantitative PCR and sequencing at the 18S ribosomal RNA locus (Cryptosporidium), and glutamate dehydrogenase and β-giardin loci (Giardia). Longitudinal prevalence for Cryptosporidium was 27.2% (point prevalence range 3-14%) with 3 species identified: C. xiaoi (longitudinal prevalence 13.6%), C. ubiquitum (6.4%) and C. parvum (3.2%). Sub-typing at the gp60 locus identified C. ubiquitum XIIa, C. parvum IIaA17G2R1 and C. parvum IIaA17G4R1. This is the first report of the zoonotic C. parvum subtype IIaA17G4R1 in goats. The pattern of genotypes shed in faeces changed over the duration of study with C. ubiquitum identified only at the first and second s lings, and C. parvum identified only at the fourth s ling. Longitudinal prevalence for Giardia duodenalis was 29.6% (point prevalence range 4-12%) with all positives sub-typed as assemblage E. Only 2/125 goats were identified to be shedding Cryptosporidium or Giardia on more than one occasion. This is the first report of Cryptosporidium and Giardia genotypes in captured rangeland goats. Faecal shedding of zoonotic Cryptosporidium spp. and potentially zoonotic G.duodenalis has implications for food safety and effluent management. Keywords: Cryptosporidium Giardia Rangeland goats zoonotic.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 02-2014
DOI: 10.1016/J.EXPPARA.2013.12.004
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 s les collected from approximately 1189 lambs at three s ling 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 s ling 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 s les typed, assemblage E in 75.9% (359/473) and mixed A and E assemblages in 1.7% (8/473) of s les. A subset of representative s les 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.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.VETPAR.2011.08.016
Abstract: On two separate s ling occasions, faecal s les were collected from lambs (2-5 months of age) grazing pasture on two separate sheep farms in southern Western Australia. Live weight, body condition score (BCS), faecal consistency score (FCS) and faecal dry matter percentage (DM%) were measured. Faecal s les were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and β-giardin) and patent strongylid nematode infections (ITS-2 nuclear ribosomal DNA for Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp. Chabertia ovina and Oesophagostomum spp.). Faecal worm egg counts (WECs) were performed using a modified McMaster WEC technique. The WECs were adjusted for FCS and transformed using log(10)(adjusted WEC+25) prior to statistical analyses. Cryptosporidium, Giardia and Trichostrongylus spp. detected by PCR were associated with an increased risk of non-pelleted faeces (FCS ≥ 3.0) for both flocks. Cryptosporidium-positive lambs were 2.8-11.6 times more likely to have non-pelleted faeces and Giardia-positive lambs were 2.4-14.0 times more likely to have non-pelleted faeces compared to lambs negative for each respective parasite. Lambs positive for both Cryptosporidium and Giardia were 2.9-11.8 times more likely to have non-pelleted faeces than lambs positive for only one or neither of these parasites. Mixed internal parasite infections were found to have greater impacts on FCS and BCS than single infections. A higher number of internal parasites detected per lamb was associated with lower BCS and more loose faeces. The relationship between parasite detection and live weight or growth rate were inconsistent for both flocks. Adjusted WEC was correlated with FCS and faecal DM% for one flock only, although little or no correlation was found with live weight and growth rate for both flocks. Cryptosporidium ubiquitum and Cryptosporidium parvum were the most prevalent Cryptosporidium species isolated in the two flocks. Giardia assemblage E was the most commonly isolated genotype assemblage from both flocks, while assemblage A was isolated almost as frequently as assemblage E in the one flock. One flock was a potential source of zoonotic Cryptosporidium and the other flock was a potential source of zoonotic Giardia.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.EXPPARA.2014.06.018
Abstract: The prevalence of Eimeria in sheep in Australia has not been well described, therefore a quantitative PCR (qPCR) was developed, validated and used to study the prevalence and oocyst concentration in lamb faecal s les at three s ling periods (weaning, post-weaning and pre-slaughter) from eight farms across South Australia, New South Wales, Victoria and Western Australia. A total of 3412 faecal s les were collected from approximately 1182 lambs across the 4 states and screened for the presence of Eimeria using this qPCR at the 18S ribosomal RNA (rRNA) locus. A subset of positives was typed by sequence analysis at the 18S locus. The overall prevalence was 18.1% (95% CI 16.8-19.3%) and of the 616 positives, 118 were successfully genotyped. The prevalence of Eimeria was highest in NSW and peaked at 70% during the post-weaning period. The range of oocyst shedding per gram of faeces (g(-1)) at weaning, post-weaning and pre-slaughter overall across all states was 23-2.1×10(7), 23-1.3×10(7) and 23-2.1×10(5), respectively. Median Eimeria shedding g(-1) was higher during post-weaning (1.1×10(3)) and pre-slaughter (1.1×10(3)) than during weaning (206). The following species were identified: Eimeria crandallis, Eimeria ahsata, Eimeria ovinoidalis, Eimeria weybridgensis and Eimeria cylindrica. Of these, E. crandallis and E. ovinoidalis, the most pathogenic species in sheep were responsible for 58.5% of infections typed. This highlights a need for further research to quantify the production impacts of Eimeria in sheep.
Publisher: Elsevier BV
Date: 09-2015
Publisher: Elsevier BV
Date: 06-2020
Publisher: Cambridge University Press (CUP)
Date: 2016
DOI: 10.1017/PAO.2016.1
Abstract: Trypanosomes and Leishmania are vector-borne parasites associated with high morbidity and mortality. Trypanosoma lewisi , putatively introduced with black rats and fleas, has been implicated in the extinction of two native rodents on Christmas Island (CI) and native trypanosomes are hypothesized to have caused decline in Australian marsupial populations on the mainland. This study investigated the distribution and prevalence of Trypanosoma spp. and Leishmania spp. in two introduced pests (cats and black rats) for three Australian locations. Molecular screening (PCR) on spleen tissue was performed on cats from CI ( n = 35), Dirk Hartog Island (DHI n = 23) and southwest Western Australia (swWA) ( n = 58), and black rats from CI only ( n = 46). Despite the continued presence of the intermediate and mechanical hosts of T. lewisi , there was no evidence of trypanosome or Leishmania infection in cats or rats from CI. Trypanosomes were not identified in cats from DHI or swWA. These findings suggest T. lewisi is no longer present on CI and endemic Trypanosoma spp. do not infect cats or rats in these locations.
Publisher: Informa UK Limited
Date: 02-01-2018
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.VETPAR.2009.01.008
Abstract: Effects of gastrointestinal parasitism on sheep productivity are usually described using live weight change, however carcass productivity is more accurately described using dressing percentage (carcass weight as a proportion of live weight). This experiment had a 2x2x2 factorial design whereby 10-month-old Merino wethers were fed lucerne (Medicago sativa) diets (fresh lucerne or lucerne chaff) with 2 levels of carboxymethycellulose (CMC) inclusion (0% or 8% CMC) and nematode larval challenge (no larval challenge or 10,000 Teladorsagia circumcincta and 10,000 Trichostrongylus colubriformis per week). Sheep were weighed and euthanased 50 or 51 days after larval challenge and CMC supplementation commenced. Weight of the carcass (hot standard carcass weight) and gastrointestinal organs (full and empty) were recorded and expressed as a proportion of live weight. Larval challenged sheep had a worm egg count (mean+/-standard error) of 173+/-38 eggs per gram of faeces and total worm count of 30,237+/-2013 at slaughter. Larval challenged sheep had 1.3% lower dressing percentage (p=0.048), and 2% heavier full (p=0.007) and 1.2% heavier empty gastrointestinal tracts (p=0.012) compared to unchallenged sheep. There was no effect of CMC inclusion or lucerne type (fresh or chaff) on gastrointestinal tract weight or dressing percentage. Larval challenged sheep had 1.1% heavier full (p<0.001) and 0.6% heavier empty (p<0.001) small intestines, and 0.6% heavier full (p=0.005) and 0.3% heavier empty (p=0.026) large intestines compared to unchallenged sheep. Use of live weight change or other measures based on live weight (e.g. feed conversion efficiency) to assess the impact of nematode challenge in sheep may underestimate carcass productivity losses associated with larval challenge in sheep even at moderate levels of larval intake and without overt clinical signs of parasitism. Measurement of carcass weight and/or lean meat yield may better reflect the true economic effects of parasitism in sheep.
Publisher: Wiley
Date: 05-06-2022
DOI: 10.1111/AVJ.13173
Abstract: This case‐control study investigated associations between C ylobacter fetus or C ylobacter jejuni titre and reproductive outcomes in 22 flocks of Merino and non‐Merino maiden ewes aged 1–2 years old. C ylobacter titres were also determined for multiparous ewes aged 3 years or older on the same farms. C. fetus ‘positivity’ (titre ≥1:80) was detected for 12% (57/462 95% confidence interval [95% CI] 9.6 to 15.6) of maiden ewes and 31% (65/210 95% CI 25.0 to 37.4) of mature ewes. The odds for failing to rear a lamb in C. fetus ‐‘exposed’ maiden ewes (titre ≥1:10) was 2.01 times that of seronegative ewes (95% CI 1.09 to 3.77 P = 0.027), but there was no association between C. fetus‐ ‘positivity’ (titre ≥1:80) and failure to rise (OR 1.69 95% CI 0.77 to 3.76 P = 0.191). C. fetus abortions were confirmed with microbial culture in one maiden ewe flock. In this flock, C. fetus titres fluctuated and often waned by lamb marking, highlighting the value of necropsies during abortion investigations. C. jejuni‐ ‘positivity’ (titre ≥1:80) was detected for 44% (204/462 95% CI 39.7 to 48.7) maiden ewes, but odds of failing to rear were decreased for C. jejuni ‐‘positive’ ewes (OR 0.52 95% CI 0.32 to 0.83 P = 0.007). The association between C ylobacter serology and the reproductive outcome was inconsistent in these flocks. Serology should be considered in the context of other risk factors and used in conjunction with other strategies to investigate the impact of C ylobacter exposure on ewe reproductive performance such as monitoring for abortions and lamb necropsies to determine aetiological diagnosis, and vaccination trials.
Publisher: Elsevier BV
Date: 11-2015
Publisher: MDPI AG
Date: 18-02-2022
DOI: 10.3390/ANI12040513
Abstract: Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared to multiparous ewes was 58% (74 vs. 132% p 0.001), and this was attributable to a 50% difference in reproductive rate (109 vs. 159% p 0.001) and 16% difference in lamb survival to marking (67 vs. 83% p 0.001). The difference in marking rate for maiden Merino two-tooth ewes lambing at approximately 2 years-of-age compared to mature multiparous ewes was 22% (80 vs. 102% p 0.001) and this was attributable to a 24% difference in reproductive rate (108 vs. 132% p 0.001) and 3% difference for lamb survival (75 vs. 78% p 0.05). Positive correlations for reproduction traits (reproductive rate, lamb survival and marking rate) between maidens and multiparous ewes were observed for maiden Merino two-tooth ewes (p 0.001), but these correlations were weak or non-existent for non-Merino ewe lambs. Strategies to improve both reproductive rate and lamb survival can address the poorer and more variable reproductive performance of maiden ewes.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.VETPAR.2011.11.049
Abstract: As it has been 30 years since a new anthelmintic class was released, it is appropriate to review management practices aimed at slowing the development of anthelmintic resistance to all drug classes. Recommendations to delay anthelmintic resistance, provide refugia and the use of a simulation model were reviewed to find optimum treatment strategies that maintain nematode control. Simulated Australian conditions indicated that a common successful low-risk treatment program was a rapid rotation between a "triple-combination" product (benzimidazole+levamisole+abamectin) and a new high-efficacy drug (monepantel). Where Haemonchus contortus was a threat, moxidectin was required at critical times because of its persistent activity against this parasite. Leaving up to 4% of adult sheep untreated provided sufficient "refugia" for non-selected worms to reduce the risk of selecting for anthelmintic resistance without compromising nematode control. For a new anthelmintic, efficacy estimated by faecal egg count reduction (FECR) is likely to be at or close to 100%, however using current methods the 95% confidence limits (CL) for 100% are incorrectly determined as 100%. The fewer eggs counted pre-treatment, the more likely an estimate of 100% will occur, particularly if the true efficacy is >90%. A novel way to determine the lower-CL (LCL) for 100% efficacy is to reframe FECR as a binomial proportion, i.e. define: n and x as the total number of eggs counted (rather than eggs per gram of faeces) for all pre-treatment and post-treatment animals, respectively p the proportion of resistant eggs is p = x/n and percent efficacy is 100 ×(1-p) (assuming equal treatment group sizes and detection levels, pre- and post-treatment). The LCL is approximated from the cumulative inverse beta distribution by: 95%LCL=100 ×(1-(BETAINV(0.975, x+1, n-x+1))). This method is simpler than the current method, independent of the number of animals tested, and demonstrates that for 100% efficacy at least 37 eggs (not eggs per gram) need to be counted pre-treatment before the LCL can exceed 90%. When nematode aggregation is high, this method can be usefully applied to efficacy estimates lower than 100%, and in this case the 95% upper-CL (UCL) can be estimated by: 95% UCL = 100 ×(1((BETAINV(0.025, x+1, n-x+1))), with the LCL approximated as described above. A simulation study to estimate the precision and accuracy of this method found that the more conservative 99%CL was optimum in this case 0.975 and 0.025 are replaced by 0.995 and 0.005 to estimate the LCL and UCL, respectively.
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.VETPAR.2015.09.031
Abstract: This study aimed to establish whether sheep flock production losses due to nematode (worm) infections are typically greater in mature sheep selected for anthelmintic treatment at random compared to sheep selected for treatment based on low (poorer) body condition score (BCS). The study also examined the proportion of sheep in flocks that could be left untreated before production losses became evident, and projected worm egg pasture contamination. Sheep were monitored at two experimental sites in Western Australia (Mediterranean climate). Sheep were stratified for BCS, liveweight and faecal worm egg count (WEC) and allocated into treatment groups (treated or untreated), with equal numbers for each. Liveweight, BCS and WEC measurements were taken on 6 occasions at Farm A and 10 occasions at Farm B. Comparisons of sheep production (liveweight and BCS change) and pasture contamination potential (WEC) were conducted by generating "virtual flocks" of varying proportions sheep untreated (10%, 20%, 30%, 40%, and 50% untreated). For the comparison of the selection mode of sheep for treatment, the untreated sheep were either selected at random, or as the highest BCS animals at the commencement of observations. Univariate general linear models with least square difference post-hoc tests were used to examine differences between flocks for liveweight, BCS and WEC, and regression analysis was used to examine relationships between BCS and WEC, and liveweight and WEC. No difference in body weights was observed between flocks with varying proportions of ewes notionally left untreated at Farm B, and until more than 30% were left untreated at Farm A. There was no difference in BCS between flocks with varying proportions of ewes left untreated at either site. At no point were there differences in cumulative liveweight change or BCS between selection methods (BCS versus random) where the same proportion of sheep in virtual flocks were left untreated, suggesting that effort committed to in idual BCS assessment would be of no benefit under these circumstances except for identifying low BCS sheep at risk of falling below critical limits associated with health or welfare risks. No consistent relationship between WEC and BCS or bodyweight was observed, indicating that BCS selection would have no lesser or greater impact on worm pasture contamination compared to random selection. Summer treatments based on a random selection index (with a minimum BCS limit), with up to 30% of adult sheep untreated can be expected to delay the development of anthelmintic resistance, with minimal adverse effect on sheep health or production.
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.VETPAR.2011.05.050
Abstract: On two extensive sheep farms in southern Western Australia, 111 (Farm A) and 124 (Farm B) female crossbred lambs (2-6 weeks old) were randomly selected and in idually identified using ear tags (a numbered tag and radio-frequency tag) at marking. On five separate occasions, faecal s les were collected and live weight, body condition score (BCS), faecal consistency score (FCS), breech fleece faecal soiling score and faecal dry matter percentage (DM%) were recorded. Lamb hot carcase weight (HCW) and dressing percentage were measured at slaughter. Faecal s les were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and triosephosphate isomerise [tpi]) and C ylobacter jejuni (16S rRNA). Observation of Eimeria oocysts and faecal worm egg counts (WECs) were performed using a modified McMaster technique. The WECs were adjusted for FCS for analyses. Faecal s les were screened for patent strongylid infections using PCR (specifically ITS-2 nuclear ribosomal DNA for Teladorsagia circumcincta, Trichostrongylus spp. and Haemonchus contortus). Lambs positive for Cryptosporidium at least once had lighter HCWs by 1.25 kg (6.6%) (P=0.029) and 1.46 kg (9.7%) (P<0.001) compared to lambs never positive for Cryptosporidium for Farms A and B respectively. Similarly, dressing percentages were 1.7% (P=0.022) and 1.9% (P<0.001) lower in Cryptosporidium-positive lambs on Farms A and B respectively. Lambs positive for Giardia at least once had 0.69 kg (P<0.001) lighter HCWs and 1.7% (P<0.001) lower dressing percentages compared to lambs never positive for Giardia on Farm B only. Cryptosporidium-positive lambs at the second s ling were 4.72 (P=0.010) and 3.84 (P=0.002) times more likely to have non-pelleted faeces compared to Cryptosporidium-negative lambs for Farms A and B respectively. Breech fleece faecal soiling scores of Cryptosporidium-positive lambs were 3.36 (P=0.026) and 2.96 (P=0.047) times more likely to be moderate to severe (scores 3-5), compared to negative lambs at the second s ling for Farms A and B respectively. Live weight, growth rate and BCS were inconsistently associated with protozoa detection across different s lings and farms. Adjusted WEC was correlated positively with FCS and negatively with faecal DM%, differing between s ling occasions and farms. C ylobacter jejuni prevalence was very low (<1%). Adjusted WEC were not correlated with carcase attributes, growth rates or live weights. This study is the first to quantify productivity consequences of naturally acquired protozoa infections in lambs managed under extensive farming conditions.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2019
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.VETPAR.2014.10.031
Abstract: Sheep nematode control utilising refugia-based strategies have been shown to delay anthelmintic resistance, but the optimal indices to select in iduals to be left untreated under extensive sheep grazing conditions are not clear. This experiment tested the hypothesis that high body condition can indicate ability of mature sheep to better cope with worms and therefore remain untreated in a targeted treatment programme. Adult Merino ewes from flocks on two private farms located in south-west Western Australia (Farm A, n = 271, and Farm B, n = 258) were measured for body condition score (BCS), body weight and worm egg counts (WEC) on four occasions between May and December (pre-lambing, lamb marking, lamb weaning and post-weaning). Half of the ewes in each flock received anthelmintic treatments to suppress WEC over the experimental period and half remained untreated (unless critical limits were reached). Response to treatment was analysed in terms of BCS change and percentage live weight change. No effect of high or low initial WEC groups was shown for BCS response, and liveweight responses were inconsistent. A relatively greater BCS response to treatment was observed in ewes in low BCS pre-lambing compared to better-conditioned ewes on one farm where nutrition was sub-optimal and worm burdens were high. Sheep in low body condition pre-lambing were more than three times more likely to fall into a critically low BCS (<2.0) if left untreated. Recommendations can be made to treat ewes in lower BCS and leave a proportion of the higher body condition sheep untreated in a targeted selective treatment programme, to provide a population of non-resistant worms to delay the development of resistance.
No related grants have been discovered for Caroline Jacobson.