Publications by authors named "Mark A Stevenson"

65 Publications

Analysis of daily variation in the release of faecal eggs and coproantigen of Fasciola hepatica in naturally infected dairy cattle and the impact on diagnostic test sensitivity.

Vet Parasitol 2021 Jun 24;298:109504. Epub 2021 Jun 24.

Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Bundoora, Victoria, 3083, Australia. Electronic address:

The liver fluke, Fasciola hepatica (F. hepatica) is a widespread parasite infection in dairy cattle in Victoria, South-eastern Australia. Robust diagnosis of fluke infection is needed in dairy cattle to identify sub-clinical infections which often go unnoticed, causing significant production losses. We tested the coproantigen ELISA (cELISA) and the FlukeFinder faecal egg count kit® on naturally infected cows in a fluke endemic region of Victoria. The aim of the study was to investigate the variation in the release of coproantigens and eggs into faeces over a 5-day period, at the morning (AM) and afternoon (PM) milkings, and to assess the impact of the timing of faecal sample collection on diagnostic test sensitivity. Ten cows were enrolled into the study based on positive F. hepatica faecal egg counts (LFEC) and faecal samples from the ten cows were collected twice daily, at the 7-9 AM and 4-6 PM milking, for five consecutive days. At the conclusion of the sampling period, the cows were euthanized and F. hepatica burden determined at necropsy. A moderate negative correlation between cow age and cELISA optical density (OD) was observed using data from all samples (R -0.63; 95 % CI -0.68 to -0.57). Over the 5-day sampling period, we observed within-animal variation between days for both the cELISA OD (2.6-8.9 fold) and LFEC (5-16 fold), with more variation in values observed in the PM samples for both tests. The correlation with total fluke burden was higher in the AM sampling using both the cELISA and LFEC (R 0.64 and 0.78, respectively). The sensitivity was 100 % for the cELISA using various cut offs from the literature (0.014 OD, 0.030 OD, and 1.3 % or 1.6 % of the positive control). The sensitivity of the FlukeFinder kit® (based on 588 faecal samples and not accounting for lack of independence in the data) was 88 % (95 % CI 85 %-90 %). Seventy one false negatives were recorded from the 588 LFEC tests all of which were observed in the cows with fluke burdens <14 flukes; 42 of the 71 false negative LFECs occurred in one individual cow which had the lowest burden of nine flukes. In dairy cows, the cut-off for production losses due to fasciolosis is estimated at> 10 fluke. Both the cELISA and the LFEC identified all cows that had burdens equal to or greater than this cut-off. Five of the ten cows also exhibited relatively high paramphistome egg counts.
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http://dx.doi.org/10.1016/j.vetpar.2021.109504DOI Listing
June 2021

Antibiotic Prescription in Veterinary Consultations in Bhutan: A Retrospective Cross-Sectional Study.

Front Vet Sci 2021 28;8:641488. Epub 2021 May 28.

Department of Infectious Diseases, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia.

The veterinary prescription of antibiotics in low- and middle-income countries (LMIC) remains largely undocumented. In Bhutan, however, the national veterinary service keeps records of their activities and prescriptions, which offer an opportunity to establish a benchmark to assess the use of these agents in this and other LMIC. A cross-sectional retrospective study was designed and 2,266 handwritten veterinary records from 2017 were sampled from 23 animal health premises (AHPs) to estimate individual and an overall proportion of consultations that resulted in an antibiotic prescription. The frequency of antibiotic prescription per species, type of AHP, and according to WHO's AWaRe index and OIE list of priority antimicrobials were also explored. It was estimated that 31% (95% confidence interval: 29-33%; intracluster correlation: 0.03) of the veterinary consultations resulted in an antibiotic prescription. The incidence of antibiotic prescription was highest in consultations of poultry across AHP. Across species, were frequently treated with broad-spectrum antibiotics including sulfonamides, tetracyclines, trimethoprim + sulfa, and penicillin. Between 45% and 70% antibiotics prescribed correspond to AWaRe's and up to 25% to AWaRe's . Over 70% of antibiotics dispensed in veterinary consultations for any species correspond to the OIE's . Overall, the study demonstrated positive features of veterinary antimicrobial stewardship in Bhutan, given the conservative proportion of consultation that results in this type of prescription and the type of antibiotic prescribed. Although the veterinary service closely follows the Bhutanese Standard Treatment Guidelines, the prescription of antibiotics to key species should be closely monitored. Our study suggests that further improvements of antibiotic stewardship can be achieved through standardisation of antibiotic prescription to some species, a revision of the guidelines toward reducing the prescription of antibiotics of high relevance for human medicine, and by including details of clinical investigation, use of tests, and treatment outcomes in veterinary consultation records.
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http://dx.doi.org/10.3389/fvets.2021.641488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8194083PMC
May 2021

Structural anatomy and morphometric analyses of sacra in greyhounds.

Anat Histol Embryol 2021 Jul 9;50(4):716-725. Epub 2021 Jun 9.

Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Vic., Australia.

This study was conducted to provide structural and morphological data on the sacra of greyhounds. Descriptive quantitative investigation was carried out on 171 sacra of greyhound`s cadavers and then classified into standard and fused sacra based on the number of fused sacral vertebrae. The weight, length and width of sacrum of sacra were measured. Both standard (59%) and fused sacra (41%) were identified. The average length and width of the standard sacrum were found to be 46.14 ± 2.53 mm and 57.89 ± 3.54 mm, respectively. The sacral length was 1.61-mm longer in males (p < .01), and the sacral width was 0.46-mm shorter in males but not significant (p = .51). The average weight of a standard sacrum was 26.54 ± 4.55 g and was 1.18 g heavier in males but not statistically significant (p = .24). Results showed that one-kilogram increase in the body mass was associated with a 0.3 mm (p < .001) increase in sacral length, and a 0.54 mm (p < .001) increase in sacral width, respectively. The morphological data of the standard and fused sacra provided in this study might help the veterinary community to improve treatment and rehabilitation and help the trainer to design the right training protocol for racing greyhounds. In addition, the results of this study are a step to understand the sacrum's functions and how the greyhound's body functions and future studies are required to investigate the biological importance of these findings.
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http://dx.doi.org/10.1111/ahe.12677DOI Listing
July 2021

Variation in the seventh lumbar vertebra and the lumbosacral junction morphometry associated with the sacrocaudal fusion in greyhounds.

Anat Histol Embryol 2021 May 20;50(3):668-677. Epub 2021 Apr 20.

Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Vic., Australia.

The lumbosacral joint is where the 7th lumbar vertebra (L.7) articulates within the sacrum. It is a clinically important area in the dog because of its relatively large range of motion. The current study aims to determine the possible differences in the length of the L.7 vertebra and the angle of the lumbosacral junction among greyhounds of standard and those of fused sacra, and to determine the potential association of sex, body mass and type of fused sacrum (standard and fused) on the morphology of the L.7 vertebra and the angle of the lumbosacral junction. Radiographs of 55 greyhound cadavers were used for radiographing; all radiographic images were stored and measured using X-ray acquisition software, and then analysed using descriptive statistics, multiple linear regression and logistic regression. The results of this study showed a significant increase (p < .008) in the length of the L.7 vertebra and the angle of the lumbosacral junction (p < .028) in greyhounds with fused sacra comparing with those of standard sacra, but the L.6 length was not significant (p = .431). Differences have been found in the length of L.7 vertebra and the angle of the lumbosacral junction in greyhounds. It was found that in greyhounds, any variation in the sacrum's anatomical features may alter the structure of the surrounding anatomical structures such as the L.7 vertebra and lumbosacral junction.
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http://dx.doi.org/10.1111/ahe.12675DOI Listing
May 2021

Sample Size Estimation in Veterinary Epidemiologic Research.

Authors:
Mark A Stevenson

Front Vet Sci 2020 17;7:539573. Epub 2021 Feb 17.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia.

In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a study and details of the assumptions and methodologies used to derive sample size estimates are now a mandatory component of grant application processes by funding agencies. Studies with insufficient numbers of study subjects run the risk of failing to identify differences among treatment or exposure groups when differences do, in fact, exist. Selection of a number of study subjects greater than that actually required results in a wastage of time and resources. In contrast to human epidemiological research, individual study subjects in a veterinary setting are almost always aggregated into hierarchical groups and, for this reason, sample size estimates calculated using formulae that assume data independence are not appropriate. This paper provides an overview of the reasons researchers might need to calculate an appropriate sample size in veterinary epidemiology and a summary of sample size calculation methods. Two approaches are presented for dealing with lack of data independence when calculating sample sizes: (1) inflation of crude sample size estimates using a design effect; and (2) simulation-based methods. The advantage of simulation methods is that appropriate sample sizes can be estimated for complex study designs for which formula-based methods are not available. A description of the methodological approach for simulation is described and a worked example provided.
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http://dx.doi.org/10.3389/fvets.2020.539573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7925405PMC
February 2021

The Effect of Pet Insurance on Presurgical Euthanasia of Dogs With Gastric Dilatation-Volvulus: A Novel Approach to Quantifying Economic Euthanasia in Veterinary Emergency Medicine.

Front Vet Sci 2020 8;7:590615. Epub 2020 Dec 8.

Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia.

Euthanasia of companion animals in veterinary emergency medicine is a common cause of death. Euthanasia is economic when it is the consequence of the pet owner's inability to afford essential treatment while a viable medical alternative to euthanasia exists. Gastric dilatation-volvulus (GDV) is an acute life-threatening emergency condition of dogs; if left untreated, rapid death is highly likely. Surgical treatment leads to survival of around 80-90% of dogs; however, such treatment is costly. Therefore, pre-surgical euthanasia may be largely economically motivated. Having pet insurance, a financial instrument to reduce the burden of unforeseen veterinary medical costs on pet owners, would be expected to abolish the risk for pre-surgical economic euthanasia. We therefore aimed to determine whether pet insurance attenuates the risk of pre-surgical economic euthanasia in dogs with GDV. Non-referred dogs ( = 260) with GDV and known insurance status seen at 24 emergency clinics over a 2-year period were included. Relevant data (e.g., insurance status, age, comorbidities, outcome) were retrospectively extracted from a pet insurer's claim records (insured animals) or from electronic medical records of participating hospitals (non-insured animals). Forty-one percent of dogs (106 of 260 dogs) did not survive to hospital discharge; 82 (77%) of non-survivors died before surgery, all through euthanasia. The pre-surgical euthanasia rate was 10% in insured and 37% in non-insured dogs ( < 0.001). When adjusted for the effect of age, deposit size, comorbidities, and blood lactate concentration, the absence of insurance increased the odds of pre-surgical euthanasia by a factor of 7.4 (95% CI 2.0 to 37; = 0.002). Of dogs undergoing surgery, 86% survived to hospital discharge. Overall, 80% of insured animals and 53% of non-insured animals survived to hospital discharge ( < 0.001). Thus, insurance was associated with a marked decrease in risk of pre-surgical euthanasia indicating that the cause of pre-surgical euthanasia of dogs with GDV is predominantly economic in nature. The rate of pre-surgical euthanasia in dogs with GDV may emerge as a suitable marker to quantify economic decision making of pet owners and to measure the impact of financial interventions aimed at mitigating economic duress associated with cost of veterinary emergency care.
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http://dx.doi.org/10.3389/fvets.2020.590615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7752994PMC
December 2020

Descriptive analysis of Thoroughbred horses born in Victoria, Australia, in 2010; barriers to entering training and outcomes on exiting training and racing.

PLoS One 2020 28;15(10):e0241273. Epub 2020 Oct 28.

Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.

The reasons for Thoroughbred (TB) horses not entering training or exiting the racing industry, are of interest to regulators, welfare groups and the broader community. Speculation about the outcomes of these horses threatens the community acceptance, or social license, of the TB breeding and racing industries. A representative survey of the 2010 Victorian born TB foal crop was used to determine the outcomes and reasons for exit for horses that had not entered training, or had exited training and racing by eight years of age. Horses exported for racing or breeding (4%), or that were still actively racing (7%) at the start of the follow up period were excluded from the study. An online questionnaire was sent to breeders or trainers of 3,176 TB horses eligible for enrolment in the study. Of the 2,005 (63%) responses received, the two most frequent outcomes were that the horse had either been retired or rehomed (65%), or deceased (16%). For the 1,637 TB horses that had entered training, the majority of retirements were voluntary (59%), followed by involuntary retirements due to health disorders (28%). For TBs that did not have an industry record of entering training (n = 368), death (34%), or retirement or being rehomed (27%), were the most frequent barriers to entering training. The median age of retirement for TBs that raced was five (Q1 4; Q3 6) years regardless of sex, or whether their first race start was at two, three or four years of age. Relatively large numbers of horses voluntarily retiring at five-years of age suggests that industry-level, rather than individual horse-level factors are the predominant influences on racing career duration.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241273PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592779PMC
December 2020

Variation in GPS and accelerometer recorded velocity and stride parameters of galloping Thoroughbred horses.

Equine Vet J 2020 Oct 24. Epub 2020 Oct 24.

U-Vet Equine Centre, Melbourne Veterinary School, The University of Melbourne, Werribee, Vic., Australia.

Background: With each stride, galloping horses generate large skeletal loads which influence bone physiology, and may contribute to musculoskeletal injury. Horse speed and stride characteristics are related, but the usefulness of using horse speed and distance travelled as a proxy for stride characteristics is unknown.

Objectives: We aimed to determine stride characteristics, their variance and their relationship with speed in horses performing maximally.

Study Design: Retrospective cross-sectional analysis of archived data.

Methods: Stride characteristics obtained using GPS and inertial sensors in Thoroughbred horses were retrieved. Data per 200 m race segment ('sectionals') for horses competing in races (N = 25,259 race starts) were analysed to determine if speed predicted stride parameters. Multivariable mixed-effects linear regression models were fitted.

Results: Mean (±SD) stride length, stride count (number of strides per 200 m), duration and speed were 7.08 ± 0.39 m, 28.32 ± 1.56 strides/200 m, 0.43 ± 0.02 s/stride and 16.63 ± 1.04 m/s across all sectionals and starts. Speed and stride length decreased, and stride count increased with race progression (P < 0.001). Male sex, greater race distance, better finishing position and firmer track surfaces were associated with less strides per 200 m and longer stride durations.

Main Limitations: Lack of an independent party validation of the measurement system used in this study.

Conclusions: There was a substantial inter-horse variation in stride parameters, with speed predicting half or less of this variation. Speed alone does not fully explain stride characteristics in horses. Future studies aimed at investigating the impact of gait on bone biology and pathology would benefit from accounting for stride characteristics (eg length and duration).
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http://dx.doi.org/10.1111/evj.13370DOI Listing
October 2020

Differences in the clinical practice of small animal CPR before and after the release of the RECOVER guidelines: Results from two electronic surveys (2008 and 2017) in the United States and Canada.

J Vet Emerg Crit Care (San Antonio) 2020 Nov 25;30(6):615-631. Epub 2020 Sep 25.

Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia.

Objective: To assess whether the clinical approach to CPR has changed following the publication of the Reassessment Campaign on Veterinary Resuscitation (RECOVER) guidelines in 2012.

Design: Internet-based survey.

Setting: Academia and referral practice.

Subjects: Four hundred and ninety-one small animal veterinarians in clinical practice in the United States and Canada.

Interventions: An internet-based survey assessing the clinical approach to small animal CPR was circulated with the assistance of veterinary professional organizations on 2 separate occasions: prior to (2008) and following (2017) publication of the 2012 (RECOVER) guidelines. Survey questions identical to both surveys solicited details of clinician approaches to CPR preparedness, basic life support (BLS), and advanced life support (ALS). Respondents were grouped into level of expertise (board-certified specialists [BCS, n = 202] and general practitioners in emergency clinics [GPE, n = 289]), and year of response to the survey (2008, n = 171; 2017, n = 320).

Measurements And Main Results: Compliance with the RECOVER guidelines pertaining to CPR preparedness (P < 0.01), BLS (P < 0.01), and ALS P < 0.01) was consistently higher in respondents to the 2017 survey compared to those of the 2008 survey. Being a BCS was associated with significantly higher compliance with the RECOVER recommendations than GPE in the domains of preparedness (P = 0.02), BLS (P < 0.01), and ALS (P < 0.01). Increases in age of the respondent had a negative effect on compliance with the BLS guidelines (P < 0.01), while gender had no effect.

Conclusions: Compared to 2008, current practices in small animal CPR in the North American emergency and critical care community shifted toward those recommended in the RECOVER guidelines across all CPR domains. This supports the notion that uptake of the RECOVER guidelines among veterinary emergency or critical care clinicians was sufficient to lead to a change in the practice of CPR.
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http://dx.doi.org/10.1111/vec.13010DOI Listing
November 2020

Spatial relative risk and factors associated with porcine reproductive and respiratory syndrome outbreaks in United States breeding herds.

Prev Vet Med 2020 Oct 1;183:105128. Epub 2020 Sep 1.

Department of Veterinary Population Medicine, University of Minnesota, Minnesota, USA.

Details of incident cases of porcine reproductive and respiratory syndrome (PRRS) in United States breeding herds were obtained from the Morrison's Swine Health Monitoring Project. Herds were classified as cases if they reported an outbreak in a given season of the year and non-cases if they reported it in a season other than the case season or if they did not report a PRRS outbreak in any season. The geographic distribution of cases and non-cases was compared in each season of the year. The density of farms that had a PRRS outbreak during summer was higher in Southern Minnesota and Northwest-central Iowa compared to the density of the underlying population of non-case farms. This does not mean that PRRS outbreaks are more frequent during summer in absolute terms, but that there was a geographical clustering of herds breaking during summer in this area. Similar findings were observed in autumn. In addition, the density of farms reporting spring outbreaks was higher in the Southeast of the United States compared to that of the underlying population of non-case farms. A similar geographical clustering of PRRS outbreaks was observed during winter in the Southeast of the United States. Multivariable analyses, adjusting for the effect of known confounders, showed that the incidence rate of PRRS was significantly lower during winter and autumn during the porcine epidemic diarrhea (PED) epidemic years (2013-2014), compared to PRRS incidence rates observed during the winter and autumn of PED pre-epidemic years (2009-2012). After 2014, an increase in the incidence rate of PRRS was observed during winter and spring but not during autumn or summer. Pig dense areas were associated with a higher incidence rate throughout the year. However, this association tended to be stronger during the summer. Additionally, herds with ≥2500 sows had an increased incidence rate during all seasons except spring compared to those with <2500 sows. PRRS incidence was lower in year-round air-filtered herds compared to non-filtered herds throughout the year. We showed that not only the spatial risk of PRRS varies regionally according to the season of the year, but also that the effect of swine density, herd size and air filtering on PRRS incidence may also vary according to the season of the year. Further studies should investigate regional and seasonal drivers of disease. Breeding herds should maintain high biosecurity standards throughout the year.
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http://dx.doi.org/10.1016/j.prevetmed.2020.105128DOI Listing
October 2020

Transformation of organic matter in a Barents Sea sediment profile: coupled geochemical and microbiological processes.

Philos Trans A Math Phys Eng Sci 2020 Oct 31;378(2181):20200223. Epub 2020 Aug 31.

School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.

Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment-water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic-pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0-4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5-10.5 cm depth). Sulfate reducers dominate in the deeper (approx. 10.5-33 cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters (-alkanes, -alkanoic acids, -alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
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http://dx.doi.org/10.1098/rsta.2020.0223DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7481670PMC
October 2020

Does Arctic warming reduce preservation of organic matter in Barents Sea sediments?

Philos Trans A Math Phys Eng Sci 2020 Oct 31;378(2181):20190364. Epub 2020 Aug 31.

School of Earth and Environment, The University of Leeds, Leeds, UK.

Over the last few decades, the Barents Sea experienced substantial warming, an expansion of relatively warm Atlantic water and a reduction in sea ice cover. This environmental change forces the entire Barents Sea ecosystem to adapt and restructure and therefore changes in pelagic-benthic coupling, organic matter sedimentation and long-term carbon sequestration are expected. Here we combine new and existing organic and inorganic geochemical surface sediment data from the western Barents Sea and show a clear link between the modern ecosystem structure, sea ice cover and the organic carbon and CaCO contents in Barents Sea surface sediments. Furthermore, we discuss the sources of total and reactive iron phases and evaluate the spatial distribution of organic carbon bound to reactive iron. Consistent with a recent global estimate we find that on average 21.0 ± 8.3 per cent of the total organic carbon is associated to reactive iron (fOC-Fe) in Barents Sea surface sediments. The spatial distribution of fOC-Fe, however, seems to be unrelated to sea ice cover, Atlantic water inflow or proximity to land. Future Arctic warming might, therefore, neither increase nor decrease the burial rates of iron-associated organic carbon. However, our results also imply that ongoing sea ice reduction and the associated alteration of vertical carbon fluxes might cause accompanied shifts in the Barents Sea surface sedimentary organic carbon content, which might result in overall reduced carbon sequestration in the future. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
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http://dx.doi.org/10.1098/rsta.2019.0364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7481662PMC
October 2020

Benthic-pelagic coupling in the Barents Sea: an integrated data-model framework.

Philos Trans A Math Phys Eng Sci 2020 Oct 31;378(2181):20190359. Epub 2020 Aug 31.

BGeosys, Department of Earth and Environmental Sciences, CP 160/02, Université Libre de Bruxelles, 1050 Brussels, Belgium.

The Barents Sea is experiencing long-term climate-driven changes, e.g. modification in oceanographic conditions and extensive sea ice loss, which can lead to large, yet unquantified disruptions to ecosystem functioning. This key region hosts a large fraction of Arctic primary productivity. However, processes governing benthic and pelagic coupling are not mechanistically understood, limiting our ability to predict the impacts of future perturbations. We combine field observations with a reaction-transport model approach to quantify organic matter (OM) processing and disentangle its drivers. Sedimentary OM reactivity patterns show no gradients relative to sea ice extent, being mostly driven by seafloor spatial heterogeneity. Burial of high reactivity, marine-derived OM is evident at sites influenced by Atlantic Water (AW), whereas low reactivity material is linked to terrestrial inputs on the central shelf. Degradation rates are mainly driven by aerobic respiration (40-75%), being greater at sites where highly reactive material is buried. Similarly, ammonium and phosphate fluxes are greater at those sites. The present-day AW-dominated shelf might represent the future scenario for the entire Barents Sea. Our results represent a baseline systematic understanding of seafloor geochemistry, allowing us to anticipate changes that could be imposed on the pan-Arctic in the future if climate-driven perturbations persist. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
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http://dx.doi.org/10.1098/rsta.2019.0359DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7481668PMC
October 2020

Barriers to entering race training before 4 years of age for Thoroughbred horses born in the 2014 Australian foal crop.

PLoS One 2020 5;15(8):e0237003. Epub 2020 Aug 5.

Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.

Currently, there is a paucity of data on the barriers for Australian Thoroughbred horses transitioning from stud farm to racetrack. This paper reports the reasons why horses failed to enter race training and documents their exit destinations. Biographical records of Australian Thoroughbred horses born in 2014 were investigated to determine the number of horses that had not officially entered race training by the start of the 4-year old racing season (1 August 2018). Of the 13,677 foals born in 2014, 66% had commenced training and 51% had raced before the beginning of their 4-year-old season in Australia. A sampling frame based on the post code of the premises where foals were born and records from Racing Australia were used to select a geographically representative sample of the 2014 Australian Thoroughbred foal crop (n = 4,124). From the population eligible for sampling 1,275 horses that had not entered training were enrolled in the survey and their breeders were sent an online questionnaire with follow-up phone calls for those who had not responded. Of the 633 responses (50% of 1275) the most frequent outcomes for horses were: death (38%, n = 239), participation in the racing industry in their 4-year old racing season (24%, n = 154) and retirement (16%, n = 100) either as Australian Stud Book (ASB) bloodstock (n = 17), or as horses rehomed outside the Thoroughbred industry (n = 83). Illness or injury was the most frequent reason for horses not entering race training that were ASB bloodstock, rehomed or deceased. There was a loss of traceability at the point of sale with most horses sold at 1 year of age. This study provides important information on the reasons, alternative outcomes and gaps in traceability for horses not entering training prior to the 4-year-old racing season.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237003PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406052PMC
October 2020

Transmission network reconstruction for foot-and-mouth disease outbreaks incorporating farm-level covariates.

PLoS One 2020 15;15(7):e0235660. Epub 2020 Jul 15.

Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Ibaraki, Japan.

Transmission network modelling to infer 'who infected whom' in infectious disease outbreaks is a highly active area of research. Outbreaks of foot-and-mouth disease have been a key focus of transmission network models that integrate genomic and epidemiological data. The aim of this study was to extend Lau's systematic Bayesian inference framework to incorporate additional parameters representing predominant species and numbers of animals held on a farm. Lau's Bayesian Markov chain Monte Carlo algorithm was reformulated, verified and pseudo-validated on 100 simulated outbreaks populated with demographic data Japan and Australia. The modified model was then implemented on genomic and epidemiological data from the 2010 outbreak of foot-and-mouth disease in Japan, and outputs compared to those from the SCOTTI model implemented in BEAST2. The modified model achieved improvements in overall accuracy when tested on the simulated outbreaks. When implemented on the actual outbreak data from Japan, infected farms that held predominantly pigs were estimated to have five times the transmissibility of infected cattle farms and be 49% less susceptible. The farm-level incubation period was 1 day shorter than the latent period, the timing of the seeding of the outbreak in Japan was inferred, as were key linkages between clusters and features of farms involved in widespread dissemination of this outbreak. To improve accessibility the modified model has been implemented as the R package 'BORIS' for use in future outbreaks.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235660PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363093PMC
September 2020

A Participatory Investigation of Bovine Health and Production Issues in Pakistan.

Front Vet Sci 2020 6;7:248. Epub 2020 May 6.

Department of Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC, Australia.

Systems to record the frequency of animal health events in Pakistan are limited. A participatory approach was used to address gaps in farmers' knowledge and understanding of bovine health and production issues in five agroecological zones (AEZs) of Pakistan. Participatory tools, including simple ranking, pairwise ranking, constraint impact scoring, and constraint profiling were used in group discussions with farmers and animal health professionals (AHPs) in six districts of two provinces, Punjab and Sindh. The results of the ranking activities showed that foot-and-mouth disease (FMD), clinical mastitis, ticks, hemorrhagic septicemia, reproductive disorders, blackleg, and endoparasites were the most important bovine health and production constraints for small-scale dairy farmers. Constraint impact scoring showed that the participants perceived that: (1) milk production was severely affected by FMD and mastitis; (2) blackleg and parasitism led to poor growth rates and reduced meat production; (3) reproductive disorders and mastitis caused major economic losses (due to the high cost of treatment); and (4) blackleg and hemorrhagic septicemia were the leading causes of mortality in cattle and buffaloes. Although there was strong agreement in responses and constraint impact scores between farmers and AHPs, farmers were more concerned about health issues that cause high mortalities, whereas AHPs emphasized the importance of disorders with a high economic impact. Despite socioeconomic differences among AEZs, farmers' knowledge about bovine health and production constraints was similar. The findings from this study revealed that farmers had limited understanding of the risk factors and routes of transmission of various infectious diseases of bovines, which emphasizes the need to develop and implement tailored extension programs in Pakistan to control contagious diseases of animals and to improve the profitability of small-scale dairy farmers.
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http://dx.doi.org/10.3389/fvets.2020.00248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218055PMC
May 2020

Determination of the prevalence and intensity of Fasciola hepatica infection in dairy cattle from six irrigation regions of Victoria, South-eastern Australia, further identifying significant triclabendazole resistance on three properties.

Vet Parasitol 2020 Jan 31;277:109019. Epub 2019 Dec 31.

Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Bundoora Victoria 3083, Australia. Electronic address:

Fasciola hepatica (liver fluke) is a widespread parasite infection of livestock in Victoria, South-eastern Australia, where high rainfall and a mild climate is suitable for the main intermediate host Austropeplea tomentosa. The aims of this study were to quantify the prevalence and intensity of F. hepatica in dairy cattle in the irrigated dairy regions of Victoria and determine if triclabendazole resistance was present in infected herds. Cattle in 83 herds from the following six irrigation regions were tested for F. hepatica: Macalister Irrigation District (MID), Upper Murray (UM), Murray Valley (MV), Central Goulburn (CG), Torrumbarry (TIA) and Loddon Valley (LV). Twenty cattle from each herd were tested using the F. hepatica faecal egg count (FEC) as well as the coproantigen ELISA (cELISA). The mean individual animal true prevalence of F. hepatica across all regions was 39 % (95 % credible interval [CrI] 27%-51%) by FEC and 39 % (95 % CrI 27%-50%) by cELISA with the highest true prevalence (75-80 %) found in the MID. Our results show that 46 % of the herds that took part in this study were likely to experience fluke-associated production losses, based on observations that herd productivity is impaired when the true within-herd prevalence is > 25 %. Using the FEC and cELISA reduction tests, triclabendazole resistance was assessed on 3 herds in total (2 from the 83 in the study; and 1 separate herd that did not take part in the prevalence study) and resistance was confirmed in all 3 herds. This study has confirmed that F. hepatica is endemic in several dairy regions in Victoria: triclabendazole resistance may be contributing to the high prevalence in some herds. From our analysis, we estimate that the state-wide economic loss associated with fasciolosis is in the order of AUD 129 million (range AUD 38-193 million) per year or about AUD 50,000 (range AUD 15,000-75,000) per herd per year.
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http://dx.doi.org/10.1016/j.vetpar.2019.109019DOI Listing
January 2020

The Compliance of Current Small Animal CPR Practice With RECOVER Guidelines: An Internet-Based Survey.

Front Vet Sci 2019 11;6:181. Epub 2019 Jun 11.

Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia.

In 2012 the Reassessment Campaign on Veterinary Resuscitation (RECOVER) published evidence-based treatment recommendations for dogs and cats with cardiopulmonary arrest (CPA), to optimize the clinical practice of small animal CPR and positively impact outcomes. Six years after the release of these guidelines, we aimed to determine the compliance of small animal veterinary CPR practices with these RECOVER guidelines. To identify current CPR practices in clinically active small animal veterinarians and their awareness of the RECOVER guidelines, we conducted an internet-based survey. Survey invitations were disseminated internationally via veterinary professional organizations and their social media outlets. Questions explored respondent demographics, CPR preparedness, BLS and ALS techniques and awareness of RECOVER guidelines. Responding small animal veterinarians ( = 770) in clinical practice were grouped by level of expertise: board-certified specialists (BCS, = 216) and residents (RES, = 69) in anesthesia or emergency and critical care, practitioners in emergency (GPE, = 299) or general practice (GPG, = 186). Large disparities in preparedness measures, BLS and ALS techniques emerged among levels of expertise. Only 32% (95% CI: 29-36%) of respondents complied with BLS practice guidelines, varying from 49% (95% CI: 42-55%) of BCS to 15% (95% CI: 10-20%) of GPG. While incompliances in BCS, RES, and GPE were predominantly due to knowledge gaps, GPG compliance was further compromised by limitations in the resuscitation environment (e.g., defibrillator availability, team size). Those aware of RECOVER guidelines (100% of BCS and RES; 77% of GPE; 35% of GPG) were more likely to comply with recommended preparedness (OR = 2.4; 95% CI: 1.2-4.8), BLS (OR = 4.5; 95% CI: 2.4-9.1), and ALS techniques (OR = 7.8; 95% CI: 2.4-9.1) independent of age, gender, region of practice or level of expertise. We conclude that awareness of RECOVER guidelines is high in specialists and residents, but incomplete among general practitioners. This awareness positively influenced compliance with CPR guidelines, but CPR practices continue to be variable and largely not in agreement with guidelines. A widely accessible educational strategy is required to broadly improve compliance with best practices in small animal CPR.
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http://dx.doi.org/10.3389/fvets.2019.00181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6581025PMC
June 2019

Reconstructing a transmission network and identifying risk factors of secondary transmissions in the 2010 foot-and-mouth disease outbreak in Japan.

Transbound Emerg Dis 2019 Sep 11;66(5):2074-2086. Epub 2019 Jun 11.

Viral Disease and Epidemiology Research Division, National Institute of Animal Health, National Agriculture Research Organization, Tsukuba, Japan.

Research aimed at understanding transmission networks, representing a network of "who infected whom" for an infectious disease outbreak, have been actively conducted in recent years. Transmission network models incorporating epidemiological and genetic data are valuable for elucidating disease transmission pathways. In this study, we reconstructed the transmission network of the foot-and-mouth disease (FMD) epidemic in Japan in 2010, and explored farm-level risk factors associated with increased risk of secondary transmission. A published, systematic Bayesian transmission network model was applied to epidemiological data of 292 infected farms and whole genome sequence data of 104 of the infected farms. This model can make inferences for known infected farms even lacking genetic data. After estimating the consensus network, the accuracy of the network was examined by comparison with epidemiological data. Then, risk factors inferred to have been sources of secondary transmission were explored using zero-inflated Poisson regression model. As far as we are aware, this study represents the largest FMD outbreak transmission network to be published by such means combining epidemiological and genetic data. The consensus network reasonably generated the epidemiological links, which were estimated from the actual epidemiological investigation. Among 292 farms, 101 farms (35%) were inferred to have been the sources of secondary transmission, and amongst these farms, the median number of secondary cases was 2 (min:1-max:18) farms. The farm-type (small and large -sized pig farms), the number of days from onset to notification, and the number of susceptible farms within a 1-km radius were significantly associated with secondary transmission. Transmission network modelling enabled inference of the connections between infected farms during the FMD epidemic and identified important factors for controlling the risk of secondary transmission. This study demonstrated that the predominant susceptible species held on a farm, farm size, and animal density were associated with increased onwards transmission.
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http://dx.doi.org/10.1111/tbed.13256DOI Listing
September 2019

A systematic study towards evolutionary and epidemiological dynamics of currently predominant H5 highly pathogenic avian influenza viruses in Vietnam.

Sci Rep 2019 05 22;9(1):7723. Epub 2019 May 22.

Laboratory of Microbiology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, 060-0818, Japan.

This study aimed to elucidate virus, host and environmental dynamics of Vietnamese H5 highly pathogenic avian influenza viruses (HPAIVs) during 2014-2017. Epidemiologically, H5 HPAIVs were frequently detected in apparently healthy domestic and Muscovy ducks and therefore these are preferred species for H5 HPAIV detection in active surveillance. Virologically, clade 2.3.2.1c and 2.3.4.4 H5 HPAIVs were predominant and exhibited distinct phylogeographic evolution. Clade 2.3.2.1c viruses clustered phylogenetically in North, Central and South regions, whilst clade 2.3.4.4 viruses only detected in North and Central regions formed small groups. These viruses underwent diverse reassortment with existence of at least 12 genotypes and retained typical avian-specific motifs. These H5 HPAIVs exhibited large antigenic distance from progenitor viruses and commercial vaccines currently used in poultry. Bayesian phylodynamic analysis inferred that clade 2.3.2.1c viruses detected during 2014-2017 were likely descended from homologous clade viruses imported to Vietnam previously and/or preexisting Chinese viruses during 2012-2013. Vietnamese clade 2.3.4.4 viruses closely shared genetic traits with contemporary foreign spillovers, suggesting that there existed multiple transboundary virus dispersals to Vietnam. This study provides insights into the evolution of Vietnamese H5 HPAIVs and highlights the necessity of strengthening control measures such as, preventive surveillance and poultry vaccination.
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http://dx.doi.org/10.1038/s41598-019-42638-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531488PMC
May 2019

Spatiotemporal and risk analysis of H5 highly pathogenic avian influenza in Vietnam, 2014-2017.

Prev Vet Med 2020 May 22;178:104678. Epub 2019 Apr 22.

Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan; Global Institution for Collaborative Research and Education, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan. Electronic address:

The aim of this study was to describe the spatiotemporal distribution of H5 HPAI outbreak reports for the period 2014-2017 and to identify factors associated with H5 HPAI outbreak reports. Throughout the study period, a total of 139 outbreaks of H5 HPAI in poultry were reported, due to either H5N1 (96 outbreaks) or H5N6 (43 outbreaks) subtype viruses. H5N1 HPAI outbreaks occurred in all areas of Vietnam while H5N6 HPAI outbreaks were only reported in the northern and central provinces. We counted the number of H5N1 and H5N6 outbreak report-positive districts per province over the four-year study period and calculated the provincial-level standardized morbidity ratio for H5N1 and H5N6 outbreak reports as the observed number of positive districts divided by the expected number. A mixed-effects, zero-inflated Poisson regression model was developed to identify risk factors for outbreak reports of each H5N1 and H5N6 subtype virus. Spatially correlated and uncorrelated random effects terms were included in this model to identify areas of the country where outbreak reports occurred after known risk factors had been accounted-for. The presence of an outbreak report in a province in the previous 6-12 months increased the provincial level H5N1 outbreak report risk by a factor of 2.42 (95% Bayesian credible interval [CrI] 1.27-4.60) while 1000 bird increases in the density of chickens decreased provincial level H5N6 outbreak report risk by a factor of 0.65 (95% CrI 0.38 to 0.97). We document distinctly different patterns in the spatial and temporal distribution of H5N1 and H5N6 outbreak reports. Most of the variation in H5N1 report risk was accounted-for by the fixed effects included in the zero-inflated Poisson model. In contrast, the amount of unaccounted-for risk in the H5N6 model was substantially greater than the H5N1 model. For H5N6 we recommend that targeted investigations should be carried out in provinces with relatively large spatially correlated random effect terms to identify likely determinants of disease. Similarly, investigations should be carried out in provinces with relatively low spatially correlated random effect terms to identify protective factors for disease and/or reasons for failure to report.
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http://dx.doi.org/10.1016/j.prevetmed.2019.04.007DOI Listing
May 2020

Spatial Analysis of a Cat-Borne Disease Reveals That Soil pH and Clay Content Are Risk Factors for Sarcocystosis in Sheep.

Front Vet Sci 2019 24;6:127. Epub 2019 Apr 24.

School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia.

Cat-borne parasites and their associated diseases have substantial impacts on human, livestock, and wildlife health worldwide. Despite this, large and detailed datasets that allow researchers to study broad-scale trends in the ecology of cat-borne diseases are either difficult to obtain or non-existent. One condition that is easily detected at slaughter is macroscopic sarcocystosis, a cat-borne parasitosis of sheep (). We conducted a cross-sectional study to describe the geographic distribution of sarcocystosis in sheep throughout South Australia and investigate ecosystem characteristics associated with the presence of disease. Data were obtained from two slaughterhouses which processed 3,865,608 sheep from 4,204 farms across 385,468 km of South Australia's land mass for the period 2007-2017. A Poisson point process model was developed to quantify environmental characteristics associated with higher densities of sarcocystosis-positive farms. Sarcocystosis was highly clustered on a large island off of the Australian coast and the density of sarcocystosis-positive farms increased in areas of low soil pH (intensity ratio: 0.86, 95% CI: 0.78, 0.95) and high clay content. We hypothesize that region was confounded by, and predominately acted as a proxy for, cat density. Our results have broader implications regarding the health, welfare, economic, and conservation impacts of other cat-borne parasitosis, such as toxoplasmosis.
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http://dx.doi.org/10.3389/fvets.2019.00127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491573PMC
April 2019

Reconstructing foot-and-mouth disease outbreaks: a methods comparison of transmission network models.

Sci Rep 2019 03 18;9(1):4809. Epub 2019 Mar 18.

Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia.

A number of transmission network models are available that combine genomic and epidemiological data to reconstruct networks of who infected whom during infectious disease outbreaks. For such models to reliably inform decision-making they must be transparently validated, robust, and capable of producing accurate predictions within the short data collection and inference timeframes typical of outbreak responses. A lack of transparent multi-model comparisons reduces confidence in the accuracy of transmission network model outputs, negatively impacting on their more widespread use as decision-support tools. We undertook a formal comparison of the performance of nine published transmission network models based on a set of foot-and-mouth disease outbreaks simulated in a previously free country, with corresponding simulated phylogenies and genomic samples from animals on infected premises. Of the transmission network models tested, Lau's systematic Bayesian integration framework was found to be the most accurate for inferring the transmission network and timing of exposures, correctly identifying the source of 73% of the infected premises (with 91% accuracy for sources with model support >0.80). The Structured COalescent Transmission Tree Inference provided the most accurate inference of molecular clock rates. This validation study points to which models might be reliably used to reconstruct similar future outbreaks and how to interpret the outputs to inform control. Further research could involve extending the best-performing models to explicitly represent within-host diversity so they can handle next-generation sequencing data, incorporating additional animal and farm-level covariates and combining predictions using Ensemble methods and other approaches.
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http://dx.doi.org/10.1038/s41598-019-41103-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6423326PMC
March 2019

Epidemiology of gastrointestinal nematodes of alpacas in Australia: II. A longitudinal study.

Parasitol Res 2019 Mar 9;118(3):901-911. Epub 2019 Feb 9.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.

We conducted a longitudinal survey on 13 alpaca farms in four climatic zones of Australia to understand the epidemiology of gastrointestinal nematodes (GINs) of alpacas. A total of 1688 fresh faecal samples were collected from both sexes of alpacas from May 2015 to April 2016 and processed for faecal egg counts (FEC) and molecular identification of eggs using the multiplexed-tandem PCR assay. Based on egg morphology, the overall prevalence of GINs was 61% while that for strongyles was 53%. The overall mean FEC was 168 eggs per gram (EPG) of faeces, with the highest count of 15,540 EPG. Weaners had the highest prevalence (73%) and mean FEC (295 EPG) of GINs followed by tuis, crias and adults. Alpacas in the winter rainfall zone had the highest prevalence (68%) as well as FEC (266 EPG) followed by Mediterranean-type, non-seasonal and summer rainfall zones. Trichostrongylus spp. (83%, 89/107), Haemonchus spp. (71%, 76/107) and Camelostrongylus mentulatus (63%, 67/107) were the three most common GINs of alpacas across all climatic zones. The mixed-effects zero-inflated negative binomial regression model used in this study showed that it could help to design parasite control interventions targeted at both the herd level and the individual alpaca level. The findings of this study showed that the epidemiology of GINs of alpacas is very similar to those of cattle and sheep, and careful attention should be paid when designing control strategies for domestic ruminants co-grazing with alpacas.
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http://dx.doi.org/10.1007/s00436-019-06236-7DOI Listing
March 2019

Epidemiology of gastrointestinal nematodes of alpacas in Australia: I. A cross-sectional study.

Parasitol Res 2019 Mar 4;118(3):891-900. Epub 2019 Feb 4.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia.

This study involved a national cross-sectional survey of gastrointestinal nematodes (GINs) of alpacas in Australia. A total of 1545 fresh faecal samples were collected from both sexes of alpacas and processed for faecal egg counts (FEC) and molecular identification of nematodes using the multiplexed tandem PCR assay. Based on egg morphology, the overall prevalence of GINs was 66% while that for strongyles was 59%. The overall mean FEC was 276 eggs per gram (EPG) of faeces, with the highest count of 17,415 EPG. Male alpacas had a higher prevalence (68%, 334/490) as well as mean FEC (328 ± 60 EPG) of GINs than females (63%, 602/954; 227 ± 26, respectively). Weaners had the highest prevalence (80%) whereas tuis had the highest FEC (402 EPG) of nematodes. The highest prevalence (77%, 293/383) and FEC (630 EPG) of GINs were observed in the summer rainfall zone followed by the Mediterranean-type rainfall, non-seasonal rainfall and winter rainfall zones. The characterisation of nematode DNA isolated from faeces revealed the occurrence of seven different GINs, including Camelostrongylus mentulatus, Cooperia spp., Haemonchus spp., Oesophagostomum spp., Ostertagia ostertagi, Teladorsagia circumcincta and Trichostrongylus spp. Besides, Nematodirus spp. and Trichuris spp. were also found during FECs. The prevalence of Haemonchus spp. was highest in the summer rainfall zone while that of C. mentulatus was highest in the Mediterranean-type rainfall, non-seasonal rainfall and winter rainfall zones. The findings of this study revealed that alpacas harbour many of the same nematodes as sheep and cattle.
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http://dx.doi.org/10.1007/s00436-019-06235-8DOI Listing
March 2019

An assessment of worm control practices used by alpaca farmers in Australia.

Vet Parasitol 2019 Jan 21;265:91-100. Epub 2018 Dec 21.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria 3030, Australia. Electronic address:

This study aimed to assess current worm control practices used by Australian alpaca farmers with an online questionnaire survey. The questionnaire contained questions about farm demography and general husbandry practices, farmers' knowledge about gastrointestinal nematodes (GINs) and their importance, the use of worm control strategies and anthelmintics, and grazing management. A link for the questionnaire survey was sent to all (n = 954) registered members of the Australian Alpaca Association in July 2015. The response rate for the questionnaire was 25% (239/954). The majority of respondents were from small (≤ 50 alpacas; 64%, 153/239) followed by medium (50-100 alpacas; 24%, 57/239) and large (>100 alpacas; 12%, 29/239) farms. Findings revealed that the majority of respondents kept Huacaya alpacas to produce high-quality fibre and alpacas were usually kept with other domestic ruminants (e.g. cattle and sheep). Although half of alpaca farmers (114/220) perceived that GINs were an important health problem of alpacas, with Haemonchus spp. being the most common nematode, the majority of them (174/220) used anthelmintics for nematode control. Macrocyclic lactones, a commercial combination of four anthelmintics (abamectin, albendazole, closantel and levamisole) and monepantel were the three most commonly used dewormers by Australian alpaca farmers. Although a significant proportion (166/213) of respondents used a quarantine drench for alpacas, very few respondents were aware of strategic deworming and the issue of anthelmintic resistance. Alpaca farmers mostly used anthelmintics at the dose rate recommended for sheep (47%, 79/167) and cattle (9%, 15/167), though some used 1.5 (31%, 51/167) and 2 (13%, 22/167) times the dose rate recommended for sheep. The majority of small herds used anthelmintics at the dose rate recommended for sheep and cattle while medium and large herds used anthelmintics at 1.5 to 2 times the dose rate recommended for sheep. This study provides invaluable insights into the demography of alpaca farms in Australia, husbandry practices used by alpaca farmers and their knowledge about worms and their control, thereby paving the way for developing guidelines for the control of GINs of alpacas.
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http://dx.doi.org/10.1016/j.vetpar.2018.12.006DOI Listing
January 2019

The prevalence of Coxiella burnetii shedding in dairy goats at the time of parturition in an endemically infected enterprise and associated milk yield losses.

BMC Vet Res 2018 Nov 20;14(1):353. Epub 2018 Nov 20.

Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Corner Park Drive and Flemington Road, Parkville Victoria, 3010, Australia.

Background: This was a panel study of the prevalence of C. burnetii infection in does in an endemic dairy goat enterprise in Victoria, Australia. Our first objective was to determine the prevalence of does shedding C. burnetii at the time of parturition and to quantify the concentration of genome equivalents (GE) present in each C. burnetii positive sample. Our second objective was to determine the proportion of positive does that were persistent shedders. Our final objective was to quantify the association between C. burnetii qPCR status at the time of kidding and daily milk volumes produced during the subsequent lactation.

Results: Vaginal swabs (n= 490) were collected from does at the time of kidding and analysed using a quantitative polymerase chain reaction (qPCR) assay. Shedding of C. burnetii was detected in 15% (95% CI: 12% to 18%) of the sampled does. Does were classified as qPCR-negative, qPCR-positive low and qPCR-positive high based on the estimated concentration of GE from the qPCR. Persistent shedding at relatively low concentrations was detected in 20% (95% CI: 10% to35%) of shedding does sampled again at their subsequent parturition. After controlling for possible confounders and adjusting for variation in daily milk yields at the individual doe level, daily milk yields for qPCR-positive high does were reduced by 17% (95% CI: 3% to 32%) compared to qPCR-negative does (p= 0.02).

Conclusions: Shedding concentrations of C. burnetii were highly skewed, with a relatively small group of does shedding relatively high quantities of C. burnetii. Further, high shedding does had reduced milk yields compared to qPCR-negative does. Early detection and culling of high shedding does would result in increased farm profitability and reduce the risk of Q fever transmission.
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http://dx.doi.org/10.1186/s12917-018-1667-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6245909PMC
November 2018

Anthelmintic resistance in gastrointestinal nematodes of alpacas (Vicugna pacos) in Australia.

Parasit Vectors 2018 Jul 4;11(1):388. Epub 2018 Jul 4.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria, 3030, Australia.

Background: Gastrointestinal nematodes (GINs) can cause significant economic losses in alpacas due to lowered production of fibre and meat. Although no anthelmintics are registered for use in alpacas, various classes of anthelmintics are frequently used to control parasitic gastroenteritis in alpacas in Australia and other countries. Very little is known about the current worm control practices as well as the efficacy of anthelmintics used against common GINs of alpacas. This study aimed to assess the existing worm control practices used by Australian alpaca farmers and to quantify the efficacy of commonly used anthelmintics against GINs of alpacas.

Methods: An online questionnaire survey was conducted to assess current worm control practices on 97 Australian alpaca farms, with an emphasis on the use of anthelmintics. Of this group of 97 alpaca farms, 20 were selected to assess the efficacy of eight anthelmintics and/or their combinations (closantel, fenbendazole ivermectin, monepantel, moxidectin and a combination of levamisole, closantel, albendazole, abamectin) using the faecal egg count reduction test (FECRT). A multiplexed-tandem PCR (MT-PCR) was used to identify the prevalent nematode genera/species.

Results: The response rate for the questionnaire was 94% (91/97). Almost half of the respondents kept alpacas with sheep and cattle, and 26% of respondents allowed alpacas to co-graze with these ruminants. Although only 63% respondents perceived worms to be an important health concern for alpacas, the majority of respondents (89%) used anthelmintics to control GINs of alpacas. The commonly used anthelmintics were macrocyclic lactones, monepantel, benzimidazoles, levamisole, closantel and their combinations, and they were typically administered at the dose rate recommended for sheep. The FECRT results showed that a combination of levamisole, closantel, albendazole and abamectin was the most effective dewormer followed by single drugs, including monepantel, moxidectin, closantel, fenbendazole and ivermectin. Haemonchus spp. were the most commonly resistant nematodes followed by Trichostrongylus spp., Camelostrongylus mentulatus, Ostertagia ostertagi and Cooperia spp.

Conclusions: This is the first study aimed at assessing worm control practices and efficacy of commonly used anthelmintics in alpacas in Australia. Our findings document the extent of anthelmintics resistance on Australian alpaca farms and identify those anthelmintics that are still effective against GINs of alpacas.
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http://dx.doi.org/10.1186/s13071-018-2949-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6031175PMC
July 2018

Comparison of McMaster and FECPAK methods for counting nematode eggs in the faeces of alpacas.

Parasit Vectors 2018 05 2;11(1):278. Epub 2018 May 2.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Werribee, Victoria, 3030, Australia.

This study aimed to compare the FECPAK and the McMaster techniques for counting of gastrointestinal nematode eggs in the faeces of alpacas using two floatation solutions (saturated sodium chloride and sucrose solutions). Faecal eggs counts from both techniques were compared using the Lin's concordance correlation coefficient and Bland and Altman statistics. Results showed moderate to good agreement between the two methods, with better agreement achieved when saturated sugar is used as a floatation fluid, particularly when faecal egg counts are less than 1000 eggs per gram of faeces. To the best of our knowledge this is the first study to assess agreement of measurements between McMaster and FECPAK methods for estimating faecal eggs in South American camelids.
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http://dx.doi.org/10.1186/s13071-018-2861-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5930814PMC
May 2018

Subchondral bone morphology in the metacarpus of racehorses in training changes with distance from the articular surface but not with age.

J Anat 2018 06 15;232(6):919-930. Epub 2018 Feb 15.

Equine Centre, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Vic., Australia.

The repetitive large loads generated during high-speed training and racing commonly cause subchondral bone injuries in the metacarpal condyles of racehorses. Adaptive bone modelling leads to focal sclerosis at the site of highest loading in the palmar aspect of the metacarpal condyles. Information on whether and how adaptive modelling of subchondral bone changes during the career of a racehorse is sparse. The aim of this cross-sectional study was to describe the changes in subchondral bone micromorphology in the area of highest loading in the palmar aspect of the metacarpal condyle in thoroughbred racehorses as a function of age and training. Bone morphology parameters derived from micro-CT images were evaluated using principal component analysis and mixed-effects linear regression models. The largest differences in micromorphology were observed in untrained horses between the age of 16 and 20 months. Age and duration of a training period had no influence on tissue mineral density, bone volume fraction or number and area of closed pores to a depth of 5.1 mm from the articular surface in 2- to 4-year-old racehorses in training. Horses with subchondral bone injuries had more pores in cross-section compared with horses without subchondral bone injuries. Differences in bone volume fraction were due to the volume of less mineralised bone. Tissue mineral density increased and bone volume fraction decreased with increasing distance from the articular surface up to 5.1 mm from the articular surface. Further research is required to elucidate the biomechanical and pathophysiological consequences of these gradients of micromorphological parameters in the subchondral bone.
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http://dx.doi.org/10.1111/joa.12794DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5979622PMC
June 2018
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