Search

Some injuries to broilers occur during rearing, but most injuries occur during handling before slaughter. Records provided by a processing plant for loads transported over a 19 mo period during 2009 and 2010 were examined. The median percentage of wing injuries per load was 5.7%, whereas injuries to the legs, breast, or shoulders were all less than 1% per load. Risk factors for wing injuries were examined by considering the data from each load by handling event (i.e., loads originating from the same producer on the same date). A multilevel model with three levels, producer (n = 86), handling event (n = 1694), and load (n = 4219), was fitted. The final model included weight, sex, season, catching team, time of day at which loading began, speed of loading, and an interaction between speed of loading and time of day. Factors that reduced the risk of wing injuries were loading lighter birds, loads containing only cockerels, and loading in the fall. The predicted percentage of wing injuries was relatively constant for slower loading speeds, but it was increased significantly when faster loading speeds were adopted during daytime (0700–1700). Identification of these risk factors can be used to adjust loading practices.

Co-cultivation has been used as a promising tool to turn on or up-regulate cryptic biosynthetic pathways for microbial natural product discovery. Recently, a modified culturing strategy similar to co-cultivation was investigated, where heat-killed inducer cultures were supplemented to the culture medium of producer fermentations to induce cryptic pathways. In the present study, the repeatability and effectiveness of both methods in turning on cryptic biosynthetic pathways were unbiasedly assessed using UHPLC-HRESIMS-based metabolomics analysis. Both induction methods had good repeatability, and they resulted in very different induced metabolites from the tested producers. Co-cultivation generated more induced mass features than the heat-killed inducer cultures, while both methods resulted in the induction of mass features not observed using the other induction method. As examples, pathways leading to two new natural products, N-carbamoyl-2-hydroxy-3-methoxybenzamide (1) and carbazoquinocin G (5), were induced and up-regulated through co-culturing a producer Streptomyces sp. RKND-216 with inducers Alteromonas sp. RKMC-009 and M. smegmatis ATCC 120515, respectively.

The objective of the study was to compare statistical methods for the analysis of binary repeated measures data with an additional hierarchical level. Random effects true models with autocorrelated ($\rho=1$, 0.9 or 0.5) subject random effects were used in this simulation study. The settings of the simulation were chosen to reflect a real veterinary somatic cell count dataset, except that the within--subject time series were balanced, complete and of fixed length (4 or 8 time points). Four fixed effects parameters were studied: binary predictors at the subject and cluster levels, respectively, a linear time effect, and the intercept. The following marginal and random effects statistical procedures were considered: ordinary logistic regression (OLR), alternating logistic regression (ALR), generalized estimating equations (GEE), marginal quasi-likelihood (MQL), penalized quasi-likelihood (PQL), pseudo likelihood (REPL), maximum likelihood (ML) estimation and Bayesian Markov chain Monte Carlo (MCMC). The performance of these estimation procedures was compared specifically for the four fixed parameters as well as variance and correlation parameters. The findings of this study indicate that in data generated by random intercept models ($\rho=1$), the ML and MCMC procedures performed well and had fairly similar estimation errors. The PQL regression estimates were attenuated while the variance estimates were less accurate than ML and MCMC, but the direction of the bias depended on whether binomial or extra-binomial dispersion was assumed. In datasets with autocorrelation ($\rho

Objective The aim of this study was to determine the relationship between milk urea nitrogen (MUN) and reproductive performance in dairy cows in western Thailand. Design All cows calving from November 2014 to April 2015 were included in the study, a total of 486 cows from 47 farms. Each cow had milk constituents and MUN tested monthly up to confirmed conception or until the 8th month after parturition. Each farm had a dietary assessment completed. Cox proportional hazard models with shared frailty were used to determine associations of conception rate. Results Cows became pregnant increasingly quickly over time, except during 100-150 days of lactation. A change in MUN from 12.5 to 13.5 mg/dL on the closet day to breeding was associated with a 5% decrease in conception. Milk protein was negatively associated with hazard of conception, whereas milk lactose and dietary protein:energy ratio had positive associations with conception rate. Breeding season was also significant; the highest conception rate was observed in cows inseminated during winter, whereas insemination during the humid rainy season resulted in the lowest conception rates. The farm random effect in the model was strongly significant. Conclusion Detrimental effects of higher MUN on rate of conception were identified. The rate of conception was positively associated with protein:energy ratio in the study. Therefore, good nutritional management leading to positive energy balance should benefit conception rates.

OBJECTIVE To investigate the effects of dexmedetomidine (DXM) and its subsequent reversal with atipamezole (APM) on the echocardiogram and circulating concentrations of cardiac biomarkers in cats. ANIMALS 14 healthy cats. PROCEDURES Cats underwent echocardiography and measurements of circulating cTn-I and NT-proBNP concentrations before (PRE) and during (INTRA) DXM sedation (40 µg/kg IM) and 2 to 4 (2H POST) and 24 (24H POST) hours after reversal with APM. RESULTS Administering DXM significantly decreased heart rate, right ventricular and left ventricular (LV) outflow tract velocities, and M-mode–derived LV free-wall thickness; increased LV end systolic diameter and volume; and caused valvar regurgitation. While sedative effects resolved within 25 minutes of APM reversal, the evolution of echocardiographic changes was mixed: LV ejection fraction and mitral valvar regurgitation score were different at 2H POST than at both INTRA and PRE (partial return toward baseline), LV end-diastolic volume was different PRE to INTRA and INTRA to 2H POST but not different PRE to 2H POST (full return toward baseline), and M-mode–derived LV free-wall thickness was significantly different from PRE to INTRA and PRE to 2H POST (no return toward baseline). Serum cTn-I and plasma NT-proBNP concentrations increased significantly with DXM, which remained significant 2H POST. CLINICAL RELEVANCE Administration of DXM and APM reversal produced changes in echocardiographic results and in circulating cTn-I and NT-proBNP concentrations. Understanding these changes could help veterinarians differentiate drug effects from cardiac disease.

Introduction:The proliferation of unmanned aerial vehicle (UAV) technology has the potential to change the situational awareness of medical incident commanders’ (ICs’) scene assessment of mass gatherings. Mass gatherings occur frequently and the potential for injury at these events is considered higher than the general population. These events have generated mass-casualty incidents (MCIs) in the past. The aim of this study was to compare UAV technology to standard practice (SP) in scene assessment using paramedic students during a mass-gathering event (MGE).Methods:This study was conducted in two phases. Phase One consisted of validation of the videos and accompanying data collection tool. Phase One was completed by 11 experienced paramedics from a provincial Emergency Medical Services (EMS) service. Phase Two was a randomized comparison with 47 paramedic students from the Holland College Paramedicine Program (Charlottetown, Prince Edward Island, Canada) of the two scene assessment systems. For Phase Two, the paramedic students were randomized into a UAV or a SP group. The data collection tool consisted of two board categories: primary importance with 20 variables and secondary importance with 25 variables. After a brief narrative, participants were either shown UAV footage or the ground footage depending on their study group. After completion of the videos, study participants completed the data collection tool.Results:The Phase One validation showed good consensus in answers to most questions (average 79%; range 55%-100%). For Phase Two, a Fisher’s exact test was used to compare each variable from the UAV and SP groups using a P value of .05. Phase Two demonstrated a significant difference between the SP and UAV groups in four of 20 primary variables. Additionally, significant differences were found for seven out of 25 secondary variables.Conclusion:This study demonstrated the accurate, safe, and feasible use of a UAV as a tool for scene assessment by paramedic students at an MGE. No observed statistical difference was noted in a majority of both primary and secondary variables using a UAV for scene assessment versus SP.

The objective of this study was to estimate the impact of infestation pressures on the abundance of the parasitic sea louse, Lepeophtheirus salmonis, in the Bay of Fundy, New Brunswick (NB), Canada, using the Fish-iTrends database for the years 2009-2018. Infestation pressures were calculated as time-lagged weighted averages of the abundance of adult female (AF) sea lice within a site (internal infestation pressure: IIP) and among sites (external infestation pressure: EIP). The EIP weights were calculated from seaway distances among sites and a Gaussian kernel density for bandwidths of 5 to 60 km. The EIP with a bandwidth of 10 km had the best fit, as determined with Akaike's information criterion, and historical AF sea lice abundance. This estimated dispersal distance of 10 km was similar to previous studies in Norway, Scotland and in New Brunswick. The infestation pressures estimated from empirical AF sea lice abundance within and among sites significantly increased the abundance of AF sea lice (p

Introduction: The interpretation of electrocardiograms (ECGs) is an essential competency in modern paramedicine. Although educational guidelines for paramedic ECG interpretation exist, they are broad, not evidence-based, and lack prioritization in a prehospital clinical context. We conducted this study to gain consensus among stakeholders (EMS physicians, paramedic educators, and paramedic clinicians) regarding which ECG diagnoses or findings are most important for a practising advanced care paramedic to know. Methods: This study was an internet-based Delphi survey. We purposefully sampled participants in pairs (physician/paramedic) from all 10 Canadian provinces. Individuals rated a previously developed comprehensive list of emergency ECG diagnoses or findings on the importance of paramedic recognition and impact on prehospital care using a 4-point Likert scale. The consensus was achieved with a minimum of 75% agreement on Likert rating for a single diagnosis or finding during survey rounds one to three. When consensus was not reached, stability was defined as a shift of individual ratings between rounds of 20% or less. Results: All 20 participants completed the first and second rounds of the survey, and 17 (85%) completed three rounds. Overall, 32 (26.4%) of 121 potentially important ECG diagnoses or findings reached consensus, 2 (1.7%) reached stability and 87 (71.9%) reached neither consensus nor stability. Twenty-one (17.4%) diagnoses or findings were considered “Very Important”, six (4.9%) “Important”, and five (4.1%) “Minimally Important”. In the first round of the survey, the mean rating of the importance of a paramedic knowing a specific ECG diagnosis or finding was lower in the physician group than the paramedic group on 85 (72%) of 118 initial diagnoses or findings. Conclusion: We have created a list of ECG diagnoses or findings prioritized for the prehospital context that may assist paramedic educators in focusing on educational interventions. Many ECG diagnoses or findings failed to reach consensus or stability, demonstrating potential disagreement regarding clinical expectations for ECG knowledge among paramedics or physicians.

The parasitic salmon louse constrains growth in the Norwegian salmon farming industry through density dependent host-parasite interaction. Hence, there is a need for insight into how increases in salmon production, varying spatial organisation of the production and pest control strategies affect salmon louse population dynamics. Here we present a new salmon louse model for exploring effects of varying salmon farming conditions on spatio-temporal abundances of the parasite. The salmon louse model is partly stage-structured, comprising of (i) adult female lice and (ii) other mobile stages of lice. The abundance of adult females depend on survival of females from previous weeks and recruitment from the other mobile group of lice. The other mobiles also depend on survival of other mobiles from previous weeks, as well as recruitment from the previous generation of reproducing adult females from the same farm or from farms in the neighbourhood. In addition, expected abundances of the two stage-groups are modelled as functions of biological and physical covariates. The model is fitted to weekly salmon farm data covering all marine farms producing salmonids along the Norwegian cost over the years 2012–2016. Among novel results from fitting the model are estimates of the time-lag structure representing recruitment of other mobile lice from the previous generation adult females for different temperatures. Furthermore, the model estimates how various factors affect the susceptibility of fish on farms to louse infection and effects of treatments to control infection. Finally, the model estimates density dependent effects of increasing the number of fish in farms and of increasing the numbers of farms, on the rate of recruitment of other mobile lice. Analytically, the parameters representing density dependencies suggest that few farms with many fish and large between farm distances is effective in terms of minimising the overall output of salmon lice infection. Keywords: Salmon lice, Stage-structured model, Aquaculture

Skin ulcers have been increasing in occurrence on Atlantic salmon (Salmo salar) farms in Atlantic Canada during summer and autumn months when water temperatures are elevated above 10 °C. The clinical presentation in Atlantic Canada resembles lesions associated with winter ulcer disease in Europe caused by Moritella viscosa, but this bacterium is not always identified from skin lesions in North American cases. The objectives of our study were to: 1) describe the onset, duration, magnitude, and temporal and spatial distributions of Atlantic Canadian skin ulcer cases at the cage and farm levels; 2) develop hypotheses regarding potential sources and transmission routes for infection based on the patterns of disease occurrence; and 3) identify potential risk factors associated with total percent mortality during skin ulcer outbreaks. We summarized weekly cage-level data from 29 salmon farms in Atlantic Canada, from April 2014 to January 2016. Cage and farm-level prevalence, onset, duration, and total percent mortality associated with skin ulcer outbreaks were determined. The association of potential risk factors for skin ulcers with total percent mortality during skin ulcer outbreaks was assessed using a mixed-effects linear regression model with random farm effects. The overall farm-level prevalence of skin ulcers on Atlantic Canadian farms included in our study was 41%. The descriptive epidemiology of skin ulcers suggests cages are likely exposed to the causative agent(s) only at certain times of the year and exposure is not uniform across farms based on the patterns of disease occurrence. The onset of skin ulcer outbreaks in our study occurred from late-summer to mid-autumn. The pattern of disease is also suggestive of point source exposures to the causative agent across farms. In our final regression model, year of outbreak onset, and the interaction between the diagnosis of skin ulcers at the cage level and antibiotic treatment during the outbreaks were significantly associated with the log of total percent mortality during the outbreaks (P

A systematic review and meta-analysis was conducted to evaluate the appropriate tag:fish size ratio when tagging juvenile salmonids (genera Oncorhynchus, Salmo, and Salvelinus). The review yielded 18 publications with 211 control and treatment groups reporting results from laboratory studies on the effects of passive integrated transponder (PIT) tags, plus a small number of additional studies on acoustic transmitters. A meta-analysis of the PIT tagging studies showed significant heterogeneity among studies with respect to mortality. Meta-regression revealed that juvenile salmonid mortality increased curvilinearly with the tag:fish length ratio, indicating that mortality risk is rapidly enhanced as smaller fish or larger tag sizes are used. The tag:fish length ratio effect on daily length or mass gain increased linearly. The results provide an estimate of the effects of the tag:fish length ratio on mortality and growth parameters in juvenile salmonids. Based on this, we suggest that researchers can follow best practices for tagging juvenile salmonids with tags that are not greater than 17.5% of fish total length (TL). This equates a minimum size threshold of 131 mm TL for tagging salmonids with 23-mm PIT tags, and 69 mm TL with 12-mm PIT tags. This information can assist researchers, managers, and welfare agencies striving to use the best possible evidence to make informed decisions regarding fish tagging.

IntroductionThe proliferation of unmanned aerial vehicle (UAV) technology has the potential to change the way medical incident commanders (ICs) respond to mass-casualty incidents (MCIs) in triaging victims. The aim of this study was to compare UAV technology to standard practice (SP) in triaging casualties at an MCI.MethodsA randomized comparison study was conducted with 40 paramedic students from the Holland College Paramedicine Program (Charlottetown, Prince Edward Island, Canada). Using a simulated motor vehicle collision (MVC) with moulaged casualties, iterations of 20 students were used for both a day and a night trial. Students were randomized to a UAV or a SP group. After a brief narrative, participants either entered the study environment or used UAV technology where total time to triage completion, GREEN casualty evacuation, time on scene, triage order, and accuracy were recorded.ResultsA statistical difference in the time to completion of 3.63 minutes (95% CI, 2.45 min-4.85 min; P=.002) during the day iteration and a difference of 3.49 minutes (95% CI, 2.08 min-6.06 min; P=.002) for the night trial with UAV groups was noted. There was no difference found in time to GREEN casualty evacuation, time on scene, or triage order. One-hundred-percent accuracy was noted between both groups.Conclusion:This study demonstrated the feasibility of using a UAV at an MCI. A non-clinical significant difference was noted in total time to completion between both groups. There was no increase in time on scene by using the UAV while demonstrating the feasibility of remotely triaging GREEN casualties prior to first responder arrival.Jain T, Sibley A, Stryhn H, Hubloue I.Comparison of unmanned aerial vehicle technologyassisted triage versus standard practice in triaging casualties by paramedic students in a mass-casualty incident scenario. Prehosp Disaster Med. 2018;33(4):375–380

Clinical mastitis (CM) is one of the most frequent and costly diseases in dairy cows. A frustrating aspect of CM is its recurrent nature. This review was conducted to synthesize knowledge on risk of repeated cases of CM, effects of recurrent CM cases, and risk factors for CM recurrence. A systematic review methodology was used to identify articles for this narrative review. Searches were performed to identify relevant scientific literature published after 1989 in English or French from 2 databases (PubMed and CAB Abstracts) and 1 search platform (Web of Science). Fifty-seven manuscripts were selected for qualitative synthesis according to the inclusion criteria. Among the 57 manuscripts selected in this review, a description of CM recurrence, its risk factors, and effects were investigated and reported in 33, 37, and 19 selected manuscripts, respectively. Meta-analysis and meta-regression analyses were used to compute risk ratio comparing risk of CM in cows that already had 1 CM event in the current lactation with risk of CM in healthy cows. For these analyses, 9 manuscripts that reported the total number of lactations followed and the number of lactations with ≤1 and ≤2 CM cases were used. When summarizing results from studies requiring ≥5 d between CM events to consider a CM event as a new case, we observed no significant change in CM susceptibility following a first CM case (risk ratio: 0.99; 95% confidence interval: 0.86-1.14). However, for studies using a more liberal CM recurrence definition (i.e., only 24 h between CM events to consider new CM cases), we observed a 1.54 times greater CM risk (95% confidence interval: 1.20-1.97) for cows that already had 1 CM event in the current lactation compared with healthy cows. The most important risk factors for CM recurrence were parity (i.e., higher risk in older cows), a higher milk production, pathogen species involved in the preceding case, and whether a bacteriological cure was observed following the preceding case. The most important effects of recurrent CM were the milk yield reduction following a recurrent CM case, which was reported to be similar to that of the first CM case, and the increased risk of culling and mortality, which were reported to surpass those of first CM cases.

Limited research has been done using multivariable statistical methods to assess factors associated with fish mortality in warm-water finfish aquaculture in China. We carried out a case study to test the hypothesized association between pond-level daily mortality of farmed grass carp and predisposing environmental and husbandry factors. Based on logbook data from a single farm in Guangdong province (China) in 2013, two-stage time-series regression (TSR) analyses were conducted to estimate the lagged effect of these predisposing factors on grass carp mortality. Factors assessed included temperature fluctuations, movement of fish into and out of ponds, and 3 types of treatments (antibiotics-antiparasitics, traditional Chinese medicine-probiotics, and chemicals to improve water quality). First, coefficients were estimated using a generalized linear negative-binomial model for each pond, and these coefficient estimates were combined using meta-analytic techniques. Sensitivity analyses were done to compare effects of changes in the 3 modeling components: distributional forms, number of spline knots, and types of autocorrelation terms. Model results in the case study indicated 2 risk factors might be associated with increased mortality of grass carp: (1) movements-in of new fish during the previous 14 days; and (2) increasing water temperature during the previous 7 days. Sensitivity analyses indicated good consistency of the estimates with different modeling components. Our findings highlight the utility of assessing daily farm records using TSR to develop hypotheses about potential risk factors for grass carp mortality in China.

Accurate predictions for sea lice abundance can have a great impact on effective management of the parasite. Sea lice data are often from multiple production cycles coming from different aquaculture sites and exhibit strong process and observation variations, presenting challenges in developing effective prediction tools. Reliable predictions of sea lice abundance on aquaculture sites can save money and efforts in organizing effective control measures. A quantitative evaluation of different methods for estimating sea lice infestation pressure on aquaculture sites was presented in a preparatory paper ( Elghafghuf et al., 2020 ). In the current work, we used the favored method for infestation pressure and predicted future sea lice abundances on different parasitic life stages at the site level using a multivariate state-space model fitted to data from aquaculture sites located near Grand Manan Island in the Bay of Fundy, New Brunswick, Canada. We employed a rolling prediction procedure that did not require the prediction model to be refitted to the data at each time of prediction and compared our results with those from a similar approach involving re-estimation of the model at each prediction. The accuracies of predictions were assessed based on hold-out samples of data, whereby the predictions were computed without prior knowledge of these observations. The results showed that the non-updated-model procedure gave short-term (six weeks) predictions with reasonable accuracy, albeit lower prediction errors could be obtained with the updated-model approach. The performance of the non-updated-model prediction, as well as its practical and computational advantages, suggests it to be well suited for user-friendly implementation linked to underlying database. Additionally, the research quantified the contributions of predictive covariates such as infestation pressures to the sea lice predictions.

Multilevel data occur frequently in many research areas like health services research and epidemiology. A suitable way to analyze such data is through the use of multilevel regression models. These models incorporate cluster-specific random effects that allow one to partition the total variation in the outcome into between-cluster variation and between-individual variation. The magnitude of the effect of clustering provides a measure of the general contextual effect. When outcomes are binary or time-to-event in nature, the general contextual effect can be quantified by measures of heterogeneity like the median odds ratio or the median hazard ratio, respectively, which can be calculated from a multilevel regression model. Outcomes that are integer counts denoting the number of times that an event occurred are common in epidemiological and medical research. The median (incidence) rate ratio in multilevel Poisson regression for counts that corresponds to the median odds ratio or median hazard ratio for binary or time-to-event outcomes respectively is relatively unknown and is rarely used. The median rate ratio is the median relative change in the rate of the occurrence of the event when comparing identical subjects from 2 randomly selected different clusters that are ordered by rate. We also describe how the variance partition coefficient, which denotes the proportion of the variation in the outcome that is attributable to between-cluster differences, can be computed with count outcomes. We illustrate the application and interpretation of these measures in a case study analyzing the rate of hospital readmission in patients discharged from hospital with a diagnosis of heart failure.

Bacterial kidney disease (BKD) diagnosis is often carried out by IFAT, ELISA, and PCR because these tests yield rapid results compared with bacterial culture for the causative agent, Renibacterium salmoninarum. However, the diagnostic sensitivity (DSe) and specificity (DSp) of these tests is generally unknown, particularly in subclinically infected Atlantic salmon. Bayesian models were used to analyse test results from 454 field samples sourced from salmon populations with different infection status and submitted to independent laboratories. Results showed that DSe was highly dependent on the presentation of infection. When applied to fish with BKD-associated gross lesions, the highest to lowest posterior medians for DSe were: PCR2 (0.98), PCR1 (0.97), bacterial culture (0.86), ELISA (0.82) and IFAT (0.75). When applied to fish without lesions, the posterior medians for DSe were: PCR1 (0.82), PCR2 (0.82), bacterial culture (0.29), IFAT (0.29) and ELISA (0.21). The posterior medians for DSp were similar in populations with and without lesions. ELISA had the highest DSp (0.99), followed by culture (0.98–0.99), IFAT (0.96), PCR1 (0.94–0.96) and PCR2 (0.83–0.84), where different numbers reflect the estimates for populations with or without lesions respectively. Among tests that were evaluated for intra-laboratory repeatability (ELISA, PCR1 and IFAT), ELISA had the highest repeatability (kappa = 0.82). We concluded that PCR tests were the fittest of the evaluated tests for the purpose of screening subclinically-infected adult Atlantic salmon.

The Mekong Delta in Vietnam is one of the most productive aquaculture regions in the world, in which the red tilapia (Oreochromis spp.) industry is a small-scale industry that mainly supplies local markets in the delta region. Little is known about the frequency of mortality events and health management in this sector. We describe red tilapia floating cage production systems in the Mekong Delta, Vietnam, for the purposes of quantifying mortality and associated production factors, and describing practices that may influence pathogen introduction and spread to and from farms. In July 2014, approximately 50 red tilapia farmers from 4 provinces (201 farmers in total) were randomly selected and interviewed. Median overall perceived mortality (PM) within a production cycle was 35%. Overall PM was found to be affected by province (p < 0.01), age of farmers (p = 0.01), anticipated main reason for PM in the first 2 wk (p = 0.03), most common market for the fish (p = 0.02), and whether farmers recorded stocking information (p = 0.01). Based on the interviews, we describe and discuss processes that potentially affect pathogen introduction and spread on these farms, such as movements of live and dead fish, distances between farms, mechanical transmission, and biosecurity practices such as treating fish before stocking, using disinfectants, and sharing equipment, and harvesters' movements. This study provides fundamental understanding of red tilapia aquaculture management in the Mekong Delta, and describes management factors that could become important in the event of disease outbreaks.

The sea louse is considered an important ectoparasite that affects farmed salmonids around the world. Sea lice control relies heavily on pharmacological treatments in several salmon-producing countries, including Chile. Among options for drug administration, immersion treatments represent the majority of antiparasitic control strategies used in Chile. As a topical procedure, immersion treatments do not induce a long lasting effect; therefore, re-infestation from neighbouring farms may undermine their efficacy. Synchronization of treatments has been proposed as a strategy to improve immersion treatment performance, but it has not been evaluated so far. Using a repeated-measures linear mixed-effect model, we evaluated the impact of treatment synchronization of neighbouring farms (within 10km seaway distance) on the adult lice mean abundance from weeks 2 to 8 post-treatment on rainbow trout and Atlantic salmon farms in Chile, while controlling for external and internal sources of lice before the treatments, and also for environmental and fish-related variables. Results indicate that treatment synchronization was significantly associated with lower adult lice levels from weeks 5 to 7 after treatment. This relationship appeared to be linear, suggesting that higher levels of synchronization may result in lower adult sea lice levels during these weeks. These findings suggest that synchronization can improve the performance of immersion delousing treatments by keeping sea lice levels low for a longer period of time. Our results may be applicable to other regions of the world where immersion treatments are widely used.

Soft-shelled lobsters pose economic challenges to the lobster industry due to low meat yields and survivability during holding and transportation. Our objectives were to describe spatio-temporal patterns of soft-shelled lobsters in southwestern Nova Scotia, and identify environmental and lobster-related factors associated with shell quality. We analyzed data obtained from a broad-scale, intensive monitoring project and remotely sensed water temperatures. Mixed-effect logistic regression and linear regression methods analyzed more than 130 000 samples collected between 2004 and 2014. The annual overall prevalence of soft-shelled lobsters ranged from 9% to 38% and varied significantly among fishing areas. Shell quality was influenced by sex and size, and in the 2 months before the fishing season, lower water temperatures (4–6 weeks prior to sampling) were associated with reduced prevalence of soft-shells. High annual variability of soft-shell prevalence, that water temperature alone could not explain, suggests that adjusting fishing seasons, arbitrarily, in two fishing areas will not improve the overall shell quality of landed lobsters. Further research is needed to evaluate the effects of long-term temperature and ecosystem changes on lobster health in eastern Canada.

Marine finfish aquaculture is a rapidly growing subsector in the Asia-Pacific region, including Vietnam. However, in-depth information about health management practices is often inadequate. Our objective was to describe multi-species marine finfish aquaculture in northern Vietnam at the farm and species level, and identify practices that may influence fish health. Two surveys were conducted in April 2014 and April 2015 on respectively 120 and 119 farms of which 57% were the same farms, located in floating villages near Cat Ba Island in Hai Phong Province, Vietnam. Most management practices were not different between the multiple species per farm. Duration of grow-out season was part of both surveys and differed for most species between surveys, and also with findings from other studies. Most farmers did not have aquaculture related education. Few farmers recorded stocking, harvesting or mortality parameters, and there was little involvement of health professionals. Most stock originated from China, which could pose a risk on emerging diseases. Median proximity of farms was 3 m, which is a large potential for spread of pathogens between farms. There were few biosecurity practices in place to prevent pathogens from entering the farm, e.g. few farmers treated fish before stocking, and none indicated disinfection of harvesters. Overall mortality was different between species, but overall 50–75% was expected for many production cycles. This study provides a basic understanding that could inform future outbreak investigations or development of risk-based surveillance programs. Statement of relevance This is the first study that provides a basic understanding of health related factors in marine finfish aquaculture management in northern Vietnam. As the sector is growing, early interventions to adapt farmers to better practices may lead to a cascade of improvements, and may optimize and stabilize the sector as more families become dependent upon the industry for their livelihoods.

Frailty models can be fit as mixed-effects Poisson models after transforming time-to-event data to the Poisson model framework. We assess, through simulations, the robustness of Poisson likelihood estimation for Cox proportional hazards models with log-normal frailties under misspecified frailty distribution. The log-gamma and Laplace distributions were used as true distributions for frailties on a natural log scale. Factors such as the magnitude of heterogeneity, censoring rate, number and sizes of groups were explored. In the simulations, the Poisson modeling approach that assumes log-normally distributed frailties provided accurate estimates of within- and between-group fixed effects even under a misspecified frailty distribution. Non-robust estimation of variance components was observed in the situations of substantial heterogeneity, large event rates, or high data dimensions.

Background A small proportion of the population consumes the majority of health care resources. High-cost health care users are a heterogeneous group. We aim to segment a provincial population into relevant homogenous sub-groups to provide actionable information on risk factors associated with high-cost health care use within sub-populations. Methods The Canadian Institute for Health Information (CIHI) Population Grouping methodology was used to define mutually exclusive and clinically relevant health profile sub-groups. High-cost users (> = 90th percentile of health care spending) were defined within each sub-group. Univariate analyses explored demographic, socio-economic status, health status and health care utilization variables associated with high-cost use. Multivariable logistic regression models were constructed for the costliest health profile groups. Results From 2015 to 2017, 1,175,147 individuals were identified for study. High-cost users consumed 41% of total health care resources. Average annual health care spending for individuals not high-cost were $642; high-cost users were $16,316. The costliest health profile groups were ‘long-term care’, ‘palliative’, ‘major acute’, ‘major chronic’, ‘major cancer’, ‘major newborn’, ‘major mental health’ and ‘moderate chronic’. Both ‘major acute’ and ‘major cancer’ health profile groups were largely explained by measures of health care utilization and multi-morbidity. In the remaining costliest health profile groups modelled, ‘major chronic’, ‘moderate chronic’, ‘major newborn’ and ‘other mental health’, a measure of socio-economic status, low neighbourhood income, was statistically significantly associated with high-cost use. Interpretation Model results point to specific, actionable information within clinically meaningful subgroups to reduce high-cost health care use. Health equity, specifically low socio-economic status, was statistically significantly associated with high-cost use in the majority of health profile sub-groups. Population segmentation methods, and more specifically, the CIHI Population Grouping Methodology, provide specificity to high-cost health care use; informing interventions aimed at reducing health care costs and improving population health.

To reduce the use of insecticide treatments against Haematobia irritans we evaluated the impact of treating 15% of the bovines, with the greatest number of flies including bulls, with 40% diazinon ear tags, on the infestation of untreated cows. Horn fly susceptibility to diazinon was measured before and after treatment, and peaks of infestation were recorded. Three groups of Bradford bovines were evaluated: Group 1 (control untreated), Group 2 (15% treated) and Group 3 (control 100% treated). Weekly counts of horn flies were performed on the same animals for 78 days. Two peaks of infestation were recorded, and a higher number of horn flies occurred in the untreated control group than in the untreated cows of the selectively treated group throughout the entire period of the study, except for a single week. The horn fly field population was significantly more susceptible to diazinon than the reference susceptible strain both before and after insecticide treatment. In conclusion, treatment of 15% of the most infested animals from a herd, with 40% diazinon ear tags, quickly reduced horn fly infestations of the entire herd and may be a practical approach for horn fly control, reducing costs and chemical use.

Over the past 30 yr, the prevalence of bovine leukemia virus (BLV) infection has increased in North America, including Atlantic Canada, at both the herd and individual cow levels. This has occurred despite increased awareness of the disease and its deleterious effects and despite implementation of management practices aimed at reducing disease transmission. Our objectives were to identify risk factors associated with the within-herd prevalence of BLV-infected cows by using a risk assessment and management program workbook, as well as to determine the current level of BLV prevalence in the Atlantic Canada region. We hypothesized that previously established risk factors, including management practices associated with calf rearing and fly control, would affect within-herd BLV prevalence. Bulk tank milk (BTM) samples were collected in January and April of 2016 and again during the same months in 2017 and 2018 from all dairy farms shipping milk in the region. Samples were tested with ELISA for levels of anti-BLV antibodies to estimate within-herd prevalence. Regional BLV prevalence at the herd level was 88.39% of dairy herds infected in 2016 and 89.30% in 2018. All dairy farms shipping milk and who had BTM samples collected in 2017 (n = 605) were eligible to participate in the risk assessment and management program questionnaire (RAMP), which was developed and distributed to all bovine veterinarians in Atlantic Canada. One hundred and six RAMP were returned, with representation from all 4 provinces. The RAMP results were combined with the mean BTM ELISA results, and univariable logistic regression followed by multivariable logistic regression was performed to investigate the association between RAMP risk factors and the estimated within-herd BLV prevalence. Factors in the multivariable model significantly associated with the odds of a herd being classified as >25% estimated within-herd prevalence included history of diagnosis of clinical BLV and calves receiving colostrum from cows with unknown BLV status. Differences in within-herd prevalence were not associated with hypodermic needle and injection practices, rectal sleeve practices, or using bulls for natural breeding, based on these 106 dairy farms.

Sea lice are ectoparasites of salmonids, and are considered to be one of the main threats to Atlantic salmon farming. Sea lice infestation on a farm is usually initiated by attachment of the free-living copepodid stage derived from the surrounding water, frequently originating from adult lice on the same farm or from neighboring salmonid farms, referred to as internal and external sources, respectively. Various approaches have been proposed to quantify sea lice infestation pressure on farms to improve the management of this pest. Here, we review and compare five of these methods based on sea lice data from 20 farms located near Grand Manan island in the Bay of Fundy, New Brunswick, Canada. Internal and external infestation pressures (IIP and EIP, respectively) were estimated using different approaches, and their effects were modeled either by a unique parameter for all production cycles or by different parameters for each production cycle, using a multivariate state-space model. Predictive variables, such as water temperature and sea lice treatments, were included in the model, and their effects across production cycles were estimated along with those of other model parameters. Results showed that models with only EIP explained the variation in the data better than models with only IIP, and that models with unique IIP and unique EIP for all cycles were generally associated with the best model fit. The simplest, fixed lag method for calculating infestation pressure had the best predictive performance in our models among the methods studied.

Bacterial Kidney Disease (BKD) is an economically significant disease in salmonid aquaculture and commonly requires antibiotic treatments to reduce its impact. Once a pen of fish is diagnosed with BKD, fish are considered chronically infected, potentially until harvest. Although there appears to be little or no evidence to support it, it is often assumed that subclinical infections affect productivity over the long term. We used a 2-stage hierarchical interrupted time series (ITS) analysis in an attempt to quantify the effect of subclinical BKD on mortality, growth, and food conversion ratio (FCR) of Atlantic salmon cultured in marine farms in Atlantic Canada. For all three outcomes, BKD had for some site cycles a positive effect, and for others a negative effect. Overall, the effect of BKD on mortality and growth could not be detected (effect -0.08 ((95% ci: -0.51, 0.35) and 0.00 (-0.02, 0.02)), while a very small effect showing an increase in FCR was detected (0.07 (-0.01, 0.15)). We hypothesized that minimal interference with fish performance may be compatible with the ecology of Renibacterium salmoninarum, the causative agent of BKD. For this organism, vertical transmission is a primary mode of propagation in low-density host populations as found in the wild. Since farms are always adapting and optimizing their farm management of BKD, these constant adjustments may also have negated our ability to detect the effect of many factors contributing to BKD productivity impacts. Hierarchical ITS analysis is considered an appropriate methodology to investigate the complex relationships with productivity measures over time under farming conditions. In the highly innovative salmon aquaculture industry, health records generating data available for time-series analysis is expected to become more accurate and abundant in the future, providing more opportunities for time-series regression studies.