Scenario tree modelling to inform surveillance design for maintaining freedom from Coxiella burnetii infection in Australian commercial dairy goat herds.

We used scenario tree methods to determine how different disease detection methods might be used to provide quantitative evidence that Australian dairy goat herds are free of coxiellosis. The aim of our proposed C. burnetii surveillance programme is to find evidence of the absence of antigen as well as evidence of an absence of an immune response to C. burnetii infection in individual dairy goat herds. We defined a C. burnetii infected dairy goat herd as a herd in which at least one doe was showing evidence of either active infection or past C. burnetii exposure using four candidate surveillance system components (SSCs): (1) testing of individual doe whole blood using the C. burnetii com1 PCR; (2) testing of individual doe whole blood using the C. burnetii ELISA; (3) testing bulk tank milk (BTM) using the com1 PCR and the C. burnetii ELISA; and (4) investigations of abortions and stillborn kids submitted to a diagnostic laboratory for testing. Of eight candidate surveillance strategies (combinations of the SSCs listed above) individual doe ELISAs every six months combined with monthly BTM PCR and ELISA testing returned the highest surveillance system sensitivity of 0.963 (95% probability interval [PI] 0.911-0.982) for the lowest cost, at AUD 28.94 (95% PI 28.38-30.59) over a 12-month period, for every one percent increase in surveillance system sensitivity. Assuming a probability of disease freedom of 0.10 at the start of the surveillance program and a probability of C. burnetii introduction per month of 0.01 we estimate that 95% confidence that C. burnetii was absent from a herd could be achieved after a single round of individual doe ELISAs followed by period of 6 consecutive monthly BTM PCR and ELISA tests. The results of this study show that selection of the most efficient combination of surveillance system components requires a good understanding of initial herd C. burnetii status and the probability of introduction of infection and how this may change over time. Scenario tree analyses results have provided insight into the key determinants of C. burnetii detection ability.

Shrimp MultiPath™ multiplexed PCR white spot syndrome virus detection in penaeid shrimp.

White spot syndrome virus (WSSV), which causes white spot disease, is one of the notoriously feared infectious agents in the shrimp industry, inflicting estimated production losses world-wide of up to US$1 billion annually. Cost-effective accessible surveillance testing and targeted diagnosis are key to alerting shrimp industries and authorities worldwide early about WSSV carrier status in targeted shrimp populations. Here we present key validation pathway metrics for the Shrimp MultiPathTM (SMP) WSSV assay as part of the multi-pathogen detection platform. With superior throughput, fast turn-around time, and extremely low cost per test, the SMP WSSV assay achieves a high level of analytical sensitivity (~2.9 copies), perfect analytical specificity (~100%), and good intra- and inter-run repeatability (coefficient of variation <5%). The diagnostic metrics were estimated using Bayesian latent class analysis on data from 3 experimental shrimp populations from Latin America with distinct WSSV prevalence and yielded a diagnostic sensitivity of 95% and diagnostic specificity of 99% for SMP WSSV, which was higher than these parameters for the TaqMan quantitative PCR (qPCR) assays currently recommended by the World Organisation for Animal Health and the Commonwealth Scientific and Industrial Research Organisation. This paper additionally presents compelling data for the use of synthetic double-stranded DNA analyte spiked into pathogen-naïve shrimp tissue homogenate as a means to substitute clinical samples for assay validation pathways targeting rare pathogens. SMP WSSV shows analytical and diagnostic metrics comparable to qPCR-based assays and demonstrates fit-for-purpose performance for detection of WSSV in clinically diseased and apparently healthy animals.

Seroprevalence of Coxiella burnetii antibodies in wild deer populations in eastern Australia.

Coxiella burnetii causes significant reproduction losses in livestock and the disease Q fever in humans. Transmission of C. burnetii is facilitated by the stability of the bacterium in the environment and the susceptibility of a variety of host species to infection. Consequently, inter-species transmission occurs frequently through either direct or indirect contact. Wildlife may represent reservoirs of C. burnetii and could therefore be a source of infection for domestic animals. Understanding the prevalence of C. burnetii infections at the wildlife-livestock interface is important for disease control. This study aimed to investigate the extent of C. burnetii exposure in wild deer in eastern Australia. Serum samples were obtained from 413 wild deer from seven regions in four eastern Australian states from 2017 to 2020. Antibodies were detected using a commercial Q fever antibody kit validated for ruminants. Seroprevalence of C. burnetii antibodies in deer was determined and true prevalence estimated, for each region. The overall seroprevalence of C. burnetii antibodies in wild deer was 3.4% (14 seropositive of 413 deer sampled) with true prevalence estimated to be 4.3% (95% credible interval: 0.6%, 10.9%). Seropositive deer were identified only in Queensland (7/108 seropositive) and northern New South Wales (7/120 seropositive). This geospatial distribution is consistent with seropositivity in other animal species and indicative of the level of C. burnetii in the environment. The low seroprevalence suggests that wild deer are unlikely to be a major reservoir species for C. burnetii in eastern Australia but may still be implicated in inter-species transmission cycles.

A cross-sectional survey of risk factors for the presence of Coxiella burnetii in Australian commercial dairy goat farms.

The largest Australian farm-based outbreak of Q fever originated from a dairy goat herd. We surveyed commercial dairy goat farms across Australia by testing bulk tank milk (BTM) samples using a commercial indirect enzyme-linked immunosorbent assay and two quantitative polymerase chain reactions (PCRs). Of the 66 commercial dairy goat herds on record, managers from 61 herds were contacted and 49 provided BTM samples. Five of the surveyed herds were positive on at least one of the diagnostic tests, thus herd-level apparent prevalence was 10% (95% confidence interval [CI] 4 to 22). True prevalence was estimated to be 3% (95% credible interval: 0 to 18). Herd managers completed a questionnaire on herd management, biosecurity and hygiene practices and risk factors were investigated using multivariable logistic regression. Herds with >900 milking does (the upper quartile) were more likely to be Coxiella burnetii positive (odds ratio = 6.75; 95% CI 1.65 to 27.7) compared with farms with ≤900 milking does. The odds of BTM positivity increased by a factor of 2.53 (95% CI 1.51 to 4.22) for each order of magnitude increase in the number of goats per acre. C. burnetii was not detected in samples from the majority of the Australian dairy goat herds suggesting there is an opportunity to protect the industry and contain this disease with strengthened biosecurity practices. Intensification appeared associated with an increased risk of positivity. Further investigation is required to discriminate the practices associated with an increased risk of introduction to disease-free herds, from practices associated with maintenance of C. burnetii infection in infected dairy goat herds.

Enterocytozoon hepatopenaei real-time and Shrimp MultiPathTM PCR assay validation for South-East Asian and Latin American strains of Penaeid shrimp.

Enterocytozoon hepatopenaei (EHP) infections are a global challenge for the Penaeid shrimp industry with a sharp rise in prevalence over the last 10 yr. EHP is known to cause sub-optimal growth, large size variation and reduced survival of shrimp. Molecular methods development has mainly focussed on 18S rRNA or spore wall protein 1 (SWP1). Due to the specificity and sensitivity issues with previously designed assays for both targets, new molecular assays are needed by the global shrimp industry and regulators to help manage the risks posed by EHP. This paper describes new real-time PCR (qPCR) methods developed for the novel EHP gene targets polar tube protein 2 (PTP2) and spore wall protein 26 (SWP26), whilst also presenting performance metrics of the new Shrimp MultiPathTM technology EHP assay. qPCR assays PTP2G and SWP26G show high amplification efficiency, a limit of detection (LOD) of between 1 and 4 copies, low assay variation and high diagnostic sensitivity (DSe) and specificity (DSp) compared to imperfect reference assays. Similar performance is seen with Shrimp MultiPathTM EHP showing an LOD of 8 copies, low assay variation and high DSe and DSp. These novel molecular targets for EHP and Shrimp MultiPathTM EHP strengthen global efforts to monitor and mitigate risks of EHP infections and outbreaks. Moreover, this study presents novel data on distribution of EHP in shrimp populations from South-East Asia and Latin America, and how sequence variations need to be considered when monitoring EHP in different geographies.

Participation of Victorian Thoroughbreds in the racing industry: a whole-of-population benchmark.

The proportion of Thoroughbred (TB) horses that commence training and eventually race, is an important industry-level indicator of how successful it is at producing horses suitable for racing. It is also of interest to the wider community and is central to the issue of whether there is overbreeding in the Australian TB industry. This study investigated the training and racing records for the 2005 and 2010 Victorian TB foal crops to determine the proportion of TBs that train and race, and the age of entering training and first race start. Subsets of the foal crop were also examined to determine if premier yearling sale cohorts would produce selection bias. The Australian Stud Book (ASB) registered 7662 TB horses born in Victoria in 2005 (n = 4116) and 2010 (n = 3546). Of these, 5614 (73%) entered training and 4868 (64%) started in at least one race. Fourteen percent (n = 1045) of the study cohort had their first race start as 2-year-olds and 35% (n = 2644) had their first start as 3-year-olds. A higher proportion of TB horses that attended premier yearling sales entered training (93%) and raced (84%). This study established a baseline for training and racing milestones, such as the proportion and age that horses commenced training, and age of first start using population-level data. It also established that the use of subsets of the population can introduce selection bias.

Factors associated with racing performance and career duration for Victorian-born Thoroughbreds.

The number of horses leaving the Australian Thoroughbred (TB) racing industry each year is of concern to animal welfare advocates, public and regulators. A horse's previous athletic performance is a significant driver of retirement from racing. Racehorse performance can be measured in terms of the total number of starts, duration of racing and prize money earned. This study investigated Australian racing records for the 2005 and 2010 Victorian TB foal crops to identify factors associated with total number of starts, racing career duration, prize money earned and age of last race start-up to the 10-year-old racing season. Racing Australia registered 4,577 TB horses born in Victoria in 2005 (n = 2,506) and 2010 (n = 2,071) that raced in Australia. Horses that started racing at 2-years of age had fewer race starts in their first racing season but an increased total number of starts, prize money and duration of racing. The median age of last start (LS) was five (Q1 4; Q3 7) years. Horses that had won a race, had a maximum handicap rating of 61 or above and those racing over distances of more than 2,400 m had an increased racing career duration and an age of last race start greater than 6-years of age. Horses participating in jumps races (n = 63) had the longest careers and older age of LS. These horses were more likely to have had a handicap rating over 80 and were just as likely to start their racing careers as 2-years-olds.

Bayesian latent class analysis when the reference test is imperfect.

Latent class analysis (LCA) has allowed epidemiologists to overcome the practical constraints faced by traditional diagnostic test evaluation methods, which require both a gold standard diagnostic test and ample numbers of appropriate reference samples. Over the past four decades, LCA methods have expanded to allow epidemiologists to evaluate diagnostic tests and estimate true prevalence using imperfect tests over a variety of complex data structures and scenarios, including during the emergence of novel infectious diseases. The objective of this review is to provide an overview of recent developments in LCA methods, as well as a practical guide to applying Bayesian LCA (BLCA) to the evaluation of diagnostic tests. Before conducting a BLCA, the suitability of BLCA for the pathogen of interest, the availability of appropriate samples, the number of diagnostic tests, and the structure of the data should be carefully considered. While formulating the model, the model's structure and specification of informative priors will affect the likelihood that useful inferences can be drawn. With the growing need for advanced analytical methods to evaluate diagnostic tests for newly emerging diseases, LCA is a promising field of research for both the veterinary and medical disciplines.

L'analyse à classes latentes a permis aux épidémiologistes de surmonter les problèmes concrets posés par les méthodes traditionnelles d'évaluation des essais de diagnostic, qui nécessitent à la fois un test de référence absolue (étalon ou gold standard) et un grand nombre d'échantillons de référence aux caractéristiques appropriées. Au cours des quatre dernières décennies, les méthodes d'analyse à classes latentes ont acquis de l'ampleur et permettent aux épidémiologistes d'évaluer les essais diagnostiques et d'estimer les taux de prévalence réelle tout en recourant à des tests supposés imparfaits, grâce à l'utilisation de données et de scénarios divers et complexes, y compris dans les situations d'émergence de nouvelles maladies infectieuses. Les auteurs font un tour d'horizon des dernières évolutions dans ce domaine et donnent des orientations pratiques concernant la manière d'utiliser l'analyse bayésienne à classes latentes pour évaluer les performances d'un test de diagnostic. Avant de conduire une telle analyse, il convient de déterminer avec soin si elle est adaptée à l'agent pathogène considéré et si les échantillons disponibles sont appropriés et en nombre suffisant ; il convient également de prendre en compte le nombre de tests de diagnostic à évaluer et la structure des données utilisées. Lors de la conception du modèle, sa structure et la définition préalable des données informatives vont affecter la probabilité que le modèle génère des inférences utiles. Face à la nécessité croissante de disposer de méthodes analytiques sophistiquées pour évaluer les tests de diagnostic utilisés pour les maladies émergentes nouvelles, les analyses à classes latentes offrent des perspectives prometteuses pour la recherche, aussi bien dans le domaine de la santé vétérinaire que de la médecine humaine.

El análisis de clases latentes ha servido a los epidemiólogos para superar las limitaciones prácticas que imponen los métodos tradicionales de evaluación de pruebas de diagnóstico, que requieren a la vez una prueba de diagnóstico que sirva de patrón de referencia perfecto y un gran número de muestras de referencia adecuadas. En los últimos cuatro decenios, los métodos de análisis de clases latentes se han ido ampliando hasta permitir a los epidemiólogos evaluar pruebas de diagnóstico y calcular la prevalencia real empleando pruebas imperfectas ante muy diversas estructuras de datos y situaciones complejas, incluida la aparición de nuevas enfermedades infecciosas. Los autores, tras presentar a grandes líneas los últimos adelantos en cuanto a métodos de análisis de clases latentes, ofrecen indicaciones prácticas para aplicar el análisis bayesiano de clases latentes a la evaluación de pruebas de diagnóstico. Antes de proceder a un análisis bayesiano de este tipo conviene estudiar con detenimiento la idoneidad del método para el patógeno en cuestión, la disponibilidad de muestras apropiadas, el número de pruebas de diagnóstico y la estructura de los datos. A la hora de formular el modelo, la estructura del propio modelo y la especificación de los elementos informativos previos influirán en la probabilidad de poder extraer conclusiones provechosas. Ante la creciente necesidad de disponer de métodos analíticos avanzados con los que evaluar pruebas de diagnóstico de nuevas enfermedades emergentes, el análisis de clases latentes abre un promisorio campo de investigación para las disciplinas veterinarias y médicas.

Introduction - Validation of tests for OIE-listed diseases as fit-for-purpose in a world of evolving diagnostic technologies.

The World Organisation for Animal Health (OIE) has made leading contributions to the discipline of test validation science by providing standards and guidelines that inform the test validation process in terrestrial and aquatic animals. The OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals, and the Manual of Diagnostic Tests for Aquatic Animals describe the test validation pathway in the context of fitness for purpose, elaborate on the importance of diagnostic sensitivity (DSe) and specificity (DSp) as measures of test accuracy, and designate additional factors (e.g. test cost, laboratory throughput capacity and rapidity of test results) that influence choices of a single test over others or the inclusion of a new test in a diagnostic process that includes multiple tests. This paper provides examples of each of the six main testing purposes listed in the Terrestrial Manual and describes additional metrics such as ruggedness and robustness that should be included in the validation of point-of-care tests. Challenges associated with new diagnostic technologies and platforms are described. Validated tests with estimates of DSe and DSp are needed to measure confidence in test results for OIE-listed diseases, to facilitate risk assessments related to animal movement, to estimate true prevalence, and for certification of disease freedom and use in epidemiological (risk factor) studies.

L'Organisation mondiale de la santé animale (OIE) a apporté d'importantes contributions dans le domaine de la validation des tests en élaborant des normes et des lignes directrices qui informent sur le processus de validation des tests chez les animaux terrestres et aquatiques. Le Manuel des tests de diagnostic et des vaccins pour les animaux terrestres et le Manuel des tests de diagnostic pour les animaux aquatiques de l'OIE décrivent le processus de validation des tests dans le contexte de leur aptitude à l'emploi, expliquent l'importance de la sensibilité (DSe) et de la spécificité (DSp) diagnostiques pour mesurer l'exactitude des tests, et désignent d'autres facteurs (ex. coût des tests, capacité de traitement des laboratoires et rapidité d'obtention des résultats des tests) qui influencent le choix d'un test par rapport à un autre ou l'inclusion d'un nouveau test dans un processus de diagnostic composé de multiples tests. Le présent article fournit des exemples pour chacun des six principaux objectifs définis pour les tests figurant dans le Manuel terrestre et décrit des mesures supplémentaires, telle la robustesse (aussi bien interne qu'externe), qu'il conviendrait d'inclure dans la validation des tests au point d'intervention. Il aborde également les défis soulevés par les nouvelles technologies et plateformes de diagnostic. Des tests validés accompagnés d'estimations de la DSe et de la DSp sont nécessaires pour mesurer la fiabilité des résultats des tests pour les maladies listées par l'OIE, faciliter les évaluations des risques associés aux mouvements des animaux, estimer le véritable taux de prévalence et certifier l'absence de maladies ; ils sont également indispensables pour les études (des facteurs de risque) épidémiologiques.

La Organización Mundial de Sanidad Animal (OIE), con su labor de elaboración de normas y directrices que fundamentan el proceso de validación de pruebas para enfermedades de los animales terrestres y acuáticos, ha hecho aportaciones punteras a la disciplina científica que se ocupa de la validación de pruebas. En su Manual de las Pruebas de Diagnóstico y de las Vacunas para los Animales Terrestres y su Manual de las Pruebas de Diagnóstico para los Animales Acuáticos, la OIE describe el procedimiento de validación de pruebas en clave de idoneidad para determinados propósitos, ahonda en la importancia de la sensibilidad y la especificidad diagnósticas (DSe y DSp) como medidas de la exactitud de una prueba y señala otros factores (como el costo de la prueba, la productividad del laboratorio o la rapidez de los resultados) que también influyen en la elección de una determinada prueba por delante de otras o en la inclusión de una nueva prueba en un proceso de diagnóstico que entraña el uso de varias. Los autores ofrecen ejemplos de cada uno de los seis principales propósitos con las que puede utilizarse una prueba, según vienen enunciados en el Manual Terrestre, y describen otros parámetros que es preciso tener en cuenta a la hora de validar pruebas practicadas en el punto de consulta, como la robustez o también la solidez (ruggedness en inglés; llamada a veces «robustez interlaboratorios¼). También describen las dificultades ligadas a nuevas tecnologías y plataformas de diagnóstico. Se necesitan pruebas validadas y acompañadas de un cálculo de la DSe y la DSp para fines tan diversos e importantes como medir la confianza que merecen los resultados de pruebas para enfermedades inscritas en las listas de la OIE, facilitar la evaluación del riesgo ligado al desplazamiento de animales, estimar la prevalencia real, certificar la ausencia de enfermedad o realizar estudios epidemiológicos (factores de riesgo).

Prevalence and spatial distribution of Coxiella burnetii seropositivity in northern Australian beef cattle adjusted for diagnostic test uncertainty.

Q fever is a zoonotic disease caused by infection with Coxiella burnetii transmitted from animals including, but not limited to, cattle, sheep and goats. The infection in cattle is typically sub-clinical with some evidence suggesting associated reproductive loss. There is currently limited data on the true prevalence and distribution of coxiellosis in beef cattle across northern Australia. During this study, 2,012 sera samples from beef cattle managed on commercial farms located in Queensland and the Northern Territory were tested using an indirect immunofluorescent assay (IFA) for serological evidence of IgG antibodies against C. burnetii. Bayesian latent class models were used to estimate the true prevalence, adjusted for diagnostic test sensitivity and specificity and incorporating the hierarchical structure of the cattle within farms and regions. In this study, cattle in the Northern Territory had lower estimated true prevalence than cattle within most regions of Queensland with the exception of south-east Queensland. Results from this study have described the geographic distribution and estimated the true prevalence of antibodies to C. burnetii in a sample of extensively managed beef cattle located across the tropical grazing regions of northern Australia.

Serological responses of Australian horses using a commercial duplex indirect ELISA following vaccination against strangles.

OBJECTIVE: To determine the nature of serological responses in Australian horses using a commercial duplex indirect ELISA (iELISA) following vaccination against strangles. DESIGN: A group (n = 19) of client-owned horses from five properties were recruited to receive a primary course of a Streptococcus equi subsp. equi (S. equi) extract vaccine. Serological responses were determined by duplex iELISA incorporating S. equi-specific fragments of two cell wall proteins, SEQ2190 and SeM (antigens (Ag) A and C, respectively). METHODS: The horses were administered a primary strangles vaccination course. Blood was collected immediately prior to each of the three vaccinations at 2-week intervals and additionally at 28 and 56 days following the 3rd vaccination (V3). RESULTS: Significant increases in mean antibody levels of horses following vaccination were limited only to AgC, which was significantly increased at T2/V3, 14 days following V2 (ratio of geometric means = 3.7; 95% confidence interval (CI): 1.6, 8.4; P = 0.003). There was no increase in mean antibody to Ag A (ratio of geometric means = 1.4; 95% CI: 0.6, 3.2; P = 0.39). Four horses (22%) exceeded the test cut-off for AgC following vaccination. CONCLUSION: Vaccination of Australian horses is unlikely to interfere greatly with detection of strangles using the duplex iELISA. No responses would be anticipated to AgA following vaccination with Equivac© S/Equivac© 2in1 and only a minority are likely to respond to AgC. We conclude that the results of this study validate the usefulness of the duplex iELISA to assist control measures for strangles outbreaks in Australian horse populations.

Review of 20 years of human acute Q fever notifications in Victoria, 1994-2013.

OBJECTIVE: To describe the epidemiological and clinical features of acute Q fever in Victoria from 1994 to 2013. DESIGN: Retrospective case series and spatiotemporal analyses of human notification data. METHODS: Records for all confirmed cases of Q fever in Victoria notified between 1994 and 2013 were reviewed. Clinical and epidemiological features of the cases were described and spatiotemporal analysis undertaken for all cases potentially acquired within Victoria. RESULTS: A total of 659 confirmed acute Q fever cases were notified over the study period. Cases decreased at a rate of 4.2% per annum (95% confidence interval (CI): 0.9, 7.4%). Notification rates decreased among abattoir workers and related occupations by 10.9% per annum (95% CI: 6.5, 15.0%), whereas those among dairy farmers rose by 14.9% per annum (95% CI: 4.7, 26.0%). The mean age of cases increased over the study period while the ratio of male to female cases decreased. Spatiotemporal analysis suggested endemic transmission, with 55% of cases associated with abattoirs and related businesses and a further 30% considered to have acquired the infection locally. In addition to abattoir-associated clusters, important foci for local acquisition included South and East Gippsland, Wodonga and an outbreak centred on a dairy goat farm west of Melbourne. CONCLUSIONS: There has been a reduction in cases of acute Q fever in Victoria over the past 20 years and a changing epidemiology with respect to age, sex and acquisition source. Epidemiological and spatiotemporal analyses suggested a low level of endemic transmission within the state, with multiple foci of increased zoonotic transmission.

Investigation of the Role of Campylobacter Infection in Suspected Acute Polyradiculoneuritis in Dogs.

BACKGROUND: Acute polyradiculoneuritis (APN) is an immune-mediated peripheral nerve disorder in dogs that shares many similarities with Guillain-Barré syndrome (GBS) in humans, in which the bacterial pathogen Campylobacter spp. now is considered to be a major triggering agent. Little information is available concerning the relationship between APN and Campylobacter spp. in dogs. HYPOTHESIS/OBJECTIVES: To estimate the association between Campylobacter spp. infection and APN. Associations with additional potential risk factors also were investigated, particularly consumption of raw chicken. ANIMALS: Twenty-seven client-owned dogs suffering from suspected APN and 47 healthy dogs, client-owned or owned by staff members. METHODS: Case-control study with incidence density-based sampling. Fecal samples were collected from each enrolled animal to perform direct culture, DNA extraction, and polymerase chain reaction (PCR) for detection of Campylobacter spp. In some cases, species identification was performed by sequence analysis of the amplicon. Data were obtained from the medical records and owner questionnaires in both groups. RESULTS: In cases in which the fecal sample was collected within 7 days from onset of clinical signs, APN cases were 9.4 times more likely to be positive for Campylobacter spp compared to control dogs (P < 0.001). In addition, a significant association was detected between dogs affected by APN and the consumption of raw chicken (96% of APN cases; 26% of control dogs). The most common Campylobacter spp. identified was Campylobacter upsaliensis. CONCLUSIONS AND CLINICAL IMPORTANCE: Raw chicken consumption is a risk factor in dogs for the development of APN, which potentially is mediated by infection with Campylobacter spp.

Diagnostic accuracy of pre-treatment biopsy for grading cutaneous mast cell tumours in dogs.

Mast cell tumours (MCTs) are common tumours of the canine skin, and are estimated to represent up to 20% of all skin tumours in dogs. Tumour grade has a major impact on the incidence of local recurrence and metastatic potential. In addition to helping the clinician with surgical planning, knowledge of the tumour grade also assists in proper prognostication and client education. For pre-treatment biopsies to be useful, there must exist a high level of correlation between the histopathological grade obtained from the pre-treatment biopsy and the actual histopathological grade from the excisional biopsy. The aim of this study was to determine concordance of tumour grade between various biopsy techniques (wedge, punch, needle core) and the "gold standard" excisional biopsy method. We found an overall concordance rate of 96% based on the Patnaik grading system, and an overall concordance rate of 92% based on the Kiupel grading system. The accuracy of the various biopsy techniques (wedge, punch and needle core) when compared with excisional biopsy was 92%, 100% and 100%, respectively, based on the Patnaik grading system, and 90%, 95% and 100%, respectively, based on the Kiupel grading system. Of the cases with discordant results, the pre-treatment biopsies tended to underestimate the grade of the tumour. Based on these results, we conclude that pre-treatment biopsies are sufficiently accurate for differentiating low-grade from high-grade MCTs, regardless of biopsy technique or tumour location.

A cross-sectional study to quantify the prevalence of avian influenza viruses in poultry at intervention and non-intervention live bird markets in central Vietnam, 2014.

In Vietnam, live bird markets are found in most populated centres, providing the means by which fresh poultry can be purchased by consumers for immediate consumption. Live bird markets are aggregation points for large numbers of poultry, and therefore, it is common for a range of avian influenza viruses to be mixed within live bird markets as a result of different poultry types and species being brought together from different geographical locations. We conducted a cross-sectional study in seven live bird markets in four districts of Thua Thien Hue Province in August and December, 2014. The aims of this study were to (i) document the prevalence of avian influenza in live bird markets (as measured by virus isolation); and (ii) quantify individual bird-, seller- and market-level characteristics that rendered poultry more likely to be positive for avian influenza virus at the time of sale. A questionnaire soliciting details of knowledge, attitude and avian influenza practices was administered to poultry sellers in study markets. At the same time, swabs and faecal samples were collected from individual poultry and submitted for isolation of avian influenza virus. The final data set comprised samples from 1,629 birds from 83 sellers in the seven live bird markets. A total of 113 birds were positive for virus isolation; a prevalence of 6.9 (95% CI 5.8-8.3) avian influenza virus-positive birds per 100 birds submitted for sale. After adjusting for clustering at the market and individual seller levels, none of the explanatory variables solicited in the questionnaire were significantly associated with avian influenza virus isolation positivity. The proportions of variance at the individual market, seller and individual bird levels were 6%, 48% and 46%, respectively. We conclude that the emphasis of avian influenza control efforts in Vietnam should be at the individual seller level as opposed to the market level.

Predictive modelling of Ross River virus notifications in southeastern Australia.

Ross River virus (RRV) is a mosquito-borne virus endemic to Australia. The disease, marked by arthritis, myalgia and rash, has a complex epidemiology involving several mosquito species and wildlife reservoirs. Outbreak years coincide with climatic conditions conducive to mosquito population growth. We developed regression models for human RRV notifications in the Mildura Local Government Area, Victoria, Australia with the objective of increasing understanding of the relationships in this complex system, providing trigger points for intervention and developing a forecast model. Surveillance, climatic, environmental and entomological data for the period July 2000-June 2011 were used for model training then forecasts were validated for July 2011-June 2015. Rainfall and vapour pressure were the key factors for forecasting RRV notifications. Validation of models showed they predicted RRV counts with an accuracy of 81%. Two major RRV mosquito vectors (Culex annulirostris and Aedes camptorhynchus) were important in the final estimation model at proximal lags. The findings of this analysis advance understanding of the drivers of RRV in temperate climatic zones and the models will inform public health agencies of periods of increased risk.

One Health approach to controlling a Q fever outbreak on an Australian goat farm.

A recent outbreak of Q fever was linked to an intensive goat and sheep dairy farm in Victoria, Australia, 2012-2014. Seventeen employees and one family member were confirmed with Q fever over a 28-month period, including two culture-positive cases. The outbreak investigation and management involved a One Health approach with representation from human, animal, environmental and public health. Seroprevalence in non-pregnant milking goats was 15% [95% confidence interval (CI) 7-27]; active infection was confirmed by positive quantitative PCR on several animal specimens. Genotyping of Coxiella burnetii DNA obtained from goat and human specimens was identical by two typing methods. A number of farming practices probably contributed to the outbreak, with similar precipitating factors to the Netherlands outbreak, 2007-2012. Compared to workers in a high-efficiency particulate arrestance (HEPA) filtered factory, administrative staff in an unfiltered adjoining office and those regularly handling goats and kids had 5·49 (95% CI 1·29-23·4) and 5·65 (95% CI 1·09-29·3) times the risk of infection, respectively; suggesting factory workers were protected from windborne spread of organisms. Reduction in the incidence of human cases was achieved through an intensive human vaccination programme plus environmental and biosecurity interventions. Subsequent non-occupational acquisition of Q fever in the spouse of an employee, indicates that infection remains endemic in the goat herd, and remains a challenge to manage without source control.

Costing the Morbidity and Mortality Consequences of Zoonoses Using Health-Adjusted Life Years.

Governments are routinely involved in the biosecurity of agricultural and food imports and exports. This involves controlling the complex ongoing threat of the broad range of zoonoses: endemic, exotic and newly emerging. Policy-related decision-making in these areas requires accurate information and predictions concerning the effects and potential impacts of zoonotic diseases. The aim of this article was to provide information concerning the development and use of utility-based tools, specifically disability-adjusted life years (DALYs), for measuring the burden on human disease (morbidity and mortality) as a consequence of zoonotic infections. Issues and challenges to their use are also considered. Non-monetary utility approaches that are reviewed in this paper form one of a number of tools that can be used to estimate the monetary and non-monetary 'cost' of morbidity- and mortality-related consequences. Other tools derive from cost-of-illness, willingness-to-pay and multicriteria approaches. Utility-based approaches are specifically designed to capture the pain, suffering and loss of functioning associated with diseases, zoonotic and otherwise. These effects are typically complicated to define, measure and subsequently 'cost'. Utility-based measures will not be able to capture all of the effects, especially those that extend beyond the health sector. These will more normally be captured in financial terms. Along with other uncommon diseases, the quality of the relevant epidemiological data may not be adequate to support the estimation of losses in utility as a result of zoonoses. Other issues in their use have been identified. New empirical studies have shown some success in addressing these issues. Other issues await further study. It is concluded that, bearing in mind all caveats, utility-based methods are important tools in assessing the magnitude of the impacts of zoonoses in human disease. They make an important contribution to decision-making and priority setting across all sectors. In doing so, they highlight the relative importance of the burden of zoonotic disease globally.

Horse owners'/managers' perceptions about effectiveness of biosecurity measures based on their experiences during the 2007 equine influenza outbreak in Australia.

Following the first ever equine influenza outbreak in Australia in 2007, a study was conducted involving 200 horse owners and managers to determine their perceptions about effectiveness of biosecurity measures and the factors associated with these perceptions. Face-to-face interviews were conducted with horse owners/managers to obtain information about their perceptions of the effectiveness of biosecurity practices, their sources of information about infection control during the outbreak and their horse industry involvement. Two outcome variables were created from horse owners' responses to a 17-item question on the perceived effectiveness of various recommended equine influenza biosecurity measures: (a) a binary outcome variable (Low/High biosecurity effectiveness) and (b) a continuous outcome variable (the proportion of the 17 measures considered 'very effective'). These outcomes were used in binomial logistic and linear regression analyses, respectively, to determine factors associated with perceptions of biosecurity effectiveness. Variables with a p-value <0.05 in multivariable models were retained in the final models. The majority (83%) of the 200 horse owners and managers interviewed believed that more than half of the recommended equine influenza biosecurity measures were very effective for protecting their horses from equine influenza infection in the event of a future outbreak. Interviewees that were more likely to judge on-farm biosecurity measures as effective were those who received infection control information from a veterinarian during the outbreak, did not experience equine influenza infection in their horses, and those on small acreage premises (homes with horses on site). Greater levels of preparedness for a future equine influenza outbreak and greater interest in information about infection control were associated with a better perception about effectiveness of biosecurity measures. This study identified factors associated with horse owners' and managers' perception of effectiveness of biosecurity measures. These findings should be considered in the design of infection control programs.

From the horse's mouth: perceptions of the management of the 2007 equine influenza outbreak in Australia.

In August 2007, Australia experienced its first-ever outbreak of equine influenza, a highly infectious respiratory disease of horses. Although the outbreak spread over a large geographic area, it was eradicated within 5 months following a substantial disease control effort led by federal and state animal health authorities. Despite its timely control, this large-scale outbreak caused severe impacts on horse owners and industry participants. This study aimed to describe the perceptions of horse owners and managers, impacted by outbreak control measures, regarding the state government's animal health authority outbreak management. Participants were interviewed face-to-face. Factors associated with ordinal ratings of perception ('well managed', 'adequately managed' and 'poorly managed') were identified using ordinal logistic regression. Factors significantly associated with a reduced likelihood of 'well-managed' outbreak response ratings, adjusted for age and gender, were being involved in horse competitions/sporting events (OR = 0.48; 95% CI: 0.25-0.91), managing a horse stud (OR = 0.09; 95% CI: 0.03-0.28) and believing that another outbreak of equine influenza was highly likely in the next 5 years (OR = 0.29; 95% CI: 0.12-0.68). Possible reasons for these ratings were further investigated using content analyses. Outbreak communications and government efficiency/support were mentioned most frequently as both strengths (30% and 28%, respectively) and weaknesses (40% and 30%, respectively) of the outbreak management. To promote manager-government rapport and future compliance with disease control regulations, we recommend that outbreak communications and outbreak information systems be reviewed.