Animal-related factors predicting fatal cases of blackleg and gas gangrene in cattle.

BACKGROUND: Blackleg and gas gangrene are acute clostridial infections primarily affecting cattle. The objectives of this study were to identify (i) animal-related factors influencing the occurrence and (ii) prognostic pathological findings supporting the differentiation of fatal blackleg and gas gangrene cases in the cattle population from 1998 to 2018 in Styria, Austria. METHODS: Two binomial logistic models were applied to analyse the research questions. Additionally, cross-validations were performed to estimate the accuracy of the predictive models. RESULTS: Model results show that animal-related factors (i.e., age, geographical discovery location of dead cattle, vaccination status) significantly influence the occurrence of blackleg when compared to gas gangrene. Pathological findings are similar for both diseases. CONCLUSIONS: Model results reveal that using animal-related factors has a better accuracy to predict the fatal cases caused by both pathogens. Thus, the authors recommend not relying on pathological findings as predictive factors in the differentiation between blackleg and gas gangrene in cattle.

Mapping the global prevalence of bovine viral diarrhoea virus infection and its associated mitigation programmes.

The aim of this study was to collect information on the global distribution of the prevalence of bovine viral diarrhoea virus (BVDV) and respective mitigation programmes, using a questionnaire and literature review to provide as complete a picture of the worldwide BVDV situation as possible. This study collated information on 107 countries with respect to mitigation activities and 88 countries regarding BVDV infections during the observation period (1960-2017). A heterogeneous epidemiological situation for both BVDV prevalence and the presence of mitigation programmes was observed. The results of this analysis could be used to increase the visibility of the distribution of BVDV, to provide supporting data for global animal disease databases and to assist veterinary public health authorities in the decision-making processes to establish mitigation activities.

A meta-analysis of bovine viral diarrhoea virus (BVDV) prevalences in the global cattle population.

A random effect meta-analysis was performed to estimate the worldwide pooled bovine viral diarrhoea virus (BVDV) prevalences of persistently infected (PI), viraemic (VI) and antibody-positive (AB) animals and herds. The meta-analysis covered 325 studies in 73 countries that determined the presence or absence of BVDV infections in cattle from 1961 to 2016. In total, 6.5 million animals and 310,548 herds were tested for BVDV infections in the global cattle population. The worldwide pooled PI prevalences at animal level ranged from low (≤0.8% Europe, North America, Australia), medium (>0.8% to 1.6% East Asia) to high (>1.6% West Asia). The PI and AB prevalences in Europe decreased over time, while BVDV prevalence increased in North America. The highest mean pooled PI prevalences at animal level were identified in countries that had failed to implement any BVDV control and/or eradication programmes (including vaccination). Our analysis emphasizes the need for more standardised epidemiological studies to support decision-makers implementing animal health policies for non-globally-regulated animal diseases.

Cost distribution of bluetongue surveillance and vaccination programmes in Austria and Switzerland (2007-2016).

Bluetongue virus (BTV) is an emerging transboundary disease in Europe, which can cause significant production losses among ruminants. The analysis presented here assessed the costs of BTV surveillance and vaccination programmes in Austria and Switzerland between 2007 and 2016. Costs were compared with respect to time, type of programme, geographical area and who was responsible for payment. The total costs of the BTV vaccination and surveillance programmes in Austria amounted to €23.6 million, whereas total costs in Switzerland were €18.3 million. Our analysis demonstrates that the costs differed between years and geographical areas, both within and between the two countries. Average surveillance costs per animal amounted to approximately €3.20 in Austria compared with €1.30 in Switzerland, whereas the average vaccination costs per animal were €6.20 in Austria and €7.40 in Switzerland. The comparability of the surveillance costs is somewhat limited, however, due to differences in each nation's surveillance (and sampling) strategy. Given the importance of the export market for cattle production, investments in such programmes are more justified for Austria than for Switzerland. The aim of the retrospective assessment presented here is to assist veterinary authorities in planning and implementing cost-effective and efficient control strategies for emerging livestock diseases.

How much confidence do we need in animal experiments? Statistical assumptions in sample size estimation.

Statistical sample size calculation is a crucial part of planning nonhuman animal experiments in basic medical research. The 3R principle intends to reduce the number of animals to a sufficient minimum. When planning experiments, one may consider the impact of less rigorous assumptions during sample size determination as it might result in a considerable reduction in the number of required animals. Sample size calculations conducted for 111 biometrical reports were repeated. The original effect size assumptions remained unchanged, but the basic properties (type 1 error 5%, two-sided hypothesis, 80% power) were varied. The analyses showed that a less rigorous assumption on the type 1 error level (one-sided 5% instead of two-sided 5%) was associated with a savings potential of 14% regarding the original number of required animals. Animal experiments are predominantly exploratory studies. In light of the demonstrated potential reduction in the numbers of required animals, researchers should discuss whether less rigorous assumptions during the process of sample size calculation may be reasonable for the purpose of optimizing the number of animals in experiments according to the 3R principle.

A systematic worldwide review of the direct monetary losses in cattle due to bovine viral diarrhoea virus infection.

Bovine viral diarrhoea virus (BVDV) is an important infectious agent of cattle worldwide that affects herd productivity and reproduction. In this systematic review of the impact of BVDV, studies were analysed with a particular focus on the monetary implications and types of direct losses, the initial infection status of herds, production systems, time periods of assessment, calculation level, study types and whether or not country-specific assessments were published. A linear mixed model was applied to analyse factors that influence the level of monetary direct losses due to BVDV infection. The 44 studies included in this review covered 15 countries and assessed direct monetary losses due to BVDV incurred over the past 30 years. Direct losses between and within countries were largely heterogeneous with respect to the monetary level and types of direct losses, ranging from 0.50 to 687.80 US dollars (USD) per animal.1 Average direct losses per naïve dairy cow were USD24.85 higher than per beef cow. Country-specific assessments of direct losses due to BVDV were provided in 38/44 (86.4%) studies. Mortality, morbidity, premature culling, stillbirths, abortion, reinfection, country and study type had a significant influence on the monetary level of direct losses (r2 = 0.69). Countries recording direct losses were more likely to carry out voluntary or compulsory control and eradication programmes (odds ratio = 10.2; 95% confidence interval 1.7-81.9; P = 0.004).

A systematic review of financial and economic assessments of bovine viral diarrhea virus (BVDV) prevention and mitigation activities worldwide.

Infection with bovine viral diarrhea virus (BVDV) results in major economic losses either directly through decreased productive performance in cattle herds or indirectly, such as through expenses for control programs. The aim of this systematic review was to review financial and/or economic assessment studies of prevention and/or mitigation activities of BVDV at national, regional and farm level worldwide. Once all predefined criteria had been met, 35 articles were included for this systematic review. Studies were analyzed with particular focus on the type of financially and/or economically-assessed prevention and/or mitigation activities. Due to the wide range of possible prevention and/or mitigation activities, these activities were grouped into five categories: i) control and/or eradication programs, ii) monitoring or surveillance, iii) prevention, iv) vaccination and v) individual culling, control and testing strategies. Additionally, the studies were analyzed according to economically-related variables such as efficiency, costs or benefits of prevention and/or mitigation activities, the applied financial and/or economic and statistical methods, the payers of prevention and/or mitigation activities, the assessed production systems, and the countries for which such evaluations are available. Financial and/or economic assessments performed in Europe were dominated by those from the United Kingdom, which assessed mostly vaccination strategies, and Norway which primarily carried out assessments in the area of control and eradication programs; whereas among non-European countries the United States carried out the majority of financial and/or economic assessments in the area of individual culling, control and testing. More than half of all studies provided an efficiency calculation of prevention and/or mitigation activities and demonstrated whether the inherent costs of implemented activities were or were not justified. The dairy sector was three times more likely to be assessed by the countries than beef production systems. In addition, the dairy sector was approximately eight times more likely to be assessed economically with respect to prevention and/or mitigation activities than calf and youngstock production systems. Furthermore, the private sector was identified as the primary payer of prevention and/or mitigation activities. This systematic review demonstrated a lack of studies relating to efficiency calculations, in particular at national and regional level, and the specific production systems. Thus, we confirmed the need for more well-designed studies in animal health economics in order to demonstrate that the implementation and inherent costs of BVDV prevention and/or mitigation activities are justified.