Statistical methods in veterinary epidemiology

Résumé

The main aim of veterinary epidemiology is to increase knowledge on both i) the dynamics and impact of diseases on animal production, health and welfare and on ii) the risk of animal-acquired (i.e. zoonoses) and food-borne diseases in humans. Because animals and animal products are the source of income for a large sector of society, the emphasis on economic aspects is much more important in veterinary epidemiology than in human epidemiology. Typical research questions deal with the identification of risk factors for a disease, the estimation of the impact of a disease on production, the evaluation of the efficacy of a treatment or the timely identification of disease occurrence. For these purposes, a wide range of statistical techniques are used and several types of data sources exist. One peculiarity in animal productions is the collection of large production related data such as daily milk productions, live weights or reproduction data for example. These extremely large databases are both an asset and a challenge for statistical modelling. To illustrate the data sources and statistical methods used in veterinary epidemiology, we present part of the work conducted following the emergence of the bluetongue virus in cattle in 2006. First, we show how the impacts of the disease on milk production and reproduction were estimated. Then, in order to improve the timeliness of detection of such emergences, the application of syndromic surveillance methods to the bluetongue emergence is presented. Finally, some knowledge gaps and directions for future work are presented.