Résumé
Epidemiologists and parasitologists studying transmissible diseases tend to take an interest in direct causes, the visible modes of spread, and disease prevention. Usually, these disciplines show little interest in the physical, ecological, or evolutionary processes which occur on larger time and space scales. Epidemiologists and parasitologists have for a long time also considered the individual host as the only frame of reference for understanding the causes and consequences of infections. However, recent studies on the impact of global environmental changes and the dynamics of pathogens and their geographical distributions perfectly illustrate the relevance of large-scale studies for a better understanding of the persistence and dynamics of micro-organisms in host populations of humans, animals, or plants.