Come si sviluppa e come si esaurisce una pandemia? Una storia naturale e sociale

The scientific revolution linked to the names of Louis Pasteur and Robert Koch has profoundly changed the way we understand, define and control communicable diseases, thanks to the affirmation of a causal link between the specificity of a given germ and a specific disease. As a result of the interaction between different forms of life, infectious diseases are biological processes and therefore have a natural history, with an origin, a life and a death. The spread of epidemics over time and space is the subject of numerous historical and epidemiological researches. In the last few decades the origin of diseases and their emergence have been studied extensively, but little has been understood about their disappearance. This article, in addition to suggesting the way to better understand the causal mechanisms of the emergence of a communicable disease, provides some historical examples of the disappearance of contagious diseases, questioning the causes of these phenomena.