[The causes of the emergence of infectious diseases]

The most infectious diseases that veterinarians and doctors believed to have vanquished in the 1980s in developed countries, have repeatedly talked about them in an often dramatic way in the 2000s. Foot-and-mouth disease devastated British herds in 2001, bovine tuberculosis, which had been hoped for eradication after 50 years of fighting, has re-emerged in the United Kingdom and France... At the same time, new infectious diseases, often zoonotic, have appeared in animals and in humans : HP avian influenza H5N1 in 2003, SARS in 2003, the MERS-CoVin2012…The reasons for these emergences are multiple because each disease has its own determinants. However, three main groups of factors can be cited: the evolution of pathogens (RNA viruses in particular), environmental changes favoring the development of vectors and reservoirs, and human behavior. The constant movement of humans, animals and their products on the planet, densification of populations and massive displacements linked to conflicts are probably at the heart of these evolutions.For the future, the challenges are to understand the infectious risks linked to these evolutions in order to try to prevent them. Epidemiology through surveillance and investigation will be tomorrow more than ever, at the heart of the prevention of infectious diseases.