[Emerging infectious diseases and the emergence of diseases: a conceptual revision and new issues].

Contrary to expectations concerning the eradication of infectious diseases, it has been emerged, diseases worldwide that were unknown to science or considered to be eradicated or under control by epidemiological surveillance services. In this paper we outline the emergent infectious diseases debate and analyze the concept spread through publications from the Centers for Disease Control and Prevention (CDC) of the United States and through human science point of view. The review of national and international literature suggests some ambiguities in the definition of the categories "new disease" and "emerging disease" and the differences between the concept of emerging infectious diseases and the study of the emergence of diseases. Whilst the first concept includes the study of specific infections and focuses the analysis on the organism affected, on the patient and on the human population; the second concept - less studied - encompasses the study of the epistemological dimensions of medical knowledge and the ecology of emerging infectious diseases. This concept focuses on the systemic level - on the ecosystem and populations of parasites and hosts (whatever the species) and on the socio-cultural behavior - and demands the integration of various academic disciplines.