The history of the idea of transmission, from its earliest murmurs, resembles that of other scientific concepts that have borrowed from everyday speech: at the beginning, we have all the wealth and confusion of the particular, which is governed more by emotion than by precise meaning; at the end of the analysis, we arrive at a strictly defined and somewhat abstract concept: despite the questionable tendency towards anachronism represented by the ambiguous stability of the word, a completely new meaning is formed by the spirit of the scientist for his own needs, which are no longer the same as those of popular sensitivity.
Depending on the political and social context, the concepts of infectious transmission and infection oppose or combine with each other, are used by particular interests or mobilized to serve a public health policy, while incorporating the shifts brought about by advances in scientific knowledge.