ABSTRACT
The coming of the laboratory radically transformed the identity of infectious disease. This is one of the least appreciated – and, indeed, least obvious –of the changes of thinking and practice brought about in medicine by the coming of the laboratory. The history of medicine as conventionally written is based on the assumption of a simple continuity in the identity of diseases, and thus tends to make invisible the issues which are actually involved in speaking of the ‘identity’ of a disease. The role of the laboratory in all this is absolutely crucial. The laboratory today holds total authority on the authentication of plague, for the final diagnosis – the identification – is impossible without the laboratory. So much so is this the case that even if a patient appears to have all the symptoms of plague, yet they cannot be said to have plague until the laboratory has spoken.
