In current nosology, diseases are categorized as degen­erative, malignant, genetic, endocrine, and so on.

For purposes of the history of diseases we must add a cate­gory that we might term ephemeral. This requires a bit of literary license, because many conditions that fall in the class of ephemeral diseases had a longer ex­istence than that word usually implies. Ephemeral diseases comprise a large number of entities that car­ried working diagnostic names for earlier physicians (see, e.g., typhomalarial fever), but that are no longer recognized, at least by their previous names (Straus 1970; Hudson 1977a; Jarcho 1980).