Zymotic disease

Zymotic diseases (for the Greek language term zumoun for "ferment"), an obsolete term in medicine, formerly applied to the class of acute infectious maladies, presumed to be due to some virus or organism which acts in the system like a ferment. Note: This term was obsolete even in 1911, the date of the original version of the text below:

As originally employed by Dr W. Farr, of the British Registrar-General's department, the term included the diseases which were "epidemic, endemic and contagious," and were regarded as owing their origin to the presence of a morbific principle in the system, acting in a manner analogous to, although not identical with, the process of fermentation. A large number of diseases were accordingly included under this designation. The term, however, came to be restricted in medical nomenclature to the chief fevers and contagious diseases (e.g. typhus and typhoid fevers, smallpox, scarlet fever, measles, erysipelas, cholera, whooping-cough, diphtheria, &c.). The science of bacteriology has displaced the old fermentation theory, and the term has practically dropped out of use.

From an old 1911 encyclopedia

Zyme or microzyme was the name of a germ presumed to be the cause of zymotic diseases.

This term was used extensively in the English Bills of Mortality as a cause of death from 1842, and ceased to be used in the early 1900s. Robert Newstead used this term in a 1908 publication in the Annals of Tropical Medicine and Parasitology, to describe the contribution of house flies (Musca domestica) towards the spread of infectious diseases.