Zymotic diseases an obsolete term in medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, 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

William Farr

William Farr was a nineteenth-century British epidemiologist, regarded as one of the founders of medical statistics.-Early life:He was born in Kenley, Shropshire, England to poor parents...

, of the British Registrar-General's department

General Register Office

The General Register Office for England and Wales is the section of the UK Identity and Passport Service responsible for the civil registration of births , adoptions, marriages, civil partnerships and deaths in England and Wales and for those same events outwith the UK if they involve a UK citizen...

, 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

Typhus

Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters...

 and typhoid fever

Typhoid fever

Typhoid fever, also known as Typhoid, is a common worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella enterica, serovar Typhi...

s, smallpox

Smallpox

Smallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple"...

, scarlet fever

Scarlet fever

Scarlet fever is a disease caused by exotoxin released by Streptococcus pyogenes. Once a major cause of death, it is now effectively treated with antibiotics...

, measles

Measles

Measles, also known as rubeola or morbilli, is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses...

, erysipelas

Erysipelas

Erysipelas is an acute streptococcus bacterial infection of the deep epidermis with lymphatic spread.-Risk factors:...

, cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

, whooping-cough, diphtheria

Diphtheria

Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...

, &c.). The science of bacteriology

Bacteriology

Bacteriology is the study of bacteria. This subdivision of microbiology involves the identification, classification, and characterization of bacterial species...

 has displaced the old fermentation theory

Fermentation theory

The fermentation theory of disease is the concept that many diseases, including the diseases which were "epidemic, endemic and contagious", owe 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...

, 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.