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This was even more obvious at that time, since the Sanitary Movement had succeeded in

improving sanitation and hygiene, and as a result the strength of the epidemics was

diminished. At the end of the 19


century Louis Pasteur detected the bacillus causing anthrax

(1877) and Robert Koch the germ causing tuberculosis (1879). Since the miasma theory was

meant to be valid for epidemics, the redetection of Vibrio cholerae by Robert Koch (1883)

dealt it a deadly blow. Even so, still the leading scientists of that time such as Max von

Pettenkofer, a professor of hygiene in Bavaria, were still unwilling to give in so easily and

acknowledge that the theory was incorrect

4 .

It is not always the big shots in a scientific field who come up with a breakthrough in

pushing science to new frontiers. Pettenkofer had his merits in supporting hygiene, and, even

though the miasma theory was not true, hygienic measures nevertheless helped to prevent

infectious diseases. Very often there are outsiders who usher science into a new age, such as

John Snow did decades before proof was available that the germ theory is correct.

The ‘CV’ of John Snow

Snow was born into a family of eight children in the English city of York on the 15


of March, 1813. His father was a coal yard worker. At 14 years of age he started work as an

apprentice surgeon-apothecary in Newcastle with Dr. William Hardcastle and continued to do

so until 1833. It was in Newcastle where the first cholera epidemic in the UK occurred and

where Snow attended cholera patients on behalf of Dr. Hardcastle. He studied medicine in

London, became a physician in 1843, and then worked as a general practitioner in the Soho

area. His research interest centred first on the physiology of the respiratory system and the

asphyxia of newborns. Because of his interest in issues of respiration, he attended a

demonstration of ether anaesthesia in 1846. He quickly moved the development of anaesthesia

further on by working with chloroform as well as ether. He became the leading authority on

this in the UK. In obstetrics he administered chloroform in such a way that the pain of giving

birth was reduced, but the women still remained conscious. Anaesthesia had little negative

effects on labour and actually seemed to accelerate it. Queen Victoria had nine children, and

Snow assisted the Queen with the birth of her 8


(Prince Leopold 1848) and 9



Beatrice 1857) children. The medical establishment originally opposed Snow’s attempts to

help, but it’s probable that the husband of Queen Victoria, Prince Albert, was interested in

using this method for his wife’s sake

5 .

Obviously, Snow was a man interested in a number of different fields of science. He

had an ‘analytical mind that thrived on details that others overlooked

6 .

This gift led him to be

known as ‘the father of epidemiology’ while investigating the transmission of cholera when

the disease reappeared during 1848 in London. Snow was already suspicious about the

possible falsity of the miasma theory, and this was based on his observations when he

witnessed the cholera epidemic during 1831 in Newcastle, a city in the midst of a mining area.


Nowadays the miasma theory could be considered as a ‘classical’ example of a confounder. A potential

confounder (here, bad air) is associated with the disease in the absence of exposure (water contaminated with

Vibrio cholerae

). The disease is associated with exposure (unhygienic conditions with bad air) but does not arise

as the consequence of the exposure (bad air).

5 (

retrieved 25.05.2015)


David Wachon: Old News 16 (8), 8-10, May & June, 2005