The Munich Hygienist Who Drank a Cholera Flask in 1892 to Prove Koch Was Wrong

Max von Pettenkofer (1818–1901) was the dominant German public-health figure of the second half of the 19th century. He held the chair of hygiene at the University of Munich from 1865, was personal physician to the Bavarian royal court for thirty years, was ennobled in 1883, and built Munich’s water and sewage systems on principles that had substantially eliminated cholera mortality in the city by 1880. His authority on cholera was approximately the highest of any single individual in continental European medicine.

He was also substantively wrong about what caused cholera.

What Pettenkofer believed

Pettenkofer’s published cholera theory was a localist one. Cholera, he argued, was not transmitted directly from person to person through contaminated water (the view that the English physician John Snow had developed in the 1850s and that Robert Koch’s identification of Vibrio cholerae in 1883 had appeared to confirm). Cholera was instead, in Pettenkofer’s framework, a place-based phenomenon: the disease required specific local soil-and-groundwater conditions to develop into an active epidemic form, and the cholera agent could not become pathogenic without those conditions. The same water could carry cholera bacteria into one city and produce no epidemic, then into another city and produce a catastrophic outbreak. The substantive variable was the local soil hygiene.

The theory had been built on Pettenkofer’s substantial empirical work in Munich itself, where cholera epidemics had progressively declined through the 1860s and 1870s in close parallel with the city’s water and sewage infrastructure improvements. The improvements had substantively changed the local soil hygiene; the cholera had substantively stopped; the theory appeared confirmed.

The 1892 confrontation

The Hamburg cholera epidemic of August–October 1892 killed approximately 8,600 people. The epidemic was substantively confined to Hamburg, while the directly-adjacent Prussian city of Altona (with shared water sources but different filtration) had almost no cases. The epidemiological pattern was substantively a vindication of the contaminated-water theory and of Koch’s specific institutional position.

Pettenkofer was not satisfied. He requested and received a flask of Vibrio cholerae culture from Koch’s institute in Berlin — the standard Koch laboratory preparation, isolated from a Hamburg patient and confirmed by microscopic examination. On 7 October 1892, at his Munich institute, Pettenkofer drank the contents of the flask in the presence of witnesses. His junior colleague Rudolf Emmerich drank a second flask.

Pettenkofer was 74. He did not die. He had no significant illness. (Emmerich developed a substantive case of diarrhoea and was bedridden for several days but also did not die.) Pettenkofer published the result as a substantive disproof of the Koch theory.

What had actually happened

The modern epidemiological reading is that both men were probably substantively protected by stomach acidity (which kills most ingested Vibrio cholerae before they can reach the small intestine) and by the relatively small infectious doses involved. Roughly half of infections with Vibrio cholerae are asymptomatic or produce only mild diarrhoea; the catastrophic clinical cholera that produces death by dehydration in untreated cases occurs in only a fraction of exposures. The flask experiment substantively showed nothing about the truth or falsity of the contaminated-water theory — it showed only that Pettenkofer and Emmerich were not in the unlucky fraction.

The substantive scientific consensus had nonetheless moved decisively against Pettenkofer by the mid-1890s. The Hamburg epidemic was the largest demonstration; the parallel epidemiological pattern of the broader 1817-onward cholera pandemics was substantially consistent with water transmission rather than soil-localist mechanisms; and Koch’s bacteriological framework was substantively winning the institutional politics of European public health.

The suicide

Pettenkofer retired from his Munich professorship in 1894 and progressively withdrew from public scientific life. His clinical depression appears to have developed in the late 1890s, possibly as a delayed consequence of the substantive intellectual collapse of his life’s theoretical framework. He shot himself in his Munich apartment on 10 February 1901, aged 82.

The Italian anatomist Filippo Pacini — who had identified Vibrio cholerae under the microscope in Florence in 1854, 29 years before Koch, and had been ignored by the European medical establishment in part because Pettenkofer’s localist framework had dominated the period — had died in obscurity in 1883, the same year Koch’s announcement vindicated his work.

The Pettenkofer–Koch dispute was the last defence of pre-bacteriological public-health theory in continental Europe. The dispute substantively ended with Pettenkofer’s death.