Not a Fact Anymore
DE

Not a fact anymore

Cholera is caused by poisonous miasma, or bad air, arising from filth and decay.

What we know now

Cholera is an intestinal infection caused by toxigenic strains of the bacterium Vibrio cholerae, usually acquired through contaminated food or water.

Why it changed

Outbreak patterns linked disease to particular water supplies, microscopy identified the organism, and later bacteriological work established the causal role of Vibrio cholerae.

Status
Overturned
Category
Medicine
Accepted for
≈39 years
Accepted approximately
Early to mid-19th century
Changed approximately
1850s–1880s
John Snow’s 1854 map of Soho showing cholera deaths as stacked black bars along streets. The heaviest concentration of marks is around the Broad Street area near the contaminated water pump.

John Snow’s 1854 map plots cholera deaths as stacked black bars along Soho’s streets. The dense concentration around Broad Street supported his case that the outbreak was linked to contaminated water rather than poisonous air; the map was one part of a broader investigation.

John Snow, 1854Wikimedia Commons: View source ↗Public domain / no known restrictions

Bad sanitation really was associated with cholera, which helped miasma theory appear persuasive. The causal pathway, however, was contaminated water and food rather than poisonous air.

John Snow’s work was important but did not single-handedly produce immediate acceptance. Filippo Pacini identified the cholera organism in 1854, and Robert Koch later isolated and studied it during the 1880s.

Evidence

Sources and what they establish

Historical context

  • 150th Anniversary of John Snow and the Pump HandleU.S. Centers for Disease Control and Prevention

    Explains that Snow's waterborne theory was unpopular compared with the prevailing miasma explanation and summarizes his Broad Street investigation.

  • John Snow InvestigationU.S. Centers for Disease Control and Prevention

    Describes Snow's mapping and investigation of the 1854 London cholera outbreak.

Current evidence

  • CholeraWorld Health Organization

    Identifies cholera as an acute diarrhoeal infection caused by ingestion of food or water contaminated with Vibrio cholerae.

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Around 1854

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