Cholera, canals, and contagion: Rediscovering Dr Beck's report

Cholera remains a major global public health threat. A severe diarrheal illness, caused by toxigenic strains of Vibrio cholerae, cholera is endemic throughout much of the world,¹and causes sporadic outbreaks in regions with inadequate access to safe drinking water and sanitation.^2, 3 Even in the modern era, cholera can have a case-fatality rate in the range of 14 to 23 per cent.^4, 5 Cholera has pandemic potential: antigenic shifts in dominant V. cholerae strains are associated with the emergence of global epidemics with high case-fatality rates. The seventh known cholera pandemic started in 1961 and is still ongoing. The causative organism, V. cholera O1 biotype El Tor, has replaced the classical strain as the leading cause of endemic cholera worldwide.⁶ As events in Haiti in the autumn of 2010 have demonstrated, lack of universal access to clean water and sewage treatment in low-income countries means that this disease remains a major public health priority.^7, 8

While cholera continues to be a major source of mortality in low- and low-middle income countries, it may also threaten higher income countries via disease importation.^6, 9 Khan and colleagues have recently commented on continued importance of global ‘connectedness’ to disease emergence and spread, particularly given modern air travel.¹⁰A single person with the disease may spark a local epidemic in an area previously free of that pathogen. Travelers import cholera into Canada and the United States with some frequency (<12 cases per year between 1996 and 2007)¹¹ but the relative wealth of water- and sewage-treatment infrastructure in these countries appears to limit epidemic spread.¹²

Travel's role in diffusion of infectious diseases predates air travel. Indeed, the way infectious disease epidemics spread tells much about indirect connections between populations with little awareness of one another's existences. Fenn, for example, demonstrated that smallpox epidemics in the late eighteenth century showed a network of contacts spanning the American continent decades before Lewis and Clark's cross-continental expedition.¹³ Late nineteenth-century American disease control experts recognized the importance of travel and transit in the genesis of cholera epidemics. In their efforts to forestall or prevent cholera epidemics in US cities, they focused on Hamburg, then a major embarkation point for people crossing the Atlantic.¹⁴

Recognition by mainstream medical practitioners of the transmissibility of cholera emerged largely from John Snow's work on London cholera epidemics of the 1840s and 1850s,^15, 16, 17 and lagged behind the widespread popular belief that the disease was contagious.¹⁸ During the cholera epidemics of the early nineteenth century, physicians in Europe and North America disparaged fear of contagion as superstition. They admonished the public to attend to its ‘moral constitution’ to prevent disease. As Richardson notes, cholera was ‘hardly regarded as a biological entity but a means of retribution upon the morally suspect’¹⁹ –a product of the interaction between a corrupted atmosphere (a ‘miasma’) and exciting characteristics in the victim. Drunkenness, gluttony, sexual depravity, and any other form of ‘intemperance’, were held to increase vulnerability to cholera,^20, 21 as were both fear of cholera²² and lack of fear of cholera.²³

Economic liberalism, prevalent in professional classes, may have encouraged physicians to disparage the notion of cholera as contagious. Designating cholera as contagious would have, as a corollary, implied that disruption of trade and travel with via quarantine would be necessary to control the disease.^24, 25 State-directed disruption of individuals’ economic activities was unattractive to an emerging and increasingly independent-minded professional and merchant class.^24, 25

We discuss a document about the 1832 cholera epidemic, presenting geospatial data that imply cholera's contagiousness. These data might have allowed the report's author to intuit the transmissibility of cholera well in advance of Snow. And we explore the social context that led the report's author to disbelieve his own observations and favor a medical model inconsistent with his data.

Source: Journal of Public Health http://www.palgrave-journals.com/jphp/journal/v32/n3/full/jphp201120a.html

Keywords: health supplies, health article, health articles, hospital equipment, equipment for hospital, health information, Cleanliness, information about health,