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""On Darwin, Snow, and Deadly Diseases.""

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(June 1994)Natural History (June 1994): 42-45

PDF from photocopy; Michigan State University Libraries.

Ewald reveals the process of his thinking about a vexing problem: "why some diseases are so dangerous and others merely annoyances" (42). He concludes that "the lethality of the various diarrheal bacteria correlated almost perfectly with their tendencies to be waterborne. The correlation explained why cholera, typhoid fever, and some kinds of dysentery were so severe. It also suggested a new dimension for disease control. If waterborne transmission favors the evolution of increased harmfulness, then water purification should do the opposite--transform severe pathogens into milder ones" (44). He then ruminates on Snow and Darwin inhabiting the same part of London, although there is no evidence that they ever met or knew what the other was working on. [PVJ]

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