Miasma Theory of Disease

The miasma theory of disease causation has some incipient roots in Greek and Roman medicines, in particular in Hippocrates's “On Airs, Waters, and Places.” It developed as a naturalistic theory during the Renaissance and was especially popular in the 19th century to explain yellow fever, malaria, typhus, tuberculosis, cholera, and other diseases. According to this theory, disease causation relates to environmental emanations (gases), or miasmas. Miasmas are infectious noxious vapors emanated from putrefying carcasses, rotting vegetation or molds, and invisible dust particles inside dwellings. The understanding was that in some cases the air became attacked by an epidemic influence that became malignant after interaction with the emissions of organic decomposition from the earth.

However, in the early 19th century, it was clear that some diseases (e.g., yellow fever) did not develop if the person suffering from an infectious disease changed location. This fact enhanced the theory of miasma based on the presumed connection of the disease with a certain place, although it also propelled a search for other reasons. Professor François Magendie's lecture at the College of France in 1834 provides an example of how miasmatic disease was defined in early 19th century:

Later it was clarified that the cause of yellow fever as an acute disease was mosquitoes and that explained why changing places had a preventive health effect. By the mid-1800s, the concept of miasmas was intimately connected with theories of fermentation (so-called spirituous fermentation, acetic fermentation, lactic fermentation, [Page 540]and putrefication). Despite the invention of the microscope in the 1600s, fermentation was not anchored in these theories to microorganisms and the common belief was that chemical rather than biological processes caused fermentation. The miasma theory of disease postulated a sort of airborne “ferment”—the cholera epidemic was explained by such factors as calm, stagnant, high barometric pressure weather and high river water temperatures at night.

In the later part of the 19th century, the miasma theory competed with germ theory and helped prevent a quicker recognition of the latter. It is a lesson for the history of science, since William Farr, the advocate of the miasma theory, demonstrated one of the typical characteristics of narrow-minded authorities—insistence on one thesis and ignoring all others. However, even in the early 19th century, there were specialists who did not connect cholera to miasma.

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