THE BIOLOGY BOOK

Miasma Theory

Giovanni Maria Lancisi (1654–1720), William Farr (1807–1883), John Snow (1813–1858), Florence Nightingale (1820–1910), Robert Koch (1843–1910)

1717

Although references appear in ancient Greek writings, the miasma (or miasmatic) theory of infectious diseases originated during the Middle Ages and continued to enjoy favor in Europe, India, and China until the late nineteenth century. According to this theory, vapor, mist, or noxious air originating from decomposing organic matter (miasmata), entered the body and caused such diseases as cholera, the Black Death (bubonic plague), typhoid, tuberculosis, and malaria (“bad air”). During the black plagues in Europe, plague doctors would visit their patients garbed in goggles, protective clothing, and a hood with a long beak filled with perfumes to combat the odors of decayed flesh. During this time, sewage was removed and discarded far from the city and swamps drained to eliminate foul odors.

In his 1717 work, On the Noxious Effluvia of Marshes, the Italian epidemiologist and physician to popes, Giovanni Lancisi, described a correlation between the presence of mosquitoes and prevalence of malaria and offered what is arguably the most articulate description of the miasma theory. During the early 1850s, a cholera pandemic beset London that was concentrated in undrained, filthy, odoriferous areas near the banks of the River Thames that were inhabited by the poor. The medically trained William Farr, serving as the assistant commissioner for the 1851 London census, attributed the transmittal of cholera to noxious air. He was supported by Florence Nightingale, social reformer and founder of modern nursing, who advanced the cause of sanitary and fresh-smelling hospitals. By contrast, physician and epidemiologist John Snow, while not knowing the cause of cholera (the germ theory had yet to be formulated), rejected the miasma theory. By finding clusters of cases, Snow convincingly traced the source of the 1854 cholera outbreak in Soho, central London, to a contaminated water source.

Support for the miasma theory of disease dissipated after German physician Robert Koch’s rediscovery of the cholera bacterium (1882) and formulation of the germ theory of disease (1890). Although the miasma theory was discarded, it led to greater emphasis on public health and the construction of sanitation facilities, and swamps and marshes were drained for malaria control.

SEE ALSO: Germ Theory of Disease (1890), Endotoxins (1892), Malaria-Causing Protozoan Parasite (1898).

This image of a plague doctor appears in a 1721 work by Jean-Jacques Manget (1652–1742), a physician and writer from Geneva.