Foundations of Early Bacteriology


his acute clinical observations as shown by his firsthand descriptions
of diseases such as scarlet fever, measles, and gout, Sydenham was
perplexed over the rise and fall of great epidemics, a state of mind in
which we still share. Unfortunately he reverted to a metaphysical
explanation an "epidemic constitution of the atmosphere" varying
with
the year and dependent "upon a secret and inexplicable alteration in
the
bowels of the earth." The planets were also brought into the confused
picture. Sydenham was thoroughly imbued with the miasmatic doc-
trine and includes "effluvia or seminia" in his discussions, but
he paid
little attention to the idea of infection or contagion. For example, he
thought that in the absence of a suitable epidemic constitution of the
air, plague could only be communicated by infection sporadically.
  In the study and isolation of an infectious agent, large size and ease
of demonstration have always been important aids to investigators.
Redi in 1668 showed evidence that a specific dermatitis was caused by
the body louse; Sarcoptes scabei was strongly implicated in the itch
(scabies) by Bonomo in 1687; and the disease was actually reproduced
experimentally in man a century later by Wichmann in 1786. Indeed
the itch mite had been described by Avenzoar as early as 1281, although
his writings are known only in translation. Linnaeus (i758) suggested
the probable relation of a number of helminths such as Ascaris lumbri-
coides and Taenia solium and the human diseases now known to be
caused by these worms.
  Agostino Bassi in 1835, demonstrated that a fungus, later named for
him, Botrytis bassiana was the causative agent in muscardine, a devastat-
ing disease of silkworms. Bulloch3° states that "he is justly regarded
as the real founder of the doctrine of pathogenic microorganisms of
vegetable origin." And in 1839, J. L. Schoenlein identified a fungus,
Achorion schoenleinii, as the cause of favus, a disease of the scalp of man.
  A road-breaking cogent essay by Henle80 (1840) using knowledge
available at the time in human and veterinary medicine as well as in
plant diseases, without adding any experimental evidence, showed that
living reproducing microorganisms provided the most plausible ex-
planation of the origin of many contagious diseases. Drawing especially
on two diseases of known etiology, scabies and muscardine, and many
contagious diseases of unknown etiology, Henle stressed the difficulties
in determining whether an agent or body found in a given disease is
actually the causative agent.


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