Germ Theory and Disease in the 19th Century


Cholera:
Caused by bacteria that damage the intestinal lining, causing severe watery diarrhea (up to 4 gallons of fluid a day are lost). Spread by polluted water, in areas where sanitation is poor. Victims become extremely thirsty, vomit intermittently, and have muscle cramps.

Tuberculosis:
Bacterial disease usually attacks the lungs, spreads to other parts including brain, kidneys, and bones. Destroys the tissues, leading to death if not treated. Also called "consumption" and "scrofula." The "white plague of mankind."

Typhoid fever:
Bacterial disease spread under unsanitary conditions either from person to person or through contaminated food or water. Some people carry the bacteria in their bodies and infect others. Symptoms include headache, red rashes, vomiting, followed by fever, chills, weakness, diarrhea, and delirium. Can lead to gastrointestinal bleeding or rupture of the intestines. Also called "enteric fever."

Typhus:
Disease caused by microorganisms, especially carried by fleas, lice, and mites. Symptoms include severe headache, high fever, depression, delirium, and red rashes. Also called "prison fever."



Dr. John Snow
Diseases which are communicated from person to person are caused by some material which passes from the sick to the healthy, and which had the property of increasing and multiplying in the systems of the persons it attacks.
(On the Mode of Communication of Cholera, 1855)

Dr. William Budd
1. That typhoid fever is, in its essence, a contagious, or self-propagating fever, and is a member of the great natural family of contagious fevers, of which small-pox may be taken to be the type.
2. That the living body of the infected man is the soil in which the specific poison, which is the cause of fever, breeds and multiplies.
8. That once cast off by the intestine this poison may communicate the fever to other persons in two principal ways„ either by contaminating the drinking water, or by infecting the air. . .
That by destroying the infective power of the intestinal discharges, by strong chemicals, or otherwise, the spread of fever may be entirely prevented. . . and that the disease may in time be finally extinguished.
(Typhoid Fever: Its Nature, Mode of Spreading, and Prevention, 1874)

Louis Pasteur
All these diseased ferments have a common origin. Their germs, infinitesimal and hardly perceptible as they are, even with the aid of a microscope, form a part of the dust conveyed through the air. This dust the air is continually taking from or depositing upon all objects in nature, so that the dust that clings to ingredients from which our beer is manufactured, may teem with the germs of diseased ferments.

. . .

In every case where the microscope reveals in a yeast. . . products which are foreign to the composition of alcoholic ferment. . . the flavor of the beer is more or less unsatisfactory, according to the abundance or nature of these minute organisms. . .
(Studies on Fermentation, 1879)

Joseph Lister (1827-1912)
[I offer] you my most hearty thanks for having demonstrated by your brilliant researches the truth of the theory of putrefactive germs, and for having afforded me in this manner the sole means of perfecting the antiseptic system.
Should you ever come to Edinburgh I am sure that you will be truly gratified to see in our hospital the extent to which the human race has profited by your work.
(letter to Pasteur, 1874)

Robert Koch (1843-1910)
Thus, for each disease a specific bacterium can be distinctly characterized by its physiological action, its conditions of growth, and its size and form. And, however often the disease is transmitted from one animal to another, the kind always remains the same and never changes into other kinds. For example, spherical bacteria never become rod-shaped bacilli.
(On Wound Infections, 1878)

If the number of victims is a measure of the significance of a disease, then all diseases. . . must rank far behind tuberculosis. Statistics show that one-seventh of all human beings die of tuberculosis, and that if one considers only the productive middle-age groups, tuberculosis carries away one-third and often more. Thus, . . . public health has sufficient reason to investigate this destructive disease.


"Koch's postulates"
1. The parasite occurs in every case of the disease.
2. The parasite does not occur in other diseases or nonpathogenically.
3. After being fully isolated and repeatedly grown in pure culture the parasite can induce the disease by being introduced into a healthy animal.
(Etiology of Tuberculosis, 1882)


Among practical results, one must also include the use of bacteriological methods to test water filtration. . . Similar techniques can be used to test milk and other foodstuffs as well as other articles that are suspected of spreading infection. The investigation of the air near watering canals and the consequential correction of widely held opinions that canal air is harmful, the investigation of air in class rooms, the identification of pathogenic bacteria in foodstuffs or soil all have practical consequences. . . I would also include the diagnosis of asiatic cholera and of the first stages of tuberculosis. . .

. . .

Allow me, therefore, to conclude this lecture with the wish that the strengths of all nations may be measured in this field of labor and in war against the smallest but the most dangerous enemies of the human race, and that in this struggle, for the good of all humanity, the success of each nation may repeatedly surpass that of the others.

(On Bacteriological Research, 1890)