Vibrio cholerae, better known as the silent killer
In 1854, a major epidemic struck London that would kill hundreds of residents in a short span of time. The disease was better known as cholera, and was not new to London since an outbreak had happened in 1831. Cholera, also known as Vibrio cholerae, is transmitted through water. Cholera can cause:
Diarrhea Early on will be fecal, but afterwards painless, massive "rice water stool" which contributes to large amounts of fluid loss ·
Vomiting Also contributes to mass amounts of fluid loss ·
Dehydration With diarrhea and vomiting combined these two movements lead to dehydration. Over 1/5 of a person's entire body weight can be lost in a single day. ·
Death If the body's water and electrolytes are not replenished rapidly within 12 hours, death may occur due to severe dehydration. Although cholera stunned many continents in the 1800's the immediate cause was unknown at the time. It was believed that cholera was transmitted through the air, but its cause was not known due to the lack of research done on the disease. Dr. John Snow would become known as the "Father of Modern Epidemiology for his hard work and research on the cholera epidemics that struck London in 1831 and 1854.
In 1831, John Snow was the age of eighteen and worked as an apprentice for Dr. Hardcastle when London experienced its first tasting of the cholera disease. Snow was sent to treat patients, who were mostly coal miners, but there was not much he could do to help them. The epidemic ended as soon as it started in 1832, and Snow continued to work on his M.D. degree for the next sixteen years. Theories explaining the cause of cholera
The "Miasma" theory was believed by many doctors to be the explanation of the spread of cholera and many other diseases in the nineteenth century. The theory stressed eradication of disease through the preventive approach of cleansing and scouring, rather than through the purer scientific approach of microbiology. Dr. William Farr was very supportive of this theory and reasoned that soil at low elevations, especially near the banks of the River Thames, contained much organic matter, which produces miasmata. The concentration of such deadly miasmata would be greater at lower elevations than in communities in the surrounding hills. Dr. Farr produced a graph to support his theory (as shown in Figure 1). Dr. Farr believed firmly in his theory until Dr. Snow's research was published, then his mind would be changed.
Figure 1 - The death rates for cholera seem to relate to the Miasma theory, but later on Dr. Farr's findings would be mere coincidence because the theory would be proved wrong later on.
The second theory was that of spontaneous generation of disease within the blood called the blood generation theory. This theory was essentially chemical, and as such, denied contagion. The most active supporter of the theory was the German chemist Justus von Liebig who held strong views on "fermentation" of the blood. The blood generation theory received negligible support in England.
The "Germ" Theory, which was supported by John Snow, theorized that cholera was caused by a germ cell. Snow did not know the exact germ cell that caused cholera, but believed that the germ was transmitted from person to person through contaminated drinking water. Many other peers, but especially Dr. John Simon (head medical officer of London), deemed Snow's theory peculiar.
Cholera Outbreak starting in 1848
Dr. Snow was thirty-five and another outbreak of cholera had surfaced in London. Snow had been waiting for another outbreak of cholera to happen, and would be tracking its every step. The first victim of the outbreak had been a merchant seaman who was stopping in London for a break and rented a room in the city. The seaman developed symptoms of cholera and died shortly thereafter. Snow's germ theory was supported when he learned that a second gentleman...
References: UCLA Department of Epidemiology, School of Public Health retrieved on March 10, 2006, from,
BIO 118: Cholera, retrieved on March 11, 2006 from,
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