Introduction
The topic of epidemics is a common feature in today’s global issues that is affecting humanity in almost every part of the world. Cholera is an epidemic that has troubled man for a long time and efforts in finding ways of curbing the epidemic to prevent further devastating effects has been underway in different parts of the world. In the mid nineteenth century, the eruption of cholera in London prompted many researchers to embark on a mission to find the actual causes of cholera which was proving to be one of the major health concerns and probably one contributor to increasing mortality rate. Two theories were suggested to explain the causes of cholera. John Snow in 1848-49 gave the initial theory that suggested that cholera is caused by micro-organisms that are communicated from one person to another through contaminated water or food. The other theory was suggested by William Farr where he indicated cholera is caused by organic materials that are airborne and enters the body through the lungs. The papers done by John Eyler and Alfredo Morabia and UCLA gives a clear indication about how the theory by Snow was initially ignored at first but became recognized only later as a reference of modern epidemiology and how Snow findings helping in prevention and treatment of cholera.
Eyler, JM. The Changing Assessments of John Snow‘s and William Farr’s Cholera Studies. Soz Praventiv Med 2001:46 (4): 225
The objective of the study by Eyler was to show how the studies by Snow and Farr brought about conflicting conclusions merely because of the methodology used in arriving at the conclusions. Although epidemiology which relies much on observations was the method used by Snow, it could not be accepted readily as a reliable method to draw conclusions. (Dallal 2000: Para 8) Later, it was effectively applied to arrive at conclusion on the cause of cholera and proved its reliability over other scientific methods like that applied by Farr. In his findings, Snow found out that cholera which is communicable is spread when human consume food or water that is contaminated with the intestinal discharge from other victims of cholera. In addition, Snow compared the mortality rates in a sample of large population which consumed water with varying degrees of sewerage contamination. It was revealed that among the population that consumed water from companies that supply water to the people without carrying out water treatment or filtering process, mortality rate due to cholera was observed to be high.
On the other hand, unlike Snow’s theory, William Farr held a different theory by suggesting that cholera enters the body though the lungs. In supporting his theory, Farr suggested that air is contaminated with organic materials from respiration, perspiration, decomposition, or putrefaction. Further, unlike Snow who suggested that the cause of cholera is due to prior existence of the disease, Farr indicated that air is contaminated with the organic materials that cause cholera produced by zymotic material by chemical means and not necessarily because of prior existence of such disease. Farr tried to study cholera by investigating the roles of sex, age, season, day of week and soil elevation. He was able to predict using mathematical terms the mortality of humans due to cholera. The zymotic theory of Farr suggested that cholera is most prevalent in low moist soil areas due to the fact that those conditions favor the decay and putrefaction of organic materials. In addition, as the land elevation increases, the concentration of the airborne organic materials decreases regularly. The findings of Farr agreed with the study carried in certain places to suggest that it was viable to explain the causes of cholera. Unlike Snow, Farr only viewed sewage contamination in water merely as one cause of miasmata that produces the organic materials and that it is trough evaporation that materials get to air and enter the body through lungs. In his study, Farr was out to suggest that the prevention of cholera would only be realized by carrying out sanitary reforms in the environments.
Eyler concludes by acknowledging that, although Farr worked hard to convince that his zymotic theory was right as far as causes of cholera is concerned, Snow’s theory is largely accepted and the conclusion is that cholera is caused by consumption of sewerage contaminated water and not airborne organic matter as Farr had suggested.
Morabia A. Snow and Farr: A Scientific Duet. Soz Praventiv Med 2001:46 (4): 223-224.
The objective of the study by Morabia was to show the different approaches that were taken in the study of cholera and how the synergies were brought together by Snow and Farr in finding the most appropriate and true explanation on the cause of cholera. It can be shown in the article that although the theory brought forward by Farr was later abandoned, his activities on drawing the conclusions laid a good ground on what is commonly known as surveillance of disease.
The study on the arrangements of water supply in London gave Snow the basis on which he anchored his arguments by hypothesizing that if cholera was caused by consumption of contaminated water, then, the mortality rates would have been higher among the population that drank contaminated water from Southwark and Vauxhall companies and lower among people who consumed cleaner water from Lambeth company. It is evident that the mode of transmission of cholera was a synergy that drove both Snow and Farr. The author acknowledges that Snow had the right hypothesis while Farr demonstrated the advanced public health surveillance system that easy convinced the public.
In conclusion, it is indicated that the work by Snow and Farr was important as far as cholera as an epidemic is concerned. Snow’s contribution enabled the discovery of the right cause and the mode of transmission of cholera while the work by Farr contributed to demonstrating good public health surveillance not only regarding cholera but also other diseases and epidemics. Therefore, though they did not work together as such, Snow and Farr are viewed as “scientific duet” whose contributions are vital.
UCLA Department of Epidemiology School of Public Health (2001) Broad Street Pump Outbreak
The article by UCLA gives the events in nineteenth century in England when cholera outbreak was a major health problem first due to the fact that its causes and modes of transmission were not known. The hypothesis was that cholera was spread by miasma in the atmosphere had been adopted although it was later changed by the discoveries of John Snow who through epidemiology found out that cholera is spread by contaminated water.
The article indicated that through observation which forms a key part of epidemiology, interviewing people and testing of water samples, Snow was convinced that the cause cholera was through consumption of contaminated water.
The paper concludes by indicating until now the explanation on the causes of cholera as given by Snow still hold by the fact that the methods of prevention of cholera of preventing water contamination by sewage or clearing of cesspools.
Conclusion
All the findings in the articles indicate that although the findings by Snow on the causes of cholera had not been embraced for a long time, he was later upheld for his work which discovered the causes of cholera as contaminated food or water. In addition Snow has highly regarded as one of the founders of epidemiology as a tool to be used in studies relating to epidemics and diseases. Although Farr’s elevation theory was generally accepted due to his survey methodology it was later found inappropriate and untrue as far as cholera spread and prevention is concerned.
The study by Snow can be regarded to rely on causality in that in his epidemiology study he relied on observation without undertaking tests on a predetermined group of people in order to compare the results as is usual with statistical study.
References
Dallal, J. (2000). Cause and Effect. Web.
Eyler J. m. (2001) History of Epidemiology: the changing assessments of John Snow’s and William Farr’s cholera studies, NY: Soz Praventivmed
Morabia A (2001) Snow and Farr: a scientific duet. NY: Soz Praventivmed UCLA Department of Epidemiology School of Public Health (2001). Broad Street Pump Outbreak. Web.
Wudka, J. (1998). The Scientific Method. Web.