Introduction to Theory-Based Research and the Scientific Method

John snow (1813-1858) was a british physician who specialises in anesthesia and medical hygiene. He was considered as the founder of modern epidemiology because of his works and contributions to the identification of aetiology of the cholera outbreak in the year 1854 in England. In 1855 when John Snow published his works on “The Mode of communicaton of cholera,” he was not really regarded as an authority when it comes to epidemiology.  His theory was based on the analogical reasoning of the pathology and therapeutics of the disease (Eyler, 2001).  He was skeptic about the former epidemiological theory such as the miasma theory and the germ theory. During the time of this discovery, he did not accept the view that cholera and some other view that diseases were actually caused by pollution or some other noxious substance.

The works of Snow on the epidemiological studies of cholera was as follows, he started by considering the enviroment affected by the epidemics and simultaneously considering the pathology of the disease. He explained that the first symptoms of the cholera is the abdominal symptoms suggesting the causative factor of such kind of disease is likely to be a morbid material or poison which act locally by irritating the surfaces of the stomach and the intestines. This later leads to symptoms such as pain, vomiting , diarrhoea and dehydration the major symptoms of the cholera(Eyler, 2001). He later concluded that since the early stages of cholera do responds to treatment with substance like opium or chalk which also ack locally, then this attribute of the drugs suggested the cholera as a local disease. He continued in his first publication by pointing towards the route of infection of the cholera in that he suggested the disease to be a disease that must have been ingested because its a local disease of the gut( Eyler, 2001). When he later published his second edition of the mode of communication of cholera, he then significantly elaborate he’s discoveries on the epidemiology of the disease. He believed that there must be a large amount of the material causing the disease in the intestinal discharge of the cholera patients and that the disease must be a communicable one which is propably transmitted when there is ingestion of food substances or water that has been contaminated by the intestinal discharge of the other victims (Eyler, 2001).

After different visitation to the site of outbreak and different conducted studies, he then suggested that most people affected were those closer to the pump, where most individual that were affected get their water supply from. He did this by maping out the affected areas, to be around the pump. And with various statistics and findings he was able to conclude that most victim of cholera are being supplied by the sewage polluted sections of Thames water, hence increase in incidence of the disease. From the identification of the abdominal symptoms to the association of the ingested materials causing a local irritation and diseased states to the identification of the feco-oral route as the route of infection, it can be stated clearly that Snow’s work is based on scientific model or approach to identifying the causal factors and epidemiology of a particular diseased state.

William Farr is regarded as the father of epidemiological statistics and was even given more regards during the time of the cholera outbreak in England. He was the Statistical Superintended of the General Register Office and a member of the Commitee on Scientific inquiries in 1854 (Eyler, 2001). He contributed a lot on the epidemiology of cholera. He discover that most of the death recorded as a result of the cholera epidemics actually occured in some specific region and countries. He also analyse the local influences on the the cholera fields he examined, for instance he stated that there is an inverse relationship between the cholera field of London and the soil elevation and later made some calculations and conclusion where he considered human mortality has been a predictable, regular and capable of mathematical decriptive terms (Eyler, 2001). He’s studies and report were consider as having the greatest explaination when it comes to cholera epidemics and he’s works were also suggested to have gave John Snow a fore-knowlegde or basis in which his researches were conducted upon.

Farr also believe the agent causing the cholera are organic and non living and also try to explain the action of such agents as putrefactive action by using the writings of the the German organic chemist Justis (Eyler, 2001). He also try to establish a similarity between the disease process and the chemical processes involve by using the word zymotic to describe epidemic, endemic and contagious disease (eyler,2001). He believed in the Miasmatic theory of explanation where he believed that cholera was actually spread via inhalation of the agent with the lungs. He believed the materials were quite abundant in the atmosphere where the victims contacted it. He’s major purpose of the experiments and the research work is to show the prevalences of endemic, epidemics and contagious of the diseases depend on the some enviromental factors.

Though Farr was not really convince by the outcome or conclusion of the Snow’s work but he still regarded the works of John Snow as the most important of all cholera research papers or works he reviewed during the outbreak. He recognize the fact that polluted river water could be plausible but believed that most river towns that are located on the lower terrain tend to have more prevalences of the disease than those on the higher terrain because the lower one tend to inherit the agent from the higher ones.

The effect of Farr activities had a profound effect on Snow’s epidemiological investigations in that, it created the background for snow to work on. This can be identified when we consider the studies on the water supply companies and the consumer of their product. Snow also obtained the adresses of the victims from the Farrs office and later carried out his own investigation in the following year. Hence, considering Snow and Farr as a scientific duet is the best term to show their great contributions to epidemiology.

References

Eyler, J(2001). The Changing Assessments of John Snow?s and William Farr?s Cholera Studies. Soz Praventiv Med 2001:46 (4): 225-232

Retrieved Nov 28, 2008 from http://www.epidemiology.ch/history/papers/eyler-paper-1.pdf.

Morabia A(2001). Snow and Farr: A Scientific Duet. Soz Praventiv Med 2001:46 (4): 223-224

Retrieved Nov 28, 2008 from www.epidemiology.ch/history/papers/SPM%2046(4)%20223-4%20Morabia%20Editorial-2.pdf.