Question

Write about "London Cholera outbreak" by following the guidelines bellow step by step:

1. Formulate a hypothesis

• Based on a data review, what caused the outbreak?

1. Confirm the hypothesis

• Identify additional cases; conduct laboratory assays to verify causal agent.

1. Draw conclusions and formulate practical applications

• What can be done to prevent similar outbreaks in the future?

Answer 1

Answers :

"London Cholera outbreak"

Introduction

In 1854, a cholera outbreak swept over the Soho district in London. The outbreak reached its peak on the first week with more than 150 deaths, causing wide spread panic in the neighborhood which lead to the flight of its residents. At that time, the cause of cholera was not scientifically established, and people believed that toxic vapors resulting from the decay of organic matters was the cause of cholera, among other diseases. Dr. John Snow (1813 - 1858) was skeptical of this theory. To investigate other causes, Snow made his famous map of the Soho district, plotting the location of deaths alongside street water pumps in the neighborhood. At that time, the data acquisition and visualization tools at Snow's disposal were severely limited by todays standards. Nevertheless, Snow's visualization was arguably the first clear evidence that linked cholera transmission to contaminated water supply.

Cause of the cholera outbreak:

Dr. Snow believed sewage dumped into the river or into cesspools near town wells could contaminate the water supply, leading to a rapid spread of disease. In August of 1854 Soho, a suburb of London, was hit hard by a terrible outbreak of cholera.

Dr John Snow Theory and Methodology :

The methods of Dr Snow’s used in the 1849 cholera outbreak in London was a superlative example and used in modern of Epidemiology (Peter Vinten-Johansen, 2003) (Frerichs, 2009 ). Dr John Snow was able to build a successful theory based upon statistics and geographical tools, not usual used on that time and which enabled public health organization to combat the disease (Harning, 2015).

He used the map by pointed the incidence of the disease, he found that over 500 cases occurred within 10 days over an area of some 250 yards on London’s Broad Street. He investigated for some poison can come from the excreta of cholera patients, the main factors were the water from the Broad street pump and the local people used this source of water.

Dr Snow until he died in 1858 not found what caused cholera. In 1876 the German doctor, Robert Koch discovered cholera causes by bacteria called Vibrio cholera (University, 2004)

In 1854, the British Parliament applied Snow’s theory of water contamination to successfully diminish the impact of the disease and how to control the spread. this theory and the methodology used by Dr Snow can say is a start point for many applications in all sciences and produce the revolutionary in health and public policy in the UK and whole the world. (Harning, 2015).

Snow hypothesis is water contamination is main resource, according to that he start test water source Figure 1, there two water companies had drawn upon water from the River Thames that had been contaminated by sewage. He check houses and interviewed people about their source of drinking water to find the cholera mortality to the source of water and he found more mortality between those drinking the water supplied by the water companies, and he use these data in his research process, he turned his attention to the five pumps near Golden Square, which most of them contained contaminants that were visible to the human eye.

Snow concluded that the disease transmission over longer distances was caused by drinking water contaminated with raw sewage containing the specific cholera poison. In 1849, Snow described two local cholera outbreaks in southern London that seemed to strongly suggest a water – borne route.

Snow’s methodology based on collecting geographic and epidemiologic data with clinical, pathological, and chemical data , by collecting this information helps him to demonstrate the severity of the outbreak and find the main resource cause the disease and how to spread very fast. Figure 2, the white section of the map shows the area of particular interest to John Snow. The blue area is encompassing the Broad Street Pump is circled.

Five Basic Cholera Prevention Steps for similar outbreaks in the future?

1. Make sure to drink and use safe water to brush your teeth, wash and prepare food, and make ice.
2. Wash your hands often with soap and safe water.
3. Use latrines or bury your poop; do not poop in any body of water.
4. Cook food well (especially seafood), keep it covered, and eat it hot.
5. Clean up safely in the kitchen and in places where the family bathes and washes clothes.

Conclusions
According to the World Health Organization, 78% of the people in Third World countries are still without clean water supplies until today, and around 85% of those people don’t live in areas that have sewage treatment, making cholera disease spread easily .

Today, scientists think that Snow is the pioneer of public health analysis in an excessively medical field. Snow’s research used the epidemiologists ‘ approach today. To formulate a hypothesis, he used his clinical knowledge and observations on the distribution of cholera rates

The idea of using map and collect data by Dr Snow turn today in desktop mapping revolution using in public health investigators, such as Geographic information systems (GIS) to show the geographical distribution of individual or aggregate morbidity or mortality, and can use in scientific fields.

The GIS and remote sensing techniques used for early detection and response to infectious disease more easily and faster than other technique, The incorporation of traditional epidemiological statistical techniques into a GIS interface enables researchers to gain a better understanding of the spatial aspect of disease spread.

References

• Barton, n.d. www.pastmedicalhistory.co.uk. [Online]
  Available at: https://www.pastmedicalhistory.co.uk/john-snow-and-the-1854-cholera-outbreak
  [Accessed 14 02 2019].