Cholera is an infectious disease of the small intestines that is caused by the bacterium Vibrio cholerae. This disease is a waterborne and foodborne illness, where water and food is contaminated by feces of an infected individual. The symptoms of cholera include: watery diarrhea and vomiting. These symptoms cause dehydration and an imbalance in electrolytes for the infected individual. Primary treatment for the disease is rehydration therapy. Severe case of the disease can lead to hospitalization and even death.
The cholera disease is monitored because of the potentially dangerous effects of cholera to populations and its ability to be spread easily. The World Health Organization (WHO) collects data for diseases such as cholera. This data can be used to analyze the trends in cholera occurrences throughout space and time, and this exact analysis was done!
Methodology
Data provided by the WHO for the continent of Asia was downloaded. This data contained the number of cholera occurrences, cholera deaths, and the death rate for each country form 1950-2011. This data is provided as tabular form. To analyze geographic trends, the before mentioned data was combined by year to provide total occurrences, total deaths, and average death rate for each country and then joined with county shapefiles. The time analyses combined the cholera data for total occurrences, total deaths, and average death rate for the entire continent to display the trends through time.
Results
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Conclusions
Cholera still affects populations in developing countries or countries that have poor sanitation practices. Logically thinking, cholera was a big problem in the past. That is clearly seen in the graph where the trend has a negative slope approaching current times. Geographically, India is shown to be consistent in high total occurrences, total deaths, and death rate. This could potentially be because India is over populated and lacks proper sanitation in some portions of the county.
The data provided by the WHO is all reported data from individual countries. There could possibly be missing data and the whole picture for cholera in Asia is not displayed correctly. Regardless, the fight against cholera is shown to be improving and that is a good outlook.
Side Note
Cholera and GIS have a little history together...one the first GIS studies completed was done by an English physician named John Snow in 1854. There was a large cholera outbreak in London and he sought to figure out why (cholera back then was thought to be spread by "bad" air). He created a dot map of cholera cases around a water pump to illustrate the clustering of cases. He also used statistics to link cholera infection to water quality. John Snow's cholera map can be found here.
