Cholera is an intestinal disease caused by infection with the bacterium Vibrio cholerae. The infection is often asymptomatic, but can be quite severe. Approximately one in twenty infected patients exhibit profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and hypovolemic shock. Without treatment, death can occur quickly. 
Although cholera is rare throughout the developed world, it is endemic in Sub-Saharan Africa and other underdeveloped areas, and a common cause of mortality and morbidity.  Untreated cholera has a mortality rate of about 50 percent. Cholera came to the European continent in the 19th century as transportation started to develop. There were five large cholera-epidemics throughout Europe, which killed thousands of people. These epidemics sparked the sanitation reforms in large European cities during the 19th century, after John Snow traced a cholera outbreak in London to a single pump.
- In 1883 a German physician, Robert Koch, took the search for the cause of cholera a step further when he isolated the bacterium Vibrio cholerae, the “poison” Snow contended caused cholera. Dr. Koch determined that cholera is not contagious from person to person, but is spread only through unsanitary water or food supply sources, a major victory for Snow’s theory. The cholera epidemics in Europe and the United States in the 19th century ended after cities finally improved water supply sanitation.