The causative organism is a Spirillaceae bacterium. Cholera was originally confined to India early in the nineteenth century. Humans are the only known host for the cholera vibrio . The disease must be maintained by an unbroken chain of mild or subclinical infections. The true home on endemic cholera is the Yangtze River Valley in China and the delta of the Ganges in India.
Cholera remains endemic in Asia, the Middle East, Africa.
It is spread by water, seafood, and other foodstuffs contaminated with the excrement of infected persons. The composer Tchaikovsky is said to have died of it in 1893 after drinking unboiled tap water in Russia. Epidemics of cholera and other water borne diseases in Chicago led to the engineered reversal of the Chicago River at the turn of the century with the opening of the Sanitary and Ship Canal. This ended forever contamination of Lake Michigan drinking water by Chicago sewage which heretofore had been emptied into the lake. Earlier, in 1885, six inches of rain in less than a day caused such contamination of the Lake Michigan water supply that deadly outbreaks of typhoid fever, cholera, dysentery and other water borne diseases devastated the city.