Praying during a cholera epidemic. 19th-century illustration of people praying for deliverance from cholera. They are kneeling before a makeshift roadside altar under a tree. This is an area of Poland that was then under Austrian rule. Cholera, a bacterial infection of the intestines, was often fatal before modern treatments were developed. It spread in infected water supplies and killed millions in the 19th century. The bacterium causing the disease (Vibrio cholerae) was not identified until 1883. This engraving, by H. Woods, was published in the 1 November 1873 edtion of 'Harper's Weekly', published in New York, USA.