Cholera is a water-borne, diarrhoeal disease caused by the bacterium Vibrio cholerae. For illness to occur, humans must consume vast amounts of the bacteria and cholera must possess a cluster of genes involved in creating the toxin co-regulated pilus. The gene for cholera enterotoxin must also be expressed. Treatment for cholera involves giving victims oral rehydration and antibiotics as a secondary defence. ‘Cholera’ explains that cholera gave rise to the foundation of epidemiology and Koch’s postulates, which state the requirements for identifying a particular organism as the causative agent of a disease. It also describes the ways in which cholera evolves antibiotic resistance, the interactions between Vibrio cholerae and the viruses that prey upon it, and possible reasons for the seasonality of epidemics.