The acid sensitivity of V. cholerae means that a large dose is required to produced disease. Cholera is a disease of the small intestine, unlike most other enteric illnesses. The bacteria penetrate the mucus layer and adhere to the mucosal cells where they subsequently produce toxin. The potent enterotoxin choleragen is well defined. Binding via B leads to penetration of the A1 peptide, which enzymatically transfers ADP-ribose from NAD to a GTP regulatory protein.
Gastric acidity plays an important role in preventing cholera infection.
Also, genetic factors may be important since the toxin must bind to specific cellular receptors in order to function. Secretory antitoxin IgA may also play a role. Transmission of disease is primarily via water that has been contaminated by human feces. Carriage of vibrios is rare. Gastrointestinal symptoms and the presense of a rice water stool are presumptive for cholera.