Cholera is caused by a comma-shaped bacterium, vibrio cholerae , which is ingested in contaminated water and food. The bacteria multiply enormously in the intestine, where epithelial cells allow fluid to leak into the intestine with intense diarrhoea as a result.
Cholera is endemic in India and other parts of the third world.
The bacterium discovered by Robert Koch in 1884, can be killed by antibiotics, but the disease is caused by a bacterial toxin, which irreversibly activates the G proteins of epithelial cells in the intestine. This results in an often life-threatening loss of water and salts. The toxin acts as an enzyme that changes the G protein so that it can no longer switch itself off. The activated G protein changes the function of epithelial cells in the intestine, with enormous loss of water as a result. These pages are based on material from the 1994 Physiology or Medicine Nobel Poster.