Physiopathology of Cholera

The bacterium multiplies in the small intestine, where it adheres to the mucosal brush border. The bacterium is not invasive, in other words it does not penetrate the intestinal wall or pass into the blood. It excretes a very powerful toxin, which inhibits the absorption of fluid from the intestinal lumen and causes active fluid secretion towards the lumen. This fluid is isotonic, ion-rich and protein free. There are no intestinal ulcerations and the faeces do not contain blood. There is little if any fever. There is no tenesmus. The faeces contain significant amounts of sodium, potassium and bicarbonate. Because of this the intestinal content is slightly alkaline (V. cholerae thrives best in a slightly alkaline environment and is therefore producing the conditions which are optimal for its own survival). The loss of large amounts of alkaline faeces results in metabolic acidosis. People with blood group O have an equal risk of infection but are at a significantly higher risk of clinically severe cholera if they become infected. The reason is unknown.

Category: Medical Subject Notes , Microbiology Notes