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How does cholera toxin cause severe fluid loss?

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Diagram of a water treatment plant showing the process from water inlet through mixing, coagulation, flocculation, settling, filtering, chemical treatment with chlorine, storage, and high-lift pumping to the distribution system. — water purification Water from inlets located in the water supply, such as a lake, is sent to be mixed, coagulated, and flocculated and is then sent to the waterworks for purification by filtering and chemical treatment. After being treated, the water is pumped into water mains for storage or distribution.

Cholera toxin causes severe fluid loss by disrupting the normal function of intestinal cells. Once the Vibrio cholerae bacterium infects the intestine, it secretes an enterotoxin that binds to receptors on the lining of the small intestine.1

A portion of this toxin enters the intestinal cells and increases the activity of an enzyme responsible for regulating a cellular pumping mechanism. This pump controls the movement of water and electrolytes between the intestine and the circulatory system. Under the influence of the toxin, the pump becomes locked in the "on" position, forcing the outflow of enormous quantities of fluid—up to one liter per hour—into the intestinal tract. This extreme loss of water and salts is the direct cause of the clinical manifestations of cholera, including profuse watery diarrhea and rapid dehydration.123