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dehydrated.
    The bacterium makes a toxin (Cholera Toxin) that poisons the cells lining the gut. (By the way, to medical people, the gut is the hollow 10 m long tube that begins at the mouth and finishes at the anus.) These cells then exude—into the hollow pipe of the gut—huge quantities of a liquid rich in sodium, potassium and bicarbonate. The amount of liquid secreted is too much for the lower gut to re-absorb. The victim dehydrates rapidly thanks to their producing vast quantities of the infamous, so-called ‘rice water stools’. Someone with cholera can easily lose 0.5-1 litre/hr of fluid from their body.
    The bacterium makes a toxin (Cholera Toxin) that poisons the cells lining the gut. These cells then exude (into the hollow pipe of the gut) huge quantities of a liquid rich in sodium, potassium and bicarbonate. The amount of liquid secreted is too much for the lower gut to re-absorb. The victim dehydrates rapidly thanks to their producing vast quantities of the so-called ‘rice water stools’.
    Cholera Toxin
    (a simplified view)

Cell Membranes
The amount of water that crosses the cell membranes in the human body is simply astonishing.
Water molecules jump into the Red Blood Cells (RBCs) and then out again, and then in again, and so on. They do this very frequently. In fact, in just one second, a volume of water equal to about 100 times the volume of the RBC passes in and out of the RBC membrane. Obviously, these are mostly the same water molecules jumping in and out, over and over again. Assuming that you have about 2 litres of RBCs, this means that a total of about 17 million litres of water go in and out of your RBCs each day – that’s 17,000 tonnes of water!
This 17,000 tonnes of water is just for the 2 kg of RBCs. The tonnage of water must be correspondingly higher for the remaining kilograms of your body.
With such a huge flow, you need only a slight interference with the flow in one direction to rapidly over-hydrate or dehydrate you.
As a personal example, I knew one woman who suffered from pre-eclampsia (nothing to do with diarrhoea, but lots to do with keeping too much water in the tissues). The ‘cure’ for pre-eclampsia is immediate delivery of the baby. After delivering her lovely baby (in a bit of a hurry), she then urinated away 10 litres of water that same day, and another 10 litres over the next two days.
    Incredibly, in some cases, the patient can actually die of dehydration before they have their first episode of diarrhoea—this is called Cholera Sicca. In these victims, the poisoned cells that line the gut dump litres of fluid into the hollow pipe that is the gut. This fluid cannot be re-absorbed into the bloodstream. In Cholera Sicca, this happens so quickly that the victims do not have time for a bowel motion. In fact, they die before they even go to the toilet. When a cholera pandemic hit Paris in 1831, it killed so many people so quickly that François Magendie, the French physiologist, wrote that it was ‘a disease that begins where other diseases end, with death’.
    Typically, the death rate for cholera is about 50% if untreated, and 1% if treated. In India alone, between 1816 and 1917, nearly 30 million human beings died from cholera. Most deaths from cholera occur on the first day of infection.
    The disease will resolve itself in a few days, when healthy gut cells replace the poisoned ones. However, in the 50% of cases of untreated cholera that lead to death, the victim dies from dehydration before the poisoned cells can be replaced.
    Cholera—Treatment
    You would think that the treatment for massive diarrhoea from cholera would be easy—simply replace the water at one end as fast as it is being lost from the other end. But it doesn’t work like that. The problem is that the water you drink does not get absorbed by the gut.
    Giving water to cholera victims only increases the loss of water as rice water stools. The ‘replacement’ water does not leave the gut to enter the