Tuesday

ben goldacre on cholera

ever wanted to know how cholera works?

In fact, the story that science can tell about cholera is well characterised and fiendishly fascinating. If you swallow some cholera bacteria, they shut down to pass through your murderously acidic stomach, and then, when they detect (from the changed chemical environment) that they are in your small intestine, they start producing curly whip-like tails. These rotate to propel the bacteria through the pasty mucus that lines your small intestine, and up against the intestinal wall, where they can thrive.

Once here, they again respond to their changed chemical surroundings, and stop producing the tails, and instead, start producing cholera toxin. This toxin pulls chloride ions across the bowel wall, and so water is drawn across with them, by osmosis, from your blood supply and into the passageway of your small intestine.

This happens on a massive scale: your small intestine is suddenly full of water, which flies out of your arse at a phenomenal rate, carrying the multiplying and thriving new generations of Vibrio cholerae bacteria out into the drinking water and so on to the next host, chillingly, perhaps your brother, perhaps your girlfriend – unless proper sanitation measures are in place.

Meanwhile, as this water flies out of you, dehydration rapidly begins to set in, and the only thing you can do to save your life is make sure you consume – almost continuously – the right mixture of dilute salt water and sugar, to replace the blood’s water and salts lost in the diarrhoea.

And fascinatingly, the single most successful evidence-based medical treatment in the history of humankind is something you’ve probably never heard of: the WHO rehydration recipe, used to treat people with diarrhoea, which has saved 3 million lives a year for the past two decades. In fact, diarrhoea kills more young children around the world than malaria, AIDS and TB combined.


from his post ostensibly about teaching hocum in universities.
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