Richard Smith: What causes cholera? A Victorian debate

richard_smith_2014Yesterday I was in The Cholera Hospital in Dhaka, Bangladesh; today I’m reading about a highly emotional debate about the causes and treatment of cholera that took place in India in the 1857, during the Indian Mutiny. Both experiences have taught me something, and you might learn something as well.

Cholera today

Cholera is endemic in Bangladesh, as it is in some 50 countries, with two peaks during the year, one just before the rainy season begins in April and one after it ends in October. During the peaks The Cholera Hospital may have a thousand admissions a day, most of the patients have cholera. The hospital is part of icddr,b [formerly the International Centre for Diarrhoeal Disease Research, Bangladesh], and it leads the world in the treatment of cholera. If patients arrive alive they leave alive. Nobody has to pay for treatment, and the hospital is well known to the poor of Dhaka, a city of 17 million people where a third live in slums.

Teams from the hospital travel the world leading the response to cholera outbreaks. And icddr,b both developed oral rehydration treatment and conducts many trials of cholera vaccines. None of the vaccines are very effective in Bangladesh, probably because the guts of Bangladeshis are laden with bacteria. Clean water and sanitation are lacking because of the slums and because Dhaka might be described as a city built on water.

During the two peaks a large tent is erected in the car park and filled with cholera cots, narrow beds with a hole in the middle. They are inches apart in the gloom of the tent, and the first image that springs to the mind of a British visitor is Florence Nightingale at work in the Crimea. It’s a doubly appropriate image in that the hospital has high standards of cleanliness and infection control and in that the hospital is largely nurse run.

The Victorian debate

The Victorian debate over the causes and treatment of cholera is described in The Siege of Krishnapur by J G Farrell, a novel that won the Booker Prize in 1973 . I’m rereading the novel because I’ve just learnt that one of the doctors, Dr McNab, is based on my friend Robin Stott, the chair of the Climate and Health Council. McNab is unlike Robin in that he’s grave and humourless, but like Robin in paying a lot of attention to the evidence, careful in observation (to the point of meticulously recording every stage of his wife’s death from cholera), and willing to challenge conventional thinking.

McNab’s rival in the debate is Dr Dunstaple, an old fashioned doctor who enjoys the status of being a doctor and is more interested in pig sticking than medicine. Dunstaple is an emotional man and is driven close to madness in his hatred of and distain for his rival, causing much distress to his daughter and wife.

It’s alarming for the lice ridden, near skeletons left in Krishnapur that the two doctors have theories and treatments that are diametrically opposed. Whom should they ask to treat them if they develop cholera? How can they decide? Some think that the older, avuncular Dunstaple must be the best; others worry he may be out of date. Dunstaple is cheery and confident; McNab can be gloomy. Dunstaple has more adherents. People have cards in their pockets stating whom they want to treat them; sometimes they’ve scratched out one name and inserted the other, sometimes several times. Farrell is setting up a controlled trial.

Eventually Dunstaple can stand it no more and interrupts a religious service to condemn McNab as a charlatan. He challenges him to a debate and begins by stating that doctors should follow established treatments not perform “hare-brained experiments.” McNab, he says, holds the “discredited belief that you catch cholera by drinking,” “by taking morbific matter…into the alimentary canal,” and that it is spread by “rice-water” discharges becoming mingled with the drinking water of others.” McNab says that Dunstaple has described well what he believes.

But, continues Dunstaple triumphantly, the Royal College of Physicians states that the cause is “matter increasing by some process, whether chemical or organic, in impure or damp air.” His audience is impressed. Then he becomes more scientific, producing evidence from an outbreak in Newcastle and talking of “ganglionic nerves” and blood being “carbonated.” His audience is even more impressed.

Then Dunstaple turns to treatment, which is based on restoring animal heat: a warm bath, blisters to the spine, mustard plasters to the pit of the stomach, brandy, and pills composed of calomel, opium, and capsicum.

Now it’s McNab’s turn. He takes a long time to begin, worrying the few supporters he has left. He begins with uncertainty: there is no accepted treatment for cholera, “the medical journals still present a variety of possible methods, many of which sound most desperate and bizarre.” Now he makes a rhetorical mistake, illustrating bizarre methods by referring to Chinese missionaries who have seen people treated by needles being stuck into their bellies and arms. This graphic image stays with some of his audience, who think he is advocating it.

Continuing, McNab comes close to describing the germ theory, which hadn’t yet appeared, and says that the basic problem is dehydration caused by massive loss of fluid. So the basis of his treatment is “simply to restore the fluid and salts which have been lost from the blood, by injecting solutions of carbonate of soda…into the blood vessels.” McNab’s delivery is conversational and monotonous, and the audience hardly follow him. Dunstaple is oratorical and swings back into the debate with evidence of what is seen in the heart at post mortem, but McNab responds that the signs are compatible with his theory.

The debate is now interrupted, and the feeling is that Dunstaple is winning. Doctors reading the book will know that McNab is right and will be wondering which of their present treatments are as ineffective and harmful as those of Dunstaple for treating cholera. I thought of depression and its treatments. But it seems to me that the debate would be no less enjoyable to those who know nothing about cholera.

The result

Dunstaple grows ever more furious and later asks McNab to provide evidence to support his theory, throwing in that a dispenser who accidentally swallowed some of the “so called ‘rice water'” and had not developed cholera. McNab can’t explain that (we now know that you need a large dose of the cholera bacteria to develop cholera, accounting for medical staff usually not catching it while caring for patients with cholera), and illustrates that there is much that is not known, including why Jews might be immune. This was another rhetorical mistake, mentioning Jews in an age when anti-semitism was normal.

McNab then launches into a description of the famous and at that time recent John Snow study comparing cholera rates among customers who got their water from the Lambeth Company and those who got it from the Southwark and Vauxhall Company. He quotes convincing statistics, but his audience was far from impressed, suffering “cerebral indigestion” from the flow of figures. Inevitably I thought of experts and politicians hurling statistics at each other on television and in the newspapers today and having exactly the same effect.

But Dunstaple knows better how to convince his audience: he produces a bottle of “rice water” and drinks it. “Against this argument Dr McNab’s tiresome statistics could not hope to compete.”

Farrell is capturing the drama that occurred in Munich in 1892 when Max Joseph Pettenkofer did the same to disprove the germ theory. I’ve stood in the lecture theatre where it happened. Pettenkoffer did not become infected, but he later killed himself when his theory was discredited. Informed readers might also think of the Nobel prize winner Barry Marshall in 1984 drinking a suspension to show the bacterial cause of peptic ulcers.

So what we have in the book is not a controlled trial but a more dramatic “N of 1” trial. Dunstaple develops cholera and is treated with his methods, including a warm bath. The false logic of the warm bath is that it warms the cold skin, but in fact it worsens the circulatory collapse by drawing more blood to the skin. Dunstaple sinks into a coma. His daughter calls McNab who revives him with injections. Dunstaple is furious and reinstates his methods. This happens several times until Dunstaple dies “inconclusively, of a heart attack.”

Those who are left know the detail of what has happened but are unconvinced that McNab is right: Dunstaple’s treatment might not have had time to take effect. Hadn’t McNab used that Chinese treatment with needles, and wasn’t he a Jew. “I never knew such stupidity could exist,” the leader of the group says to himself.

I can but admire Dunstaple for being so convinced of his beliefs that he’s willing to die for them, and I think of many modern controversies—for example, around diet and whether the MMR vaccine causes autism. We often repeat McNab’s mistake of hoping that reason and statistics will defeat emotion, human stories, and drama.

Science did help us understand cholera, but The Cholera Hospital in Dhaka still has hundreds of thousands of admissions a year, the world has 3-5 million, and we don’t have a vaccine that is as effective as we need.

Richard Smith was the editor of The BMJ until 2004. He is now chair of the board of trustees of icddr,b [formerly International Centre for Diarrhoeal Disease Research, Bangladesh], and chair of the board of Patients Know Best. He is also a trustee of C3 Collaborating for Health.

Completing interest: RS is the chair of the board of trustees of icddr,b.