Saturday, March 26, 2016

The Pump Handle

Cholera is one of those diseases that the major industrialized Western countries no longer remember:  it is a malady of the third world or a long-forgotten past. 

The United States still has a few dozen reported cases every year, but no one has died from it in years.  We no longer remember the years in which over a hundred thousand succumbed annually, or that it was the disease that killed former President Polk.  Outbreaks in third world countries rarely make the news, since this is a problem no longer relevant to us.

Cholera is an infection of the intestines by the bacterium Vibrio cholerae.  While the incubation period can be anywhere from just a few hours to several days after exposure, and the symptoms may vary greatly, in the most severe cases the victims die of dehydration after experiencing days of vomiting and copious watery diarrhea.

The disease is actually a hazard of urbanization and overcrowding.  Its spread is a result of the rapid rise of urban populations and the associated concentration of human waste.  And, of course, the eradication of cholera in the cities turned out to be a by-product of the solution to the urban human waste problem.  Having solved that waste problem, of course, we have forgotten exactly what happened.

In the middle of the nineteenth century, London was already a city of over two million people, who were crammed into a impossibly small amount of real estate—the most populous city on earth.  And it stunk...Literally stunk.  With no centralized sewage system, every building in the town had its own cesspool, all of which overflowed with human waste and were sporadically emptied—by buckets—into waste carts that simply dumped their contents into the Thames River.  The Thames, of course, was also the source of drinking water for London—so convenient!.

None of this particularly worried the health officials, who knew that disease was spread by "bad air"—the miasma theory.  Every educated person for millennia had known that harmful vapors that  were the result of rotting organic matter spread diseases like the plague, cholera, and chlamydia.  (By the days of Victorian England, some physicians were blaming obesity on the effect of inhaling the odor of food!)

In 1849, there was yet another outbreak of cholera in London, which began with the death of only twelve people.  A physician, John Snow, noticed something interesting about the outbreak.  The first case was a seaman who had just come from Asia.  A week later, the second case was a man who lived in the same room at the same boarding house cottage.  In total, all the victims lived in a row of cottages that shared a single well.  Snow reasoned it was highly unlikely that the "bad air" had hung around in the same room and the same buildings for a week. 

On examination, he discovered that a drainage channel for waste water ran in front of the house.  Despite the fact that the rock-lined channel had visible cracks that allowed the waste water to seep into the well, the cottage tenants continued to use the channel for an open cesspool.  While Snow had absolutely no idea how the disease spread (this was more than a decade before Pasteur would postulate his germ theory) Snow reasoned that the disease was spread by the contaminated water.

He published a paper on the subject—a paper that was almost completely ignored.  The city's health officials absolutely believed in the miasma theory of disease.  ('Hell, you could smell the filth in the air...')  Not surprisingly, the cholera outbreak spread, eventually killing 14,137 people in 1849.

In 1854, London suffered another outbreak in Soho.  While today this is a delightful area of town, noted for its galleries, trendy nightclubs, pubs, and small expensive boutiques, in 1854, it was a slum so packed with people that each room in the buildings housed an average of four people.  Centuries-old overflowing cesspools lay just a few feet away from public water pumps. 

The first case of cholera in this outbreak was a six month-old infant.  In the next three days, another 127 people died.  This triggered a panic and residents of London began fleeing the city in numbers not seen since the Great Plague of 1666.  Within a week, three-quarters of Soho had fled.  The Soho outbreak was far worse than average:  the area around Broad Street was quite literally decimated—one-tenth of the population died.

Snow lived in Soho, and he began interviewing the victims' families.  He also began marking a map with the location of the victims' homes and it did not take long for a distinctive pattern to emerge.  Almost all of the victims lived near a specific public water pump on Broad Street.  The infant who had succumbed first lived in a house with an overflowing cesspool located  just three feet from the well.

Unexpectedly, several of the victims lived closer to public pumps other than the one on Broad Street and there were no cholera cases among the workers at a large brewery adjacent to the pump.

Snow continued his interviews and discovered that the workers at the brewery were offered free ale while they worked, so they did not drink the water.  (Water from the well was used to make the ale, but the fermentation process killed the cholera germs.)  And the water from the contaminated Broad Street pump was popular with many Soho residents who, despite living closer to other public pumps, walked the extra distance because the "water tasted better".

Snow took his evidence to the public health officials who all but laughed at his novel ideas.  Still—if only to help pacify the hysteria—they ordered the removal of the pump's handle, effectively shutting down the well.

The popular story is that this immediately stopped the epidemic and public officials immediately recognized that Snow was correct.  Neither of these stories is actually correct.  By the time the well handle was removed, the epidemic was all but over, the contamination within the well was probably flushed out by this time.

Nor did the public officials change their minds about miasma.  Following the epidemic, public officials scoured Soho looking for the reason the outbreak had been so violent.  They focused their attentions on ventilation of homes, adequate windows, and looking for peculiar smells and odors.  It was only decades later than Snow's work began to be appreciated.  Today it is recognized as the beginning of the study of epidemiology.

Even less well remembered is that while Snow's insistence on having the pump handle removed did not really stop the cholera outbreak, it probably did stop the "next outbreak".  The very day the pump handle was removed, the infant's father came down with cholera.  And that cesspool was still leaking into the well.

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