The Ghost Map

by Steven Johnson

  In practice, it’s not impossible for physical contact with a cholera victim to transmit the disease, but the chance of transmission is slight. In handling soiled linens, for instance, an invisible collection of V. cholerae might cluster on a fingertip, where, left unwashed, they might find their way into your mouth during a meal, and shortly thereafter begin their deadly multiplication in your small intestine. From the cholera’s point of view, however, this is generally an inefficient way to reproduce: only a small number of people are likely to touch the immediate waste products of another human, particularly one suffering from such a violent and deadly illness. And even if a few lucky bacteria do manage to attach themselves to an errant finger, there’s no guarantee that they’ll survive long enough to make it to the small intestine.

  For thousands of years, cholera was largely kept in check by these two factors: humans on the whole were disinclined to knowingly consume each other’s excrement; and, on those rare occasions when they did accidentally ingest human waste, the cycle wasn’t likely to happen again, thus keeping the bacteria from finding a tipping point where it spread at ever-increasing rates through the population, the way more easily transmitted diseases, like influenza or smallpox, famously do.

  But then, after countless years fighting to survive through the few transmission routes available, V. cholerae got a lucky break. Humans began gathering in urban areas with population densities that exceeded anything in the historical record: fifty people crammed into a four-story townhouse, four hundred to an acre. Cities became overwhelmed with their human filth. And those very cities were increasingly connected by the shipping routes of the grand empires and corporations of the day. When Prince Albert first announced his idea for a Great Exhibition, his speech included these utopian lines: “We are living at a period of most wonderful transition, which tends rapidly to accomplish that great era to which, indeed, all history points: the realisation of the unity of mankind.” Mankind was no doubt becoming more unified, but the results were often far from wonderful. The sanitary conditions of Delhi could directly affect the conditions of London and Paris. It wasn’t just mankind that was being unified; it was also mankind’s small intestine.

  Inevitably, in these sprawling new metropolitan spaces, with their global networks of commerce, lines were crossed: drinking water became laced with sewage. Ingesting small particles of human waste went from being an anomaly to a staple of everyday life. This was good news for V. cholerae.

  The contamination of drinking water in dense urban settlements did not merely affect the number of V. cholerae circulating through the small intestines of mankind. It also greatly increased the lethality of the bacteria. This is an evolutionary principle that has long been observed in populations of disease-spreading microbes. Bacteria and viruses evolve at much faster rates than humans do, for several reasons. For one, bacterial life cycles are incredibly fast: a single bacterium can produce a million offspring in a matter of hours. Each new generation opens up new possibilities for genetic innovation, either by new combinations of existing genes or by random mutations. Human genetic change is several orders of magnitude slower; we have to go through a whole fifteen-year process of maturation before we can even think about passing our genes to a new generation.

  The bacteria have another weapon in their arsenal. They are not limited to passing on their genes in the controlled, linear fashion that all multicellular organisms do. It’s much more of a free-for-all with the microbes. A random sequence of DNA can float into a neighboring bacterial cell and be immediately enlisted in some crucial new function. We’re so accustomed to the vertical transmission of DNA from parent to child that the whole idea of borrowing small bits of code seems preposterous, but that is simply the bias of our eukaryotic existence. In the invisible kingdom of viruses and bacteria, genes move in a far more indiscriminate fashion, creating many disastrous new combinations, of course, but also spreading innovative strategies at a much faster clip. As Lynn Margulis writes: “All the world’s bacteria essentially have access to a single gene pool and hence to the adaptive mechanisms of the entire bacterial kingdom. The speed of recombination over that of mutation is superior: it could take eukaryotic organisms a million years to adjust to a change on a worldwide scale that bacteria can accommodate in a few years.”

  Bacteria like Vibrio cholerae, then, are eminently capable of evolving rapid new characteristics in response to changes in their environment—particularly a change that makes it significantly easier for them to reproduce themselves. Normally, an organism like V. cholerae faces a difficult cost-benefit analysis: a particularly lethal strain can make untold billions of copies of itself in a matter of hours, but that reproductive success usually kills off the human body that made that reproduction possible. If those billion copies don’t find their way into another intestinal tract quickly, the whole process is for naught; the genes for increased lethality are unable to make new copies of themselves. In environments where the risk of transmission is low, the better strategy is to pursue a low-intensity attack on the human host: reproduce in smaller numbers, and keep the human alive longer, in hopes that over time some bacterial cells will find their way to another intestine, where the process can start all over again.

  But a dense urban settlement with contaminated water supplies eliminates V. cholerae’s dilemma. There’s no incentive not to reproduce as violently as possible—and thus kill your host as quickly as possible—because there’s every likelihood that the evacuations from the current host will be swiftly routed into the intestinal tract of a new one. The bacterium can invest all its energy in sheer reproductive volume, and forget about longevity.

  It goes without saying that the bacteria are not in any way conscious of developing this strategy. The strategy evolves on its own, as the overall population balance of V. cholerae changes. In a low-transmission environment, lethal strains die out, and mild ones come to dominate the population. In high-transmission environments, the lethal strains quickly outnumber the mild ones. No single bacterium is aware of the cost-benefit analysis, but thanks to their amazing capacity for adaptation, they’re able to make the analysis as a group, each isolated life and death serving a kind of vote in a distributed microbial assembly. There is no consciousness in the lowly bacterium. But there is a kind of group intelligence nonetheless.

  Besides, even human consciousness has its limits. It tends to be very acute on the scales of human existence, but as ignorant as the bacteria on other scales. When the citizens of London and other great cities first began gathering together in such extraordinary number, when they began building elaborate mechanisms for storing and removing their waste, and pulling drinking water from their rivers, they did so with conscious awareness of their actions, with some clear strategy in mind. But they were entirely unaware of the impact that those decisions would have among the microbes: not just in making the bacteria more numerous, but also in transforming their very genetic code. The Londoner enjoying his new water closet or his expensive private water supply from the Southwark Water Company was not just engineering his private life to make it more convenient and luxurious. He was also, unwittingly, reengineering the DNA of V. cholerae with his actions. He was making it into a more efficient killer.

  THE TRAGIC IRONY OF CHOLERA IS THAT THE DISEASE HAS A shockingly sensible and low-tech cure: water. Cholera victims who are given water and electrolytes via intravenous and oral therapies reliably survive the illness, to the point where numerous studies have deliberately infected volunteers with the disease to study its effects, knowing that the rehydration program will transform the disease into merely an uncomfortable bout of diarrhea. You would think that the water cure might have occurred to some of the physicians of the day: the ill were discharging prodigious amounts of water, after all. If you were looking for a cure, wouldn’t it be logical to start with restoring some of those lost fluids? And indeed, one British doctor, Thomas Latta, hit upon this precise cure in 1832, months after the first outbreak, injecting salt
y water into the veins of the victims. Latta’s approach differed from the modern treatment only in terms of quantity: liters of water are necessary to ensure a full recovery.

  Tragically, Latta’s insight was lost in the swarming mass of cholera cures that emerged in the subsequent decades. Despite all the technological advances of the Industrial Age, Victorian medicine was hardly a triumph of the scientific method. Reading through the newspapers and medical journals of the day, what stands out is not just the breadth of remedies proposed, but the breadth of people involved in the discussion: surgeons, nurses, patent medicine quacks, public-health authorities, armchair chemists, all writing the Times and the Globe (or buying classified advertising there) with news of the dependable cure they had concocted.

  Those endless notices reflect a strange historical overlap, one we have largely outgrown—the period after the rise of mass communications but before the emergence of a specialized medical science. Ordinary people had long cultivated their folk remedies and homespun diagnoses, but until newspapers came along, they didn’t have a forum beyond word of mouth to share their discoveries. At the same time, the medical division of labor that we now largely take for granted—researchers analyze diseases and potential cures, doctors prescribe those cures based on their best assessment of the research—had only reached an embryonic state in the Victorian age. There was a growing medical establishment—best embodied by the prominent journal The Lancet—but its authority was hardly supreme. You didn’t need an academic degree to share your cure for rheumatism or thyroid cancer with the world. For the most part, this meant that the newspapers of the day were filled with sometimes comic, and almost always useless, promises of easy cures for diseases that proved to be far more intractable than the quacks suggested. But that anarchic system also made it possible for genuine visionaries to route around the establishment, particularly when the establishment had its scientific head in the sand.

  The prominence of quack cures also had an unexpected side effect: it helped create an entire rhetoric of advertising—as well as a business model for newspapers and magazines—that has lasted for more than a century. By the end of the 1800s, patent-medicine manufacturers were the leading advertisers in the newspaper business, and as the historian Tom Standage observes, they were “among the first to recognize the importance of trademarks and advertising, of slogans, logos.… Since the remedies themselves usually cost very little to make, it made sense to spend money on marketing.” It has become a cliché to say that we now live in a society where image is valued over substance, where our desires are continually stoked by the illusory fuel of marketing messages. In a real sense that condition dates back to those now quaint notices running in the columns of Victorian newspapers, promising an endless litany of cures bottled in one marvelously inexpensive elixir.

  Not surprisingly, the patent-medicine industry was eager to provide a cure for the most menacing disease of the nineteenth century. A naïve reader of the London Times classifieds in August of 1854 might have naturally assumed that the cholera was on its way out, given all the cures that seemed readily available:

  FEVER and CHOLERA.—The air of every sick room should be purified by using SAUNDER’S ANTI-MEPHITIC FLUID. This powerful disinfectant destroys foul smells in a moment, and impregnates the air with a refreshing fragrance.—J.T. Saunders, perfumer, 316B, Oxford-street, Regent-circus; and all druggists and perfumers. Price 1s.

  As laughable as the patent-medicine adverts seem to us today, they nonetheless provoked irate letters complaining about the injustice of keeping these expensive cures out of reach of the lower classes:

  Sir,—I have observed lately several letters in your influential journal, treating upon the present much-talked-of subject—the enormous price of castor oil as retailed by the druggists.… One man in this town [has] boldly come forward and made a public announcement, in the shape of placards upon the walls, that he is prepared to sell the finest cold-drawn castor oil at 1d. per ounce, and it is to be hoped that his example will be universally followed. Sure, Sir, when a druggist himself is candid enough to publish to the world that he can afford to sell this article at 1d. per ounce instead of 3d. and by so doing have a sufficient profit thereby, can there now be any doubt whatever in the minds of the people that this class of tradesman have for many years past been reaping a great harvest by retailing castor oil to the poor at such immense gains.

  You can see in these sentences the beginning of another modern sensibility: the outrage that is now directed against the price gouging of multinational drug companies. But at least Big Pharma is, more often than not, selling something that actually works. It is hard to say which would be a worse offense: selling castor oil with such high profit margins, or giving it away as a charitable act. At least the high prices discouraged people from employing the noxious stuff.

  One step up the food chain were the letters to the Times, often written by accredited medical men, offering up their remedy (or disputing another’s) for less obviously commercial ends. In the late summer of 1854, the surgeon-in-chief of the city police, G. B. Childs, had taken to writing the Times with descriptions of his fail-safe remedy for cholera’s most telltale symptom: diarrhea. This is his letter from the eighteenth of August:

  Will you… kindly allow me a space in your columns, not only to reiterate what I have already with reference to ether and laudanum, but to explain how, in my opinion, these remedies act when taken into the stomach? If any corroborative testimony of its efficacy be further required, I would ask those who might be skeptical of its merits to call at any one of the police stations in the city of London, where a supply of the medicine is kept and satisfy themselves of the estimation in which it is held by the members of the force.… You want something which will act immediately without requiring the slow, and in these cases uncertain, process of digestion. If the properties of opium are valuable, and they are acknowledged to be such by all authorities, the sooner these properties are brought into active operation the better.… In conclusion, Sir, I beg to observe that in submitting these remedies to your numerous readers I feel that, as a public officer, I am only discharging a public duty.

  Formally, those closing solemn statements are typical of the genre, and of course their solemnity plays against the modern reader’s amusement at the remedy itself. After all, we have here a chief law enforcement official writing into the daily paper essentially to encourage people to ingest heroin to treat their upset stomachs—and if the readers don’t believe him, they should head down to the nearby squad house to hear firsthand how highly regarded the “medicine” is by the police force. Not exactly a “war on drugs” sentiment, although not entirely without merit medically: constipation is a reliable side effect of opiate abuse.

  Cholera remedies were a running dialogue in the papers of the day, a source of endless debate. One M.D. would write in endorsing his cocktail of linseed oil and hot compresses on Tuesday, and by Thursday another would be running off a list of patients who had died after following precisely such a treatment.

  Sir,—Induced by the very favourable results of the use of castor oil in cholera, as reported by Dr. Johnson, I have just put his practice to the test of experience, and I regret to say with signal failure….

  Sir,—Let me entreat your metropolitan readers not to be led by the letter of your correspondent into the belief that smoke is in any way a preventative of cholera, or can in any degree influence the prevalence of epidemic disease….

  The constant squabbling between medical authorities in the papers eventually hit a point of self-parody. The week of the Broad Street outbreak, Punch went to press with a lacerating editorial titled “Who Shall Decide When Doctors Disagree?”

  It really is nauseating to witness the quantity of doctor’s stuff that is allowed to run down the columns of the newspapers. It will be necessary at last to proceed against the public press as a public nuisance if we have much more of the “foul and offensive matter” circulating under our noses every day at
our breakfast tables to an extent highly dangerous to the health, the patience, and the nerves of the reading community. If the doctors who write to the papers would agree in their prescriptions for cholera, the public might feel grateful for the trouble taken, but when one medical man’s “infallible medicine” is another man’s “deadly poison,” and the specific of to-day is denounced as the fatal drug of to-morrow, we are puzzled and alarmed at the risk we run in following the doctors’ contradictory directions.

  Ordinary doctors possessed no less unanimity in their treatment of cholera than the patent-medicine impresarios or the newspaper letter-writers. Sometimes the cholera was treated with leeches, based on the humoral theory that whatever seemed wrong with the patient should be removed from the patient: if the cholera sufferer’s blood was unusually thick, thanks to dehydration, then the patient needed to lose more blood. Contrary to G. B. Childs’ advice, many doctors prescribed laxatives to combat a disease that was already expelling fluids from the body at a lethal rate. Purgatives like castor oil or rhubarb were widely prescribed. Physicians were also inclined to recommend brandy as a treatment, despite its known dehydrating effects. While these were not quite examples of the cure being worse than the disease—cholera set the bar quite high, as diseases go—many of the proposed remedies exacerbated the physiological crisis that cholera induced. The few positive effects, such as they were, were mostly placebo in nature. And of course, in this elaborate mix of homespun remedies, commercial elixirs, and pseudoscientific prescriptions you would almost never find the real advice that the patients needed to hear: rehydrate.

  ON FRIDAY MORNING, THE GROWING SENSE OF DREAD HAD not yet expanded beyond the borders of the Golden Square neighborhood. The heat wave had finally broken, and the rest of the city savored the cool, clear weather. There was no way to know that in their midst a terrible outbreak was claiming its first victims. The Morning Chronicle’s one item about cholera sounded an upbeat note, reflecting on its diminished presence on the front lines of the Crimean War: “Having at length emerged from the dangers of the month of August, we may hope to behold the abatement of pestilence at the seat of war, and the resumption of active operations. There seems to be little doubt that cholera has done its worst, and that its ravages in the allied army are very considerably mitigated, both in extent and virulence; and the fleet also, which was attacked somewhat later, appears to have now passed the crisis of the disorder.”