The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World

by Steven Johnson

In late June 1866, a husband and wife living in Bromley-by-Bow in East London fell ill with cholera and died a few days later. Within a week a terrible outbreak of cholera erupted in the East End—the worst the city had seen since the ravages of 1853–1854. By the end of August, more than four thousand people had died. This time it was William Farr who did the first round of detective work. Puzzled by the sudden explosion of cholera in the city after a decade of relative dormancy, Farr thought of his old sparring partner, John Snow, and his surveys of the South London water companies that had brought Snow so regularly to the Registrar-General’s Office. Farr decided to break down these new deaths along water-supply lines, and when he did, the pattern was unmistakable. The great majority of the dead had been customers of the East London Water Company. This time around, Farr wouldn’t waste time with miasmatic objections. He didn’t know how the East London supply had been contaminated, but clearly there was something deadly in that water. To waste time would be to condemn untold thousands to their deaths. Farr immediately ordered that notices be posted in the area advising residents not to drink “any water which has not been previously boiled.”

Radcliffe and Whitehead, along with other investigators, quickly uncovered a number of negligent practices at the East London company that had allowed the nearby River Lea to contaminate the groundwater around the company’s reservoir at Old Ford. Eventually, the index cases at Bromley-by-Bow were tracked down; the doomed couple’s water closet turned out to empty into the River Lea less than a mile from the Old Ford reservoir. In the end, the link to the East London water supply proved to be even more statistically pronounced than the link to the Broad Street pump had been in 1854. Ninety-three percent of the dead were eventually found to be East London Water customers.

Shortly after discovering the tuberculosis bacillus, the German scientist Robert Koch isolated Vibrio cholerae while working in Egypt in 1883. Koch had inadvertently replicated Pacini’s discovery of thirty years earlier, but the Italian’s work had been ignored by the scientific establishment, and so it was Koch who won the initial round of acclaim for identifying the agent that had caused so much trauma over the preceding century. History would come around to the Italian, though. In 1965, Vibrio cholerae was formally renamed Vibrio cholerae Pacini 1854.

Establishing sanitary water supplies and waste-removal systems became the central infrastructure project of every industrialized city on the planet. The appearance of the electrical grid, around the turn of the century, tends to attract more attention, but it was the building of the invisible grid of sewer lines and freshwater pipes that made the modern city safe for the endless consumer delights that electricity would bring.

By the 1930s, cholera had been reduced to an anomaly in the world’s industrialized cities. The great killer of the nineteenth-century metropolis had been tamed by a combination of science, medicine, and engineering. In the developing world, however, the disease continues to be a serious threat. A strain of V. cholerae known as “El Tor” killed thousands in India and Bangladesh in the 1960s and 1970s. An outbreak in South America in the early 1990s infected more than a million people, killing at least ten thousand. In the summer of 2003, damage to the water-supply system from the Iraq War triggered an outbreak of cholera in Basra.

In the Broad Street outbreak of cholera not only did Mr. Whitehead faithfully discharge the duties of a parish priest, but by a subsequent inquiry, unique in character and extending over four months…he laid the first solid groundwork of the doctrine that cholera may be propagated through the medium of drinking water…. This doctrine, now fully accepted in medicine, was originally advanced by the late Dr. Snow; but to Mr. Whitehead unquestionably belongs the honour of having first shown with anything approaching to conclusiveness the high degree of probability attaching to it.

Henry Whitehead died in 1896, at the age of seventy. Until death, a portrait of his old friend John Snow hung in his study—to remind him, as Whitehead put it, “that in any profession the highest order of work is achieved, not by fussy empirical demands for ‘something to be done,’ but by patient study of the eternal laws.”

On Broad Street itself, only one business has remained constant over the century and a half that separates us from those terrible days in September 1854. You can still buy a pint of beer at the pub on the corner of Cambridge Street, not fifteen steps from the site of the pump that once nearly destroyed the neighborhood. Only the name of the pub has changed. It is now called The John Snow.

Broad Street marked the first time in history when a reasonable person might have surveyed the state of urban life and come to the conclusion that cities would someday become great conquerers of disease. Until then, it looked like a losing battle all the way.

century city faces is a holdover from the Cold War: nuclear weapons. The doomsday scenarios are familiar enough: A megaton hydrogen bomb—too big for “suitcase bombs” but much smaller than today’s twenty-five-megaton state-of-the-art weapons—detonated at the site of the Broad Street pump vaporizes the entire area from the western edge of Hyde Park to Waterloo Bridge. A weekday attack would effectively wipe out the entire British government, reducing the Houses of Parliament and 10 Downing Street to radioactive ash. Most of London’s landmarks—Buckingham Palace, Big Ben, Westminster Abbey—would simply cease to exist. A wider zone extending out to Chelsea and Kensington and to the eastern edge of the old City would suffer 98 percent loss of life. Move a few miles farther out—up to Camden Town, out to Notting Hill or the East End—and half the population dies, with most buildings damaged beyond recognition. Anyone who happens to see the blast directly is blinded for life; most survivors suffer hideous radiation sickness that makes them envy the dead. As you move out from Ground Zero, the fallout leaves a vast wake of elevated cancer occurrences and genetic defects.

why are health officials in London and Washington and Rome worried about poultry workers in Thailand? Why, indeed, are these officials worried about avian flu in the first place? Because microbial life has an uncanny knack for mutation and innovation. All the world needs is for a single strain of H5N1 to somehow mutate into a form that is transmissible between humans, and that virus could unleash a pandemic that could easily rival the 1918 influenza pandemic, which killed as many as 100 million people worldwide.

IT IS CONCEIVABLE, THEN, THAT A LIVING ORGANISM—whether the product of evolution or genetic engineering—could threaten our great transformation into a city-planet. But there is reason for hope. We have a window of a few decades where DNA-based microbes will retain the capability of unleashing a cascading epidemic that kills a significant portion of humanity. But at a certain point—perhaps ten years from now, perhaps fifty—the window may well close, and the threat may subside, just as other, more specific, biological threats have subsided in the past: polio, smallpox, chicken pox.