Outbreak! Plagues That Changed History

by Bryn Barnard

  “Virgin soil” epidemics like this occurred wherever the Europeans set foot in the Americas. By 1527, the disease had spread south to the Inca Empire, killing the emperor and about 100,000 of his subjects. The epidemic sparked a civil war that had barely ended in 1532 when Spanish conquistador Francisco Pizarro arrived with about six hundred men. They captured the new emperor, Atahuallpa, ransomed him for a roomful of gold, then killed him. By chance, they also imported a second smallpox epidemic that killed so many Incans that fields were left uncultivated. Still more people died of famine. By the end of the sixteenth century, three-quarters of the Incans were dead. Meanwhile, in Brazil, the Portuguese were introducing the natives of the Amazon to Christianity and smallpox. The Indians died by the tens of thousands. Across the Americas, conqueror and conquered agreed that God was on the side of the invulnerable Europeans. It perplexed religious leaders, however, that though terrified natives converted to Christianity in droves, smallpox kept killing them.

  The Blessed Pox

  Smallpox was essential to the English and French conquest of North America. In 1617, three years before the arrival of the Pilgrims at Plymouth, a virgin soil epidemic passed through what would become New England, killing 90 to 94 percent of the inhabitants. The Pilgrims found a nearly empty land of abandoned villages and fields covered with the bones of the dead. Smallpox returned again and again, making the first fifty years of British colonization a virtual cakewalk: they could take what they wanted with little resistance. No wonder King George III called the disease “the Blessed Pox.” Smallpox moved westward across the continent ahead of the pioneers in a great wave of death.

  These epidemics were not always accidental. In 1763, during the final years of the French and Indian Wars, General Jeffrey Amherst, commander of the British forces, recommended a gift of smallpox-laced blankets to jumpstart an epidemic among Native Americans. His goal was genocide, or as he put it, to “… Extirpate this Execrable Race.” This is only the most notorious instance of British and American biological warfare against the natives.

  By the time English explorer George Vancouver cruised Puget Sound in 1792, the villages there were deserted, the beaches littered with skeletons. Smallpox had crossed the continent ahead of him.

  Not so blessed

  Unlike the plague bacterium, smallpox is a virus that has no host other than humans. An epidemic can only spread from person to person. In the densely populated cities of Europe, smallpox moved through the population at a pace that ensured someone was always infected, so that each new generation of susceptible babies got exposed. In this continuous “chain of infection,” one got the disease, passed it on, and survived or died. Most city folk who made it to adulthood were invulnerable to smallpox outbreaks for the rest of their lives.

  After the first generation of colonists established themselves in the New World, smallpox became nearly as bad a problem for their children as it was for the natives they were trying to exterminate. America’s colonial settlements were sparsely populated. Once smallpox had burned through all the susceptible people in a rural community, the chain of infection was broken. Smallpox could vanish completely for a generation. Only after enough vulnerable new hosts were born would a chance encounter with an infected individual start another epidemic. Between 1636 and 1717, Boston suffered seven separate smallpox epidemics.

  Europeans tried the usual unproductive methods to stop smallpox—bleeding, enemas, purgatives, and prayer. They also used quarantine to some effect. But Asia and Africa already had a preventative that worked. For centuries, the Chinese had been using inoculation: deliberate infection with smallpox to create a mild form of the illness. In the Chinese procedure, smallpox scabs were ground into powder and blown up a person’s nose. Indians, Africans, and Turks used another variant: injecting scab power or smallpox pus directly into a wound in the skin. Either way, the patient would get sick, recover, and be immune for life. Inoculation had disadvantages: once inoculated, a person was fully infectious and could get others sick. Worse, one in fifty would die—not great odds, but better than those of an actual epidemic.

  Variolization was practiced for centuries in the Far East, the Middle East, and Africa before the Europeans adopted the technique to immunize people against smallpox. In the Chinese version, dried smallpox scabs were blown up a patient’s nose, causing a mild case of the illness. People so treated had a one-in-fifty chance of dying. Survivors were immune for life.

  Who wants to be first?

  Inoculation was also called variolization, from variola, the official European term for smallpox. Variola was derived from the Latin varius (“spotted”) or varus (“pimple”). It came to be called “the small pox” to distinguish the disease from the symptoms of “the great pox,” a very different illness that appeared in Europe soon after Columbus returned from the New World. We call that disease syphilis.

  The variola virus

  Effective European efforts to prevent smallpox started in 1717 when Lady Mary Wortley Montagu, a smallpox survivor, learned about inoculation in Turkey. She called the procedure ingrafting. Later, it came to be called variolization. In 1718, Montagu had her son inoculated. In 1721, she returned to England and had her daughter inoculated. They survived and were proved immune. But British leaders resisted. Male doctors scoffed at a woman’s medical suggestion. Religious officials worried that without disease as a whip, people wouldn’t fear God. It took successful experimentation on prisoners and orphans and acceptance by Montagu’s friends in the British royal family to popularize inoculation. Meanwhile, on the other side of the Atlantic, Reverend Cotton Mather learned about the African version of the procedure from his slave Onesimus. Mather introduced variolization to Boston. By the Revolutionary War, George Washington would inoculate the entire Continental army.

  The epochal year in smallpox prevention, however, was 1796, when British doctor Edward Jenner proved that inoculation with the harmless vaccina (cowpox) virus prevented infection with smallpox. He called this procedure vaccination. His discovery was published in a pamphlet that was translated into German, French, Spanish, Dutch, Italian, and Latin. Vaccination quickly spread around the world, but it took nearly two more centuries to wipe out the disease. By 1977, a heroic decades-long campaign of global vaccination by the World Health Organization finally broke the last link in the smallpox infection chain. Smallpox was eradicated from the wild. The virus still exists, though it is confined to a freezer. Two, actually: one in the United States, the other in Russia.

  Too good to be true

  Survivors of certain infectious diseases are invulnerable to repeat epidemics. This immunity gives them the ultimate advantage. When the illness returns, they will remain healthy while others sicken and die. This difference between the immune and susceptible has sometimes had historically significant consequences. In the case of yellow fever, the significance was truly awesome: it helped bring an end to New World slavery.

  In the sixteenth century, Europe had conquered the Aztecs, the Incas, and the indigenous people of the Caribbean and much of Amazonia and eastern North America. The New World seemed an inexhaustible supply of wealth: land for the taking, gold and silver from its mines, food from its farms, hides, feathers, pelts, wood, and dyes from its forests. Most importantly, the New World was an astonishingly fertile place to plant a valuable Old World crop: sugar. Sugar plantations needed a source of plentiful, cheap workers—preferably slaves. Europe itself wouldn’t do; the continent was still underpopulated from the Black Death. With demand for labor exceeding supply, peasants had power: wages were going up. Nor was the New World a potential slave-labor pool, for European depredation and disease had nearly wiped out the Native American population.

  The obvious alternative was Africa, a continent European explorers and colonists were just beginning to exploit. Africa already had a bustling slave trade to satisfy local and Muslim demand. The Europeans simply redirected the flow across the Atlantic and opened the spigot full blast. The deadly irony of this
choice would become apparent too late. Along with the estimated twenty million Africans enslaved and shipped to America for European greed came yellow fever, an African disease to which most slaves were immune but slave owners were not. The illness would prove to be slavery’s undoing, first in the Caribbean, then in North and South America. Later, the disease would also play an important role in the United States’ efforts to project its power throughout the region.

  Welcome home

  Human beings have lived in Africa longer than on any other continent. Pathogens that live there too have become exquisitely adapted to exploiting us. Malaria, yellow fever, river blindness, and elephantiasis are just a few of the diseases that coevolved with people, fine-tuning their life cycles to our own. Thousands of years ago, when many of our ancestors left Africa to populate temperate regions, they managed to leave many of these parasites behind. But when Europeans returned to conquer Africa, the microbes were waiting. In West Africa, tropical diseases killed so many Europeans the region was nicknamed “the white man’s grave.” Within a year of arrival, most would-be conquerors weren’t running plantations or sipping gin on the veranda, they were composting in the soil. The image of the European explorer or missionary dying in his tent from some tropical illness was so common it became a literary cliché. “Beware, beware the Bight of Benin,” warned one British rhyme about West Africa. “One comes out where fifty went in.”

  Yellow fever proved an exceptionally portable African disease. On ships leaving Africa for the New World, the fever would usually strike a week or so into the voyage. Mild cases would feel like the flu: the symptoms would pass and the host would recover. In severe cases, however, the illness would progress from fever, blinding headaches, chills, and intense muscle pain to bleeding from the nose and mouth. Blood would collect in the stomach, coagulate and darken, and exit as yellow fever’s unmistakable black vomit. Eventually the liver would fail, turning the skin a jaundiced yellow. Death would follow.

  Super slaves

  Yellow fever scythed through ship after ship sailing from Africa to the New World. Sometimes entire crews perished from yellow fever. On average, one-fifth were done in. When a fever-struck ship arrived in port, it was often quarantined and forced to fly a yellow flag or “jack.” Yellow jack became the English maritime name for the disease. As with other mysterious illnesses, Europeans tried fervent prayer and the usual Galenic cures: bleeding, purgatives, enemas, cold-water baths, or aromatic talismans to ward off the miasmas thought to cause the disease. As usual, nothing worked.

  Yellow fever would often break out on slave ships at sea, sickening and killing the European crew. Adult Africans who had survived the disease as children were immune, a black invulnerability whites found mystifying.

  Almost as mysterious as yellow fever itself was the fact that enslaved Africans seemed invulnerable to the illness. This was a powerful advantage. When white slavers sickened, blacks could revolt. The famous slave mutiny aboard the ship Amistad, for example, was probably made possible by yellow fever. Later, when the disease ravaged Europeans running the plantations of the New World, Africans had multiple opportunities to escape, resist, or attack their tormentors.

  How to explain this difference between the races? Whites didn’t understand that blacks, having survived yellow fever in Africa as children, now enjoyed life-long immunity to the disease. Instead, the same people who had once concluded that Native Americans were inferior because they died from European disease now assured themselves that blacks were suited to slavery because they were immune to yellow fever. The logic of bigotry is a marvelously malleable thing.

  Sweet vengeance

  Yellow fever repeatedly harassed European efforts to exploit the Americas. The illness effectively closed the Amazonian basin to European exploitation and repeatedly devastated the plantation economy of the southern United States. (Remarkably, though ships also traveled from Africa to Asia, yellow fever never took hold there.)

  One of the earliest New World yellow fever outbreaks was on the British Caribbean island of Barbados. This efficient sugar machine was ravaged by yellow fever from 1647 to 1650 and again in 1690, with over 10,000 people killed.

  Even more profitable and more deadly was the French slave colony of Haiti (then called Saint Domingue) on the island of Hispaniola. It is hard to believe that what is now the poorest, most environmentally devastated place in the Western Hemisphere was once the most lucrative colony in the world. Haiti produced more sugar than all the other Caribbean islands combined. It made more money for France than England’s revenues from all thirteen American colonies. But in 1789, the French Revolution toppled the monarchy. Ideas of “Liberté! Fraternité! Egalité!” filtered to Haiti. By this time, so many Africans had been imported to the island that slaves now outnumbered their white masters fifteen to one. In 1791, Haiti’s slaves revolted. Hundreds of thousands rose up, torched cities, burned plantations, and massacred whites. In 1794, France’s revolutionary government abolished slavery throughout the colonies. In 1802, however, France’s new ruler, Napoleon Bonaparte, tried to reassert control of Haiti and reestablish slavery. He envisioned an even more profitable colony, supplied with food from France’s Louisiana Territory. Napoleon sent a massive amphibious force commanded by his brother-in-law, General Charles leClerc. The soldiers managed to kill over 150,000 slaves. But 50,000 French soldiers also died (including leClerc), mostly from yellow fever.

  Imagine trying to fight an enemy impervious to an invisible force that made your comrades become feverish and jaundiced, spew black vomit, and die. The French could sustain neither their morale nor the invasion. Napoleon went on to acknowledge an independent Haiti, and in 1803 sold France’s claim to the now apparently useless Louisiana Territory to the United States.

  After the African slaves of Haiti revolted and massacred their French masters, Napoleon Bonaparte tried to reassert control. In 1803, his massive amphibious force was defeated. Some 50,000 French soldiers died, mostly from yellow fever.

  In 1804, Haiti declared itself a republic. In 1816, the new nation helped the South American general Simón Bolívar mount the invasion that ultimately ended the Spanish empire in the Americas. In return, Bolívar promised to free his own slaves and outlaw slavery in the lands he liberated.

  Elsewhere in the Caribbean and the southern United States, slave revolts increased. So did repressive legislation designed to keep slaves in their place, and an abolitionist movement to set them free. One ahead-of-his-time British planter suggested that rethinking the slavery “brand” would solve the problem. Call them “plantation assistants,” he suggested, and abolitionists would stop complaining. No one yet realized that with a free Haiti as an example, slavery was finished in the Western Hemisphere. Abolitionist pressure killed British slavery in 1838. The American Civil War drove a stake through the heart of American slavery in 1865. No one thanked yellow fever for starting the revolution.

  Define fiasco

  Even after the demise of slavery, yellow fever continued to have an impact on the New World. In 1881, French engineers began construction of a sea-level canal through the Isthmus of Panama. The project was led by renowned French diplomat-impresario Count Ferdinand de Lesseps, who had successfully managed the construction of the Suez Canal across Egypt. Unlike Egypt, however, Panama had a deadly reputation for both malaria and yellow fever. De Lesseps downplayed this problem. To reduce miasmas still thought to cause the disease, the French built tidy, clean, well-built worker barracks with elaborate ornamental gardens. Even before construction began, however, workers started dying from malaria and yellow fever. Since miasma was accounted for, a variety of sin-based explanations were proposed: drinking, gambling, even embezzling were all suspected of causing disease. One engineer, out to prove that immorality was the culprit, brought his upstanding family to Panama. Yellow fever killed them all. Finally, in 1889, with thirty thousand workers dead, billions spent, the canal unbuilt, and de Lessep’s reputation in tatters, the project was abandone
d.

  A good guess

  In 1880, a year before de Lesseps embarked on his Panamanian folly, Dr. Carlos Finlay suggested that Aedes mosquitoes might transmit yellow fever. Finlay observed that healthy humans bitten by mosquitoes that had previously fed on yellow fever sufferers also caught the disease. Finlay’s hypothesis was ignored for decades, but he was exactly right.

  In essence, a mosquito is an airborne syringe. Mosquitoes are equipped with a long hollow proboscis for drinking liquids, a tube for injecting saliva, and a set of cutting stylets for making a wound. Only females use this apparatus to drink blood, and then only when they need to nourish egg production. (For regular meals, mosquitoes drink nectar or honeydew.) When females need a blood meal, they land on a host, poke a hole through the skin, nick a capillary, inject some anticoagulant to make the blood flow, and drink up. Of the 2,500 kinds of mosquitoes, most prefer to dine on other animals. Only a small minority vampirize people. Of the deadly illnesses mosquitoes carry, only a handful affect us. But they’re doozies, including ma-laria, dengue fever, encephalitis, West Nile virus, and yellow fever. Since the Stone Age, the mosquito has probably killed more people than any other creature.