Single-celled Plasmodium parasites burst out of dying red blood cells, beginning the assault on the body that leads to full-blown malaria.
IN HIS ACCOUNT OF HIS SECOND VOYAGE TO the Caribbean, Christopher Columbus wrote that “all my people went ashore to settle, and everyone realized that it rained a lot. They became gravely ill from çiçiones.” The term çiçiones refers to a bout of illness that begins with chills, followed by days of high fever and weakness. One of the many diseases that cause chills and fevers is malaria, which is spread through mosquito bites.
Did Columbus’s men get malaria? If so, they brought it with them. Malaria in humans did not exist in the Americas before Europeans arrived. Historians do not know for certain that the disease that attacked Columbus’s people in 1493 was malaria, but if just one of his men had malaria and suffered an attack after landing in Hispaniola, it would have taken only one bite by the right type of mosquito to spread the disease from that victim to others—and those mosquitoes are abundant on Hispaniola.
Malaria is responsible for unimaginable suffering. In spite of a worldwide effort to wipe out malaria that began in the 1950s, the disease still infects some twenty million people each year and kills more than six hundred thousand. Most of those who die are children under the age of five. Those who don’t die can be sickened and weakened for months, even with modern medical care. The disease can lurk in the body for months and then emerge with another full-scale attack. So many people in Africa suffer so often from malaria that economists think the disease has seriously slowed the pace of development there.
As it does today, malaria played a huge role in the past. Its role was different from that of other diseases, and maybe larger. When Europeans brought smallpox and influenza to the Americas, they set off epidemics, sudden outbursts that shot through Indian towns and villages and then faded. Malaria became endemic, which means that it was always present in the landscape. Instead of coming in sudden, severe bursts, malaria was a constant, steady background to life.
Malaria and yellow fever (another disease brought to the Americas, also carried by mosquitoes) turned the Americas upside down. Before these diseases arrived, the most thickly populated area north of Mexico was what is now the southeastern United States—Georgia, the Carolinas, Alabama. To the south, the wet forests of southern Mexico, Central America, and the Amazon Basin held millions of people. After malaria and yellow fever, these previously healthful areas became inhospitable as the diseases thrived. The Indians who had lived there fled to safer ground.
Europeans who moved into the emptied real estate often died within a year. These deaths had a long-lasting effect. Even today, the places where European colonists couldn’t survive are poorer than places they found more healthful. That’s because Europeans created different institutions in disease areas than in healthful areas. In healthful areas, they built stable colonies that attracted settlers. The growing populations of these areas included farmers, craftspeople, and business owners. Schools, roads, hospitals, legal codes, and government systems were put in place. Disease areas, however, attracted smaller numbers of Europeans. There the colonizers had little interest in building functioning social and government institutions. Instead they focused on using native or captive labor to remove resources such as timber, precious metals, or crops that were grown on plantations and exported.
Disease played a part in how the labor force in the American colonies developed. Because malaria and yellow fever killed European and Indian workers in the tobacco and sugar plantations of the Americas, the colonists imported labor in the form of captive Africans—the human side of the Columbian Exchange. The ecological exchange, in the form of new diseases, led to the economic exchange, in the form of slavery. In turn, slavery had political effects that have continued to the present day.
It would be an exaggeration to say that malaria and yellow fever were responsible for the slave trade, or that they are the reason the weak, divided thirteen colonies won independence from mighty Great Britain in the Revolutionary War. Yet as you will see in this chapter, it would not be completely wrong, either.
In Columbus’s day, people did not realize that malaria was a specific disease. They thought of it as a collection of symptoms, and they believed it was caused by marshy or bad air. The English word malaria, in fact, comes from the Italian mal aria, meaning “evil or bad air.”
Malaria, however, is a disease with a complicated life cycle that was not understood until modern times. It is caused by two hundred or so species of microscopic parasites that plague countless types of reptiles, birds, and mammals. Four of those parasite species target human beings—and they are dishearteningly good at their jobs.
Each parasite consists of a single cell. It is injected into human flesh by the bite of a mosquito. Once in the body, the parasite pries open red blood cells and climbs inside. Floating around the circulatory system like passengers in submarines, the parasites reproduce in huge numbers inside the infected red blood cells. Eventually they burst out and pour into the bloodstream. Most of the parasites force their way into new red blood cells, but a few drift in the blood, waiting to be sucked up by a mosquito. When a mosquito takes in the parasite, the parasite reproduces again inside the insect. Parasites squirm into the mosquito’s saliva glands, where they wait to be injected into a new host when the mosquito bites someone.
Inside the human body, most of the infected red blood cells release their parasites at about the same time. Infection from a single malaria parasite can produce ten billion new ones. These huge assaults overwhelm the host’s immune system, setting off spasms of chills and fever. Eventually the host’s immune system beats back the attack, but within days a new attack takes place because some of the previous wave of parasites have hidden themselves inside red blood cells and produced a new generation of billions of parasites. This cycle repeats until the immune system finally defeats the parasite. It may not be a real victory, though. The parasites can hide in other corners of the body, only to emerge again weeks later. The sign of full-blown malaria is half a dozen episodes of chills and fever, followed by a short period of relief, and then another wave of attacks.
The two most widespread forms of malaria in humans are caused by the microorganisms Plasmodium vivax and Plasmodium falciparum. Their symptoms are similar, but they have different effects on the body. P. Falciparum can cut off circulation to the kidneys, lungs, brain, and other organs. Organ failure kills as many as one out of ten P. falciparum sufferers. P. vivax doesn’t destroy organs, which makes it less deadly, but during its attacks sufferers are weak, and vulnerable to other diseases. With both types of malaria, sufferers can be sick for months at a time, and they are infectious during attacks. A mosquito that bites a sick malaria sufferer can transfer the disease to others.
Plasmodium microorganisms are tropical and sensitive to temperature. The speed at which they can reproduce inside mosquitoes depends on the temperature of the outside air. As the days get colder, it takes the parasite longer and longer to reproduce, until it takes longer than the mosquito’s lifespan—which ends the cycle. Practically speaking, P. falciparum cannot survive and reproduce for long below temperatures of about 66 degrees Fahrenheit. P. vivax has a limit of about 59 degrees.
P. falciparum thrives in most of Africa. In Europe it gained a foothold only in the warmest areas: Greece, Italy, Portugal, and southern Spain. P. vivax, however, became endemic in most of Europe, including cooler northern places such as England, the Netherlands, and southern Scandinavia. P. falciparum came to the Americas from Africa and was spread by Africans. P. vivax came from Europe and was spread by Europeans. This difference had historic consequences.
Human malaria is carried only by mosquitoes in the Anopheles genus. (A genus is a group of closely related species.) Landscape engineering by humans in sixteenth-century England created the perfect conditions for Anopheles mosquitoes and vivax malaria to prosper—and be carried to the Americas by English colonists.
The mosquitoes that carry malaria, and the disease itself, seem to have been rare in England until the later sixteenth century. At that time, Queen Elizabeth I began encouraging landlords to drain marshes and other wetlands to create more farmland. A great deal of drainage work was done in the coastal wetlands of eastern and southeastern England. Much of this low, foggy landscape had been flooded regularly by the high tides of the North Sea, which washed away mosquito larvae before they could hatch into adult mosquitoes. The work of draining the wetlands blocked the sea but left the land dotted with pockets of standing water that were not scoured by the tides. These pools were the perfect habitat for Anopheles mosquitoes.
Farmers moved into the former marshlands, which were still soggy but now usable for farming. They heated their homes and barns during cold weather, providing a place for the mosquito, and the P. vivax parasites inside it, to survive the cold weather, ready to breed and spread the following spring. Church records show that in the 1570s, before the draining of the marshes, baptisms outnumbered burials in twenty-four wetland parishes. In other words, the population was rising. Two decades later, with draining in full swing, the trend had reversed. There were almost twice as many burials as baptisms. Population was booming in other parts of England, but these wetland parishes would not return to their earlier rates of growth for almost two centuries. Clergymen died in such numbers after being sent to southeast England that the region became known as Killpriest.
Draining the marshes of eastern and southeastern England set off an inferno of vivax malaria. The English wetlands were not the only area affected, however. There is good reason to think that vivax malaria traveled from there to the North American colonies. Information about the early colonists is sketchy and incomplete, but one researcher has estimated that about 60 percent of the first wave of English immigrants to North America came from nine counties in eastern and southeastern England—the country’s malaria belt.
One example is the hundred-plus colonists who began Jamestown. Fifty-nine of their birthplaces are known. Thirty-seven of those fifty-nine came from malaria-ridden counties. Even if most of them set off from higher, inland parts of the counties that had less malaria than the coastal wetlands, some of them would have come from the marshes. Those who didn’t come from the malaria zone usually passed through it just before departure, as their ships waited for weeks or even months at points along the Thames River that were malaria centers.
People in the midst of malarial attacks would seem to be unlikely candidates for a difficult sea voyage. Yet Plasmodium can hide inside a seemingly healthy person. Colonists could board their ships without symptoms, land in Chesapeake Bay country, and then be struck by the teeth-chattering chills and sweat-bursting fevers of malaria. At that point, unfortunately, they could pass the parasite to every mosquito that bit them—and waiting on the East Coast of North America were five Anopheles species that became the primary spreaders of the disease.
“In theory, one person could have established the parasite in the entire continent [of North America],” said Andrew Spielman, a malaria researcher at the Harvard School of Public Health. “It’s a bit like throwing darts. Bring enough sick people in contact with enough mosquitoes and sooner or later you’ll hit the bull’s-eye—you’ll establish malaria.”
Almost certainly some of the colonists at Jamestown, Virginia, were infectious. If the disease started there, it soon spread north. By 1657, John Winthrop, the governor of the Connecticut colony, was recording cases of malaria symptoms. Researchers now think that malaria entered the continent in the 1640s or even earlier. Conditions for the disease were perfect between 1606 and 1612, when low-lying coastal Virginia suffered a series of droughts. These droughts would have turned flowing streams into strings of little standing pools, the ideal habitat for mosquito larvae. The Jamestown settlement was founded in 1607, in the heart of the drought period.
Whenever malaria arrived, it rapidly made itself at home in Virginia. It became as unavoidable there as it was in the English marshes. Everyone expected new arrivals to get sick and to be fairly useless for the first year, until they were “seasoned”—in other words, until they had battled malaria and won. The battle often ended in the cemetery, however. During Jamestown’s first half century, as many as a third of new arrivals died within a year. After that, Virginians learned by trial and error to live with vivax. They avoided marshes and stayed indoors at dusk, when mosquitoes are most active. Malaria-related deaths among new arrivals fell from 20 or 30 percent around 1650 to 10 percent or lower around 1670. These numbers reflect a considerable improvement, but still much suffering.
The story of New Edinburgh shows the big role that disease played in colonization. You’ve probably never heard of New Edinburgh, even though it was a large, ambitious colonial venture. That’s because it was also a short-lived disaster.
New Edinburgh was meant to be a Scottish colony in Panama. The colony’s organizer claimed that the location, on the narrow strip of land that separates the Atlantic and Pacific Oceans, would let the colony control “at least two-thirds” of the Asia trade with Europe. Dazzled by this vision, more than fourteen hundred people in Scotland put money into a joint-stock venture, the same type of business organization that had founded Jamestown. Scotland was a poor nation. Historians estimate that the investments in New Edinburgh amounted to between a quarter and half of all the available money in the country.
In 1698 five ships set sail with twelve hundred colonists and a year’s food supply. They landed on the coast of Panama and started clearing forest to build the port of New Edinburgh. Just eight months later the ragged survivors (fewer than three hundred people) bolted for home. They reached Scotland just days after a second expedition of four ships and thirteen hundred people had left for Panama. Nine months later that second expedition also fled. Not a hundred people made it home. Lost with the dead was every penny invested in the venture.
Why did New Edinburgh fail? There were many reasons. Planning to trade with the local Indians, the colonists had stuffed their ships with Scotland’s finest products: woolen hose and blankets, ornamental wigs, and twenty-five thousand pairs of leather shoes. Alas, it proved difficult to sell warm socks and itchy blankets in the tropics. Meanwhile, hard tropical rains washed away the colonists’ supplies and their efforts to farm. To make matters worse, Spain, which had already established colonies in Central America and the nearby Caribbean islands, periodically attacked the new rivals.
The main causes of the disaster, however, were two mosquito-borne illnesses: malaria and yellow fever (along with dysentery, a disease not carried by mosquitoes). Records kept by the colonists report dozens of deaths each week. The first time Spain assaulted New Edinburgh, its soldiers found four hundred fresh graves. They had been filled by victims of diseases that had come to the Americas from Europe and Africa.
Back in Scotland, the calamity of New Edinburgh set off riots. Much of the country’s capital—that is, its cash available for investment—had been wiped out. At the time, England and Scotland were separate countries, although they shared a monarch. England, the bigger partner, had been pushing for a complete union for decades. Scots had resisted, fearing they would become a minor afterthought in an economy dominated by London. Now, as part of a union agreement, England promised to repay the people who had invested in New Edinburgh. The result was the formation of Great Britain—“with assistance from the fevers of Panama,” in the words of historian J. R. McNeill in his book Mosquito Empires.
LANDON CARTER HAD A PROSPEROUS VIRGINIA plantation about sixty miles north of Jamestown. He was a devoted father who agonized as malaria repeatedly struck his family in the summer and fall of 1757. Worst affected was his infant daughter, Sukey, who was racked by bouts of chills and fever. Landon recorded her struggle in a diary:
Dec. 7: Sukey looks badly all this evening with a quick Pulse.
Dec. 8: ’Tis her usual Period of attack which is now got to every Fortnight [two weeks]. . . . Seems brisk and talkt cheerfully. Her fever not higher.
Dec. 9: Continues better though very pale.
Dec. 10: Sukey a fever early and very sick at her stomach and head ach. This fever went off in the night.
Dec. 11: The Child no fever today but I thought her pulse a little quick at night.
Dec. 12: Sukey’s fever rose at 1 in the night. . . . This Child dangerous ill at 12, dead pale and blue. . . .
Dec. 13: Sukey’s fever kept wearing away Yesterday till one in the night when she was quite clear.
To live in Virginia, a heartbroken Carter wrote, “it is necessary that a man should be acquainted with affliction, and ’tis certainly nothing short of it to be confined a whole year in tending one’s sick children. Mine are now never well.”
Sukey died the following April, just short of her third birthday.
Malaria had impacts beyond the suffering of its victims. It was a historical force that deformed cultures, pushing societies to answer questions in ways that now seem cruel and wrong. Consider the seventeenth-century English investors who wanted to make money in North America. Chesapeake Bay had no silver or gold. The best way to make a profit was to produce something else to export to the home country. In New England, the Pilgrims depended on selling beaver fur. In Chesapeake Bay, the English settled on tobacco, for which there was a huge demand.
To satisfy the demand for tobacco, the colonists wanted to expand the plantation area. To do that, they would have to cut down huge trees with hand tools; break up soil under the hot sun; hoe, water, and tend the growing tobacco plants; cut the heavy, sticky leaves and drape them on racks to dry; and pack the dried leaves into barrels for shipping. All this would require a lot of labor. Where would the colonists get it?
They had two basic choices: indentured servants or slaves.
Indentured servants were contract laborers drawn from England’s throngs of unemployed people. Planters paid for the servants’ costly voyage across the Atlantic. The servants paid for their tickets by working for the planters for a set period of time, usually four to seven years. After that, indentured servants were free to claim their own land in the Americas—and, when they could afford it, to bring over indentured servants of their own.
Slavery is harder to define, because it has existed in many forms. Its key feature, though, is that the owner acquires the right to force slaves to work, and slaves never gain the right to leave. They must work and obey until they die or are freed by their owners. Indentured servants are members of society, although at a low level, and they have some rights under the law. Slaves are not usually considered members of society. In America, slavery took a harsher form than anything seen before in Europe, Asia, or Africa: chattel slavery, a brutal system in which slaves were regarded purely as property and had few rights, or none.
During the last quarter of the seventeenth century, the English colonists in North America chose slaves over servants. England became the world’s biggest slaver. This was a turnaround for a nation that had previously led Europe in opposing slavery. Although slavery had been common throughout Europe (including England) in medieval times, by the seventeenth century it had become rare in England. The decline of slavery was due partly to the fact that England was aswarm with unemployed laborers ready to do whatever work needed to be done. It was also due to English disgust and anger over the capture and enslavement of thousands of English people by Islamic pirates in North Africa. The English, in fact, were Europe’s least likely candidates to become slave masters.
Indeed, the English colonies had first turned to indentured servants. During the first century of colonization, between a third and half of the Europeans who arrived in North America were indentured servants. Slaves were rare at first in the English colonies—Virginia had only three hundred of them in 1650. Between 1680 and 1700, though, the number of slaves suddenly exploded. Virginia’s slave population rose in those years, from three thousand to more than sixteen thousand, and then kept rising. In the same period the number of indentured servants shrank dramatically. It was a turning point in world history, a time when English America became a slave society and England became the dominant player in the slave trade.
Why this turnaround? Historians and economists have offered various explanations.
One explanation starts with the English Civil War of the mid-seventeenth century. This disastrous conflict caused the country’s population to fall by almost 10 percent between 1650 and 1680. As a result, there were fewer English workers, which meant that their wages went up. This would have meant that Virginia planters had to pay higher prices to lure English indentured servants across the Atlantic. At the same time, indentured servants who had finished their years of labor in the American colonies were establishing new plantations and seeking their own indentured servants. Increased demand for servants also lifted the price.
This argument doesn’t explain why colonists chose African slaves as their alternative labor source. Planters could have found labor in Scotland and Ireland, where desperate poverty and the poor harvests of the Little Ice Age had driven many people to flee their homes. Gangs of Scottish refugees roamed the streets of London, begging for work and food. They would have been obvious candidates for labor in the colonies. Yet the colonists turned to captive Africans—people who did not speak the language of the colonists, had no wish to cooperate, and cost more to transport across the sea than indentured servants. Why?
The fate of New Edinburgh suggests one answer. The calamity of that colony showed that Scots and other Europeans died too fast in malarial areas to be useful as forced labor. Individual English and Scottish people and their families continued to make their way to the Americas, but businesspeople turned against the idea of sending over large groups of Europeans. Instead they looked for alternative sources of labor. Alas, they found them.
Indians were one obvious source of labor in the colonies. South of Virginia, the colony of Carolina was founded in 1670 as a business venture and settled by two hundred English colonists from the Caribbean island colony of Barbados. The colonists supplied themselves with Indian slaves, obtaining them from other Indians. Slavery occurred in most native societies in the Americas, but it took different forms from place to place. Among the Powhatan of the Chesapeake Bay, for example, slavery was usually a temporary state. Slaves were prisoners of war who were treated as servants until they were killed, ransomed back to their original groups, or introduced into Powhatan society as full members.
Among many Indian societies south of Chesapeake Bay, war captives also became slaves, but slavery there was more common and longer lasting. When foreigners appeared in Carolina, Indians there were more than willing to trade their extra captives for axes, knives, metal pots, and, above all, guns. There was a political dimension, too. The leaders of the Carolina colony asked nearby native groups to provide them with slaves by raiding the tribes who had sided with Spain and France, the colonial powers that were rivals of the English.
For its first four decades, Carolina was a slave exporter—the place from which captive Indians were sent to the Caribbean, Virginia, New York, and Massachusetts. Yet although the Indian slave trade was profitable, it was very short-lived. By 1715 it had almost vanished. In part, the Indian slave trade was a victim of its own success. As Carolina’s plantation owners requested more and more slave raids, the region became engulfed in warfare. Tribal groups that had suffered slave raids got hold of guns and attacked Carolina in a series of wars that the colony barely survived. Indian slaves who worked together in groups proved to be unreliable, even dangerous employees who used their knowledge of the land against their owners. Colonial records are full of accounts of the crimes committed by captive Indian laborers against their masters. Rhode Island and other northern colonies banned the import of the Indian slaves.
The worst problem, though, was disease. At first the English had praised Carolina’s healthful climate. Yet malaria arrived in Carolina, as it had in Virginia. The Carolina colonists decided to grow rice. Soon after came reports of chills and fevers—probably because the paddies or flooded fields used for growing rice are notorious mosquito havens. Malaria was followed a few years later by yellow fever. Cemeteries quickly filled. Unfortunately, Indians were just as prone to malaria as English indentured servants. In addition, they were more vulnerable to other new diseases, such as smallpox.
Native people died in ghastly numbers across the entire Southeast. Struck by disease and slave raids, the Chickasaw lost almost half their population between 1685 and 1715. Some groups vanished completely. The colonists looked for a different solution to their labor needs. They wanted a labor force that was not vulnerable to disease. English servants and Indian slaves were out. Whom else could they try?
Anyone who lives through a bout of malaria gains immunity to the disease, in the same way that children who survive a bout of chickenpox or measles become immune to those diseases. Yet acquired immunity to malaria is only partial. Both P. vivax and P. falciparum malaria occur in different strains, or varieties. People who survive a particular strain of P. vivax or P. falciparum malaria become immune only to that strain (or strains very similar to it). A different strain can lay them low. The only way to get widespread immunity to malaria is to get sick repeatedly with different strains.
Inherited immunity is different. Someone with inherited immunity is born with a genetic makeup that resists infection by malaria. Often they have small mutations that change the surface or shape of their red blood cells in ways that block malaria parasites from climbing inside the cells. Inherited malaria resistance occurs in many parts of the world, but the peoples of West and Central Africa have more of it than anyone else. They are almost completely immune to P. vivax malaria and also have considerable resistance to P. falciparum. In addition, many people in those regions are repeatedly exposed to malaria during childhood. Survivors possess both types of immunity, inherited and acquired. When the English colonists in North America were struggling to meet their labor needs, adults in West and Central Africa were less vulnerable to malaria than anyone else on earth—as they still are.
Almost all the slaves ferried to the Americas came from West and Central Africa. P. vivax malaria could have come to North America with colonists from England, but P. falciparum never thrived in England. It almost certainly came to North America inside the bodies of African slaves. Yet with their inherited and acquired immunity, Africans were more likely to survive and produce children than the English colonists in malaria-ridden Virginia and Carolina. Biologically speaking, the Africans were fitter, which is another way of saying that, in those places, they were genetically superior. Rather than gaining an edge from this superiority, however, Africans saw their biological advantage turned against them. Their immunity became a reason for their enslavement.
Exact figures and causes for European and African deaths in the colonies are hard to pin down. Overall, though, it appears that in zones where P. falciparum malaria and yellow fever occurred, the English were between three and ten times more likely to die during their first year in America than Africans were. For European colonists, the economic logic was hard to ignore. If they wanted to grow tobacco, rice, or sugar, they were better off using African slaves than European indentured servants or Indian slaves.
Slavery and P. falciparum thrived together. Consider the border between the states Pennsylvania and Maryland. Surveyed by Charles Mason and Jeremiah Dixon in 1768, this border became known as the Mason-Dixon Line. As a cultural boundary between North and South, between Yankee and Dixie, the Mason-Dixon Line marks one of the most lasting divisions in American culture. It roughly split the East Coast into two zones. South of the Mason-Dixon Line, P. falciparum was an endemic threat. North of the line, it was not, because temperatures were too cool for it to survive. South of the line, African slavery became a dominant institution. North of the line, it did not.
Malaria did not cause slavery, but it strengthened the economic case for it. Tobacco planters did not plot to take advantage of Africans’ immunity to malaria. In fact, there is little evidence that the first slave owners understood malaria resistance, partly because they did not know what the disease really was and partly because people in isolated plantations could not easily make overall comparisons. Regardless of what they understood, though, planters who imported slaves tended to have an economic edge over planters who imported indentured servants. The slaves were more likely to survive and work for their owners. The indentured servants were more likely to die and be an economic loss. Successful planters imported more slaves, and newcomers copied the practices of their more successful neighbors. The slave trade took off.
Slavery would have existed in the Americas without the malaria parasite. In 1641, Massachusetts, which had little malaria, became the first colony to pass a law legalizing slavery. A century later, during the middle of the eighteenth century, the healthiest spot in English North America might have been the Connecticut River Valley in western Massachusetts. Malaria was almost nonexistent there. Infectious disease was extremely rare by the standards of the time. Yet slavery was part of the furniture of daily life. Almost every minister, usually the most important man in town, had one or two slaves. In Deerfield, one of the biggest villages in the valley, 8 percent of the people along the main street were slaves.
Far to the south, on the other side of the tropical malaria belt, was Argentina, which started as a Spanish colony in South America. With few mosquitoes and cool weather, Argentina had little malaria. Yet, like Massachusetts, it had African slaves. Between 1536, when Spain founded its first settlement in Argentina, and 1853, when Argentina abolished slavery, between 220,000 and 330,000 Africans landed in Buenos Aires, the main port and capital of Argentina.
North of Argentina was Brazil, which had been colonized by Portugal. It was closer to the equator and therefore warmer. Mosquitoes and malaria both thrived in Brazil. So did slavery. Many more slaves arrived there than in Argentina, as many as 2.2 million. By the 1760s and 1770s, about half the people in both Brazil and Argentina were of African descent. In spite of this similarity, the impact of slavery in the two countries was completely different. Slavery was never vital to colonial Argentina’s most important industries, such as cattle ranching. Colonial Brazil, in contrast, could not have functioned without slaves, which were essential to its most important industry: sugar. Argentina was a society with slaves. Brazil was culturally and economically defined by slavery.
All American colonies had slaves. Yet the colonies to which the Columbian Exchange brought P. falciparum malaria ended up with more slaves. They became slave societies in ways that other colonies did not.
In the 1640s a few Dutch refugees from Brazil landed on Barbados, the easternmost Caribbean island. Unlike the rest of the Caribbean, Barbados never had a large Indian population. English colonists had moved in hoping to cash in on the tobacco boom. When the Dutch arrived, the island had about six thousand inhabitants, including two thousand indentured servants and two hundred slaves.
Tobacco turned out not to grow particularly well on Barbados—but there was an alternative. The Dutch refugees had learned in Brazil how to plant sugarcane, and they shared this knowledge with the English colonists on Barbados. Sugar was in demand to satisfy Europe’s sweet tooth, and Barbados proved to be good sugarcane territory. Production of sugar rapidly grew.
Sugar production was hard work that required many hands. Sugarcane is a tall, tough Asian grass, somewhat like its cousin bamboo. Plantations burned the crop before harvesting it to prevent the knifelike leaves from slashing workers. Swinging long knives into the hard, soot-smeared cane under the tropical sun, field hands quickly spattered themselves with a sticky mixture of dust, ash, and cane juice. The cut stalks were crushed in a mill to squeeze out their juice, which was boiled down in great kettles enveloped in smoke and steam. Workers ladled the hot syrup into clay pots. As the syrup cooled, crystals of pure sugar formed. What remained in liquid form was molasses. Most of the molasses was used to produce the alcoholic drink rum, which required feeding yet another fire under another infernal cauldron.
Where would the Barbados cane planters get the labor they needed? In Virginia, slaves cost twice as much as indentured servants, if not more. Yet the Dutch West India Company, a badly run outfit that was desperate for cash, was willing to sell Africans cheaply in Barbados. Slaves and servants there were roughly the same price. The island’s new sugar barons imported servants and slaves by the thousands: beggars and the unemployed from England, luckless captives from wars in Africa. Covered in sweat and gummy cane soot, Europeans and Africans wielded their knives side by side in the cane fields.
Then the Columbian Exchange raised the cost of indentured servants.
Hidden on the slave ships was a stowaway from Africa: the mosquito Aedes aegypti. Inside its gut it carried its own hidden stowaway, the virus that causes yellow fever, a disease that originated in Africa. The yellow fever virus spends most of its life cycle inside the mosquito. It uses human beings only to pass from one insect to the next. Typically it remains in a human host less than two weeks. During this time it drills into huge numbers of cells and hijacks their genetic material to make billions of copies of itself. These flood the bloodstream. Biting mosquitoes pick them up and pass them to new hosts.
The cellular invasion of yellow fever usually has little effect on children. Adults, though, are hit by massive internal bleeding. Blood collects and thickens in the stomach. Sufferers vomit up the black blood—the chief symptom of yellow fever. Another symptom is jaundice, or a yellowing of the skin, which gave rise to the disease’s nickname of yellow jack. (A “Yellow Jack” was a flag flown by ships that were quarantined, or unable to land, because of disease on board.) The virus kills about half its adult victims. Survivors acquire lifelong immunity. In Africa, yellow fever was a childhood disease that caused relatively little suffering and made many people immune. In the Caribbean, it was a dire plague that passed over Africans while ravaging Europeans, Indians, and black slaves who had been born on the islands.
The initial yellow fever onslaught began in 1647 and lasted five years. It hit first in Barbados. Terror spread as far away as Massachusetts, which quarantined incoming ships for the first time. One record from the period says that six thousand people died on Barbados alone. Almost all the victims were Europeans—a searing blow for the island’s colonists. A modern researcher estimates that the epidemic may have killed 20 to 50 percent of the people living in the Caribbean, Central America, and Florida. Most of the victims were European or Indian.
The epidemic didn’t wipe out the sugar industry. Sugar was too profitable. Barbados, an island of just 166 square miles, was already making more money than the rest of English North America. Sugar had spread to other Caribbean islands, and slave labor along with it.
The new diseases also spread through the warm regions of the Americas. Malaria traveled from the Caribbean to South America, then up the Amazon River, where there were many Anopheles mosquito species available to carry the parasite. The first Europeans to visit Amazonia described it as a thriving, healthful place. That was before malaria—and, later, yellow fever—turned many of the region’s rivers into death traps. By 1782, malaria was sabotaging European expeditions in the upper reaches of the river basin.
The effects of disease were even worse in the northeastern bulge of South America, a region that geographer Susanna Hecht has called the Caribbean Amazon. Bounded to the south by the Amazon River in Brazil and to the west by the Orinoco River in Venezuela, this region was a watery place that the native Arawak and Carib people controlled with sprawling networks of dikes, dams, and canals. They managed large areas of forest for tree crops, especially the palms that in tropical places provide fruit, oil, starch, wine, and building material.
This landscape of gardens, orchards, and waterways served for centuries as a gateway between the islands of the Caribbean and the interior of South America. By the eighteenth century, however, diseases brought by the Columbian Exchange had weakened the local people. Smallpox, influenza, and tuberculosis cleared the way for malaria and then yellow fever. Indians retreated into the interior. Europeans seized the coast, creating sugar plantations.
Part of the coast became the French colony of Guyane (now known as French Guiana), site of the notorious prison called Devil’s Island. As many as eighty thousand Frenchmen were sent to Guyane in the nineteenth and early twentieth centuries, either to Devil’s Island or to labor in chain gangs on plantations on the mainland. Very, very few of them returned to France. Malaria either killed prisoners or weakened them so that they fell victim to other ailments. Disease claimed so many that Guyane became known as a “dry guillotine.” The guillotine, an execution machine invented in France, chopped off victims’ heads with a sharp, sliding blade. Malaria was a blade that killed without needing to wet itself with blood.
WITH THE SUCCESS OF SUGAR PLANTING IN Barbados, colonists from England, France, the Netherlands, Portugal, and Spain began clearing neighboring Caribbean islands as fast as possible, planting cane in the flatlands and cutting trees on the hills for fuel. With the trees gone, the soil began to erode. Rainfall, no longer absorbed by forests, washed soil down the slopes and formed coastal marshes. In the not-too-distant future, workers would be ordered to carry the soil in baskets back up the slopes in an attempt to reverse the damage.
Even the worst ecological mismanagement benefits some species. One of the winners in the Caribbean was Anopheles albimanus, a mosquito species that became the region’s chief carrier of malaria. This mosquito likes to breed in coastal, algae-covered marshes. Deforestation and erosion are its friends. It can reproduce in huge numbers when conditions are right.
From the point of view of A. albimanus, the arrival of Europeans in the Caribbean was the start of a golden age. The Europeans created new coastal marshes where the mosquito population soared. The species gradually grew accustomed to hosting the P. vivax malaria parasite, and it spread P. vivax from the Caribbean to Mexico. P. falciparum did not arrive until much later, partly because the mosquito was more resistant to it.
The mosquito that carries yellow fever, Aedes aegypti, also benefited from human activity in the Caribbean. It likes to breed in small amounts of water, near human beings.
Sugar mills in the Caribbean during the seventeenth and eighteenth centuries abounded with excellent breeding places: the crude clay pots into which boiled cane juice was poured to form sugar crystals. These pots would have been full of sugary material, food for the bacteria that mosquito larvae eat. Sugar plantations were like factories for producing yellow fever.
The Europeans who came to the islands did not know these biological details. However, they did know that the Caribbean was, as one historian of malaria put it, “a lethal environment” for anyone who was not immune to malaria and yellow fever. That gave Africans, many of whom were immune to those diseases, an advantage—one that helped doom them to slavery.
Disease has shaped history in many ways. One example is the role played by the malaria parasite in the birth of the United States.
In May of 1778, with the Revolutionary War in full swing, Henry Clinton became commander in chief of the British forces in the rebellious American colonies. The British believed that the Carolinas and Georgia were full of loyalists—that is, colonists who remained loyal to Great Britain. Based partly on inaccurate reports from loyalists who had fled to London, British leaders thought that these southern loyalists existed in large numbers but were afraid to declare their support of the home country. Clinton decided upon a “southern strategy”: he would send a force south to hold the region long enough for the silent loyalist majority to declare its support for the British king.
Although Clinton didn’t know it, he was leading an invasion of the malaria zone.
British troops were not seasoned—they had not endured and survived malaria attacks. Two-thirds of them were from malaria-free Scotland. The British soldiers who had served a year or two in the colonies had done so mostly in New York and New England, north of the malaria zone. By contrast, the southern colonists were seasoned. Almost all were immune to P. vivax, and many had survived P. falciparum.
British troops successfully besieged Charleston, South Carolina, in 1780. A month later Clinton left for the North, instructing his troops to chase the Americans into the backcountry. He put Major General Charles Cornwallis in charge of this mission. Cornwallis marched inland in June, the prime season for the Anopheles mosquito. By autumn, he complained, disease had “nearly ruined” his army. So many men were sick that the British could barely fight. Loyalist troops from the colonies were the only men able to march. Cornwallis himself lay ill while his men lost the Battle of King’s Mountain. In the words of malaria historian J. R. McNeill, “Cornwallis’s army simply melted away.”
Beaten back by disease, Cornwallis abandoned the Carolinas and marched to Chesapeake Bay, where he planned to join another British force. He arrived in June 1781. Clinton ordered him to take a position on the coast so that the army could be carried by ship to New York if necessary. Cornwallis protested that Chesapeake Bay was notoriously disease-ridden. It didn’t matter. He had to be on the coast if he was to be useful. So his army marched to Yorktown, fifteen miles from Jamestown, and camped between two marshes, near some rice fields. Cornwallis bitterly described the location as “some acres of an unhealthy swamp.”
To his horror and surprise, a French fleet appeared off Chesapeake Bay, ending the possibility of escape by sea and trapping the British. Meanwhile, General George Washington marched his Revolutionary Army south from New York. By this time the American Revolution was so short of money and supplies that Washington’s men had mutinied twice—but an opportunity had arisen. The British army was unable to move and was stricken by disease. Cornwallis later estimated that only 3,800 of his 7,700 men were fit to fight.
The bravery and skill of the revolution’s leaders contributed to the victory of the American colonists over the British. Yet what McNeill called “revolutionary mosquitoes” played an equally vital role. With Cornwallis’s troops falling in ever-greater numbers to the diseases of the Columbian Exchange, the British army surrendered on October 17, 1781, and the United States was born.
