Pathogenesis: A History of the World in Eight Plagues

by Jonathan Kennedy

The French defeat at the hands of the Haitian rebels—and the island’s mosquitoes—helped to shape the modern world. Without a base in Saint-Domingue, Napoleon had little choice but to abandon his grand plan of building an empire in the western hemisphere. In December 1803, France sold its North American colonial possessions to the United States for $15 million.

This demonstrated just how vulnerable white plantation owners in the Caribbean were: they were not just massively outnumbered by an angry enslaved population but also faced an invisible enemy that struck down forces sent from Europe to save them.

It isn’t a coincidence that Britain banned the Atlantic slave trade in 1807, three years after Haiti declared independence. At the time, this move wasn’t seen as a first step toward the abolition of slavery; rather it was an attempt to preserve the institution.[81] The British hoped that banning the trade in human beings would cut off the cheap supply of African labor and force plantation owners to take better care of “their property,” therefore reducing the risk of rebellions spreading from Haiti to other colonies in the region. This strategy failed. There were uprisings in Barbados in 1816, Demerara (today’s Guyana) in 1823, and then Jamaica in 1831–32. Even though the Caribbean slave plantations remained hugely profitable, and an increasingly important part of the British Empire’s economy, the government in London decided to abolish slavery altogether in 1833.

Enslaved Africans played a crucial role in winning their own freedom by making the risk of another Haiti too much for the British government to bear.

The Haitian Revolution increased North American plantation owners’ fears that slavery could be abolished there too—as the French revolutionary government had done in 1793.[84] This anxiety influenced their excessive response to the threat posed by the anti-slavery movement in the north, which in turn contributed to the polarization that was already cleaving the country apart.

Support for what was then the pro-slavery Democratic Party in the 1860 presidential election was strongest in counties that had the highest rates of malaria—presumably because African American slave labor and the racist ideology that justified it were most strongly entrenched in these disease-riddled areas.

The Union Army was bigger and better supplied, but it struggled to win battles. The reasons for this include incompetent leadership, brave adversaries and logistical problems. Another important factor was that most of the Northern soldiers had not developed immunity to malaria, whereas most of the Southern soldiers had. According to one estimate, 40 percent of Union soldiers fell ill each year with the disease. The debilitating fevers were massively disruptive to the war effort and, if they didn’t kill sufferers outright, made them susceptible to other infectious diseases such as dysentery and measles. Throughout the Civil War, twice as many Northern troops died from disease as were killed in battle by Confederate guns.

Malaria didn’t change the outcome of the Civil War: the North won despite the disproportionate toll that Plasmodium falciparum had on the Union Army. But it probably delayed victory by months or even years, which in turn had a momentous effect on the postwar settlement.

At the outset of the conflict in spring 1861, Lincoln was trying to maintain a fragile war coalition that included not only his fellow Republicans but also Northern Democrats and Unionists in border slave states that hadn’t seceded. His objectives were therefore relatively modest: to keep the South in the union and restrict the expansion of slavery. He realized that promising to abolish slavery would have ripped this alliance apart. But by the summer of 1862, as the North’s war effort continued to struggle, Lincoln was willing to consider more radical measures. He came round to the idea that abolishing slavery could break the deadlock. African American slave laborers were, after all, a crucial part of the Southern economy and also played a big role in providing logistical support to the Confederate Army. They were, according to Lincoln, “undeniably an element of strength to those who had their service, and we must decide whether that element should be with us or against us.”[89] On 22 September he concluded that abolishing slavery had become “a military necessity, absolutely essential to the preservation of the Union.” Then, 100 days later on New Year’s Day 1863, the Emancipation Proclamation declared “that all persons held as slaves…are, and henceforward shall be free.”

A greater revolution for humanity than the theories of Copernicus, Darwin, and Freud put together came with the invention of the toilet. —Goce Smilevski

For many Britons, the fact that the Industrial Revolution occurred first in their country is a source of national pride; they see industrialization as the natural consequence of their innate superiority, specifically their pre-eminence in science and engineering. Yet this jingoistic explanation doesn’t make sense, because the technical knowledge that made innovations in the British textile sector possible existed throughout Europe, and had done so for several generations.[2] Why, then, was the United Kingdom the first country in the world to go through the process of industrialization? It certainly helped that Britain had large and easily accessible coal deposits that were already being used for domestic fuel, as Britons had cut down most of their woods and forests over the previous centuries to make way for agricultural land and to use in shipbuilding. It was also critical that wages in Britain were markedly higher than in the rest of Europe—as a result of the post–Black Death transition from feudalism to agricultural capitalism. Consequently, investment in steam-driven machinery to reduce reliance on the workforce made much more economic sense in Britain than in parts of the continent where coal was scarce and expensive, and labor plentiful and cheap. The legacy of previous infectious disease outbreaks catalyzed the Industrial Revolution in a number of other ways too.

Furthermore, a large proportion of the vast profits from colonialism and slavery were reinvested in Britain. In this way, the suffering of enslaved Africans and colonized peoples paid for the construction of vital infrastructure such as the roads, canals, docks and railways that made the Industrial Revolution possible.

Because the marked increases in wealth and health occurred at roughly the same time, it is widely believed that economic growth led automatically to improved human welfare. This is the crux of the theory that as countries get richer they pass through an “epidemiological transition” in which life expectancy improves as fewer people die young from infectious diseases, and more people are killed at an older age from chronic diseases such as cardiovascular disease and cancer.[15] In fact, the reality is much more complex and troubling.

The new provincial towns and cities really dragged down the national life-expectancy figures. They were not only considerably lower than the figure for England and Wales, they also fell markedly in the second quarter of the nineteenth century.[18] The numbers are skewed by very high infant mortality rates, with one in five babies dying before their first birthday.[19] In the central areas of Manchester and Liverpool, you could expect to live for around twenty-five years—a shorter lifespan than at any time since the Black Death.[20] The figures are even worse when we focus just on the poor. Life expectancy for factory laborers was seventeen in Manchester and fifteen in Liverpool.[21] Death rates were so high among the urban working classes that the population was only able to sustain itself because of the continual inflow of people from the surrounding countryside, and increasingly from Ireland. As northern towns and cities were the epicenter of the Industrial Revolution, this is clear evidence that economic growth and increasing real wages did not automatically lead to improvements in health via the invisible hand of the market.

To provide some relief from the misery of their situation people drank, and among the urban poor alcoholism was widespread. The quickest way to get out of Manchester was by the bottle, as a popular saying went.

Anyone who could afford it would live outside the slums, often to the west—and therefore upwind—of the industrial center. This pattern of urban segregation is still apparent in many European cities today, including London and Paris.

The crowded and unsanitary conditions in working-class urban districts created new habitats in which previously uncommon pathogens thrived.

But there’s a twist: as the pathogens die, they release an incredibly powerful toxin that causes the plasma—the transparent liquid component of our blood—to drain into the intestines. From there, it is expelled from the body through explosive diarrhea and projectile vomiting. In severe cases, victims can lose a quarter of the body’s fluid within a few hours. Severe dehydration makes sufferers appear shriveled. Ruptured capillaries turn the skin black and blue. Within a few days of the onset of symptoms, a little more than half of victims would have been dead.

Cholera first arrived in the UK in 1831, just as the Industrial Revolution was transforming Britain’s economy and society. With their poor hygiene and unsanitary water supplies, the working-class districts of towns and cities provided a perfect environment for the bacteria to spread. As Evans points out, “these conditions might almost have been designed for it.”

Many people looked at all these facts—the symptoms, the sudden appearance of outsiders, the disproportionate burden on the lower classes—and surmised that cholera wasn’t a previously unknown disease at all, but a plot by the authorities to poison the urban poor.

As Evans points out, this “rekindled long-held popular resentments against the anatomists, and the cholera epidemic was widely held to be another example of the same business.” So when the crowds attacked doctors as they tried to transport suspected cholera victims to hospitals for isolation, it was because they genuinely feared that patients were going to be killed and their bodies used for medical research.

It was not only popular among the recipients, who believed it was their birthright to receive help from more fortunate members of the community when times were hard. It was also supported by the landowning elite, who bore most of the cost and who saw it as a way of conserving the status quo amid growing calls for equality and the revolutionary chaos then engulfing France.

By the early 1830s, the government could no longer resist demands to broaden participation in politics.[38] Some historians have argued that this was the only point in modern British history when revolution was a distinct possibility.

They believed that the old system of welfare handouts encouraged dependence and indolence, which in turn created more poverty. The stipulation that poor relief could only be accessed in one’s native parish was seen as an unnecessary restriction on the free movement of labor. The New Poor Law aimed to distinguish the “deserving” poor—the sick and elderly—from what its authors saw as scroungers, by making welfare support so disagreeable for able-bodied people that they would ask for help only in the most desperate circumstances.

To access support, families had to enter the workhouse.

Charles Dickens, in Oliver Twist, suggested that the poor now had the option of starving slowly in the workhouse or quickly at home.

Chadwick realized that the poor health of the working population undermined factories’ productivity and created a drag on the economy.[43] After 1834, he became a leading light in what became known as the sanitary movement, arguing that the health of the urban poor could only be improved by cleaning up towns and cities and constructing sewerage and water infrastructure.

cholera was “the best of all sanitary reformers.”

It was not lack of technology or money that stopped society from dealing with the deadly unsanitary conditions in working-class neighborhoods of provincial towns and cities; rather, it was the absence of political will. Providing sanitation and clean water to the masses is an enormously expensive undertaking, but one that delivers huge long-term economic and non-economic benefits. Such projects are not viable for private companies motivated by short-term returns on investment, so the problem of sanitation can’t be solved by the invisible hand of the market. Instead, it is imperative that the state steps in, at the very least to coordinate.

Proponents of the “civic gospel” argued that the deprivation, disease and death that blighted industrial towns and cities was a moral abomination and that their wealthy congregations had a duty to improve the lives of the urban working classes.

The examples of Hamburg—as well as the provincial towns and cities of the UK fifty years earlier—demonstrate that economic growth alone does not guarantee the health and well-being of the population. Clearly, the combined actions of self-interested individuals are not capable of delivering broad-based development. John Maynard Keynes is supposed to have said that such an idea assumes that “the nastiest of men for the nastiest of motives will somehow work for the benefit of all.”

Research from Burundi demonstrates that each time a child gets sick with diarrhea, the average cost to a family, in terms of health care and lost earnings, is $109—almost twice the average monthly salary.

The American economist Jeffrey Sachs and his colleagues have demonstrated that malaria has a deleterious impact on economic growth, with countries that are not afflicted by malaria enjoying five times the GDP per capita of those that are.

Sachs and his collaborators argue that infectious diseases create a “poverty trap” that is almost impossible to escape.

“To administer medicines to diseases which have already developed…is comparable to the behavior of those persons who begin to dig a well after they have become thirsty.”

In the West we celebrate Edward Jenner as the pioneer of vaccines, but the Chinese have been inoculating their population against smallpox for over 1,000 years.

The health transformation in the first thirty years of the People’s Republic of China occurred even though China was very poor and only achieved moderate economic growth rates.

The improvements in Chinese longevity between 1949 and 1980 were almost entirely the result of a reduction in infectious diseases.

China vaccinated almost all its 600 million inhabitants against smallpox; its last outbreak was in 1960, two decades before it was eradicated globally.

In 1958, the state urged the population to “exterminate the four pests,” which were rats, flies, mosquitoes and sparrows—the latter because they were accused by the Chinese Communist Party of being capitalist birds due to their penchant for “stealing” large amounts of grain and fruit from hard-working peasants.

It was the rural interior that suffered the most, in large part because the economic reforms abolished agricultural communes and with them the free, decentralized, barefoot-doctor-led health care and public health system.

My intention here isn’t to advocate communism. Rather it’s to demonstrate that, just as the state was crucial in defeating infectious diseases in late-nineteenth-century Britain, it was also vitally important in China’s escape from the poverty trap in the late twentieth century. Yet we must not overlook the massive downsides to the Chinese model of development. The improvements in health and wealth have been achieved despite an Orwellian disregard for individual freedom and human rights—from the Great Leap Forward to the present-day treatment of the Uighurs, and of course the response to Covid-19. Notwithstanding, it was the iron fist of the totalitarian state that pulled China out of the poverty trap rather than the invisible hand of the market.

The paralysis in much of sub-Saharan Africa is, in part at least, a legacy of colonialism.

Acemoglu argues that the character of the colonial state survived independence and continues to influence the development trajectory of former colonies. Accordingly, many sub-Saharan states lack the ability or willingness to plan and implement the kind of public health measures necessary to prevent the spread of infectious diseases—such as investing in basic water, sanitation and health systems.

We shouldn’t, however, be too fatalistic about the destiny of postcolonial Africa.

The conference agreed that investment in health facilities and drugs would not be enough to improve health in poor countries. Rather, the Alma-Ata Declaration argued that fundamental political and economic reform—in terms of tackling iniquitous power relations between former colonies and their colonizers, and mobilizing communities to take an interest in health care—was essential to achieving its goal.

Unfortunately, the optimism of Alma-Ata was quickly undermined by high-income countries—most notably the U.S. and the UK, where the arrival of Ronald Reagan and Margaret Thatcher on the scene in the late 1970s and early 1980s marked a fundamental shift in political consensus. Their new economic orthodoxy harked back to the laissez-faire approach of the previous century. In this new environment, “Health for All” was deemed too radical and too political. The focus shifted to taking out infectious diseases one by one using medicines and technology, without tackling the poverty and powerlessness that are the underlying causes of ill health. The U.S. and its allies reduced their funding to the WHO. Instead they funneled money for global health projects into organizations like the World Bank, which gave them more control because member states’ voting power is proportional to their financial contribution.

In China and other parts of East Asia, by contrast, where governments avoided following the World Bank and IMF’s free-market diktats and the state played a central role in development, the economies boomed.

Structural adjustment had a profoundly negative impact on public health. Governments were forced to cut social welfare budgets, including those for public health and health care. Recipient countries were often required to cap the public-sector wage bill, resulting in the emigration of large numbers of doctors and nurses to high-income countries. In the 1980s, the number of doctors in Ghana fell by half, and only one-sixth of Senegal’s nurses remained, compared to the start of the decade.[46] Structural adjustment programs frequently introduced user fees for health care that mimicked the U.S. model. As a result, the poor were unable to access even the most basic care. For example, when the World Bank forced Kenya to impose a charge of thirty-three cents to see a doctor, patient visits fell by half.[47] (The number of patients almost doubled when the fee was suspended.) And it has been shown that structural adjustment caused an increase in some infectious diseases, including TB.

low-income countries, predominately in sub-Saharan Africa, have been denied the opportunity to follow a similar strategy; in effect, high-income countries “kicked away the ladder” that they had used to climb out of the poverty trap. Instead, sub-Saharan African countries were encouraged to use an untested approach to public health that stressed medicine and technology.[49] But states in low-income countries weren’t able to take full advantage of the exciting new possibilities offered by advances in medical science. How could they, after being hollowed out first by colonialism and then by structural adjustment?