Episode 17 — Venice and the plague – part 1

Intro

In 1348 — or maybe late in 1347 — a ship arrived in Venice with an unexpected — and unwanted — cargo.

From the Black Sea, besides the normal goods of hemp, fur, cotton and silk, it brought the plague to Venice.

From Venice, the plague moved onwards to all of Western Europe.

Millions died in what was probably one of the largest disasters ever to hit the continent.

Links

• The Black Plague
• A Chronology of the Black Plague in Venice
• Bad air will get you sick
• The Venetian Lazzaretti

Transcript

Episode 17 — Venice and the plague – part 1

Besides my history walks in Venice, I also work as a guide on an island in the Venetian lagoon, called the Lazzaretto Nuovo.

That island was one of the first lazzaretti in the world, and an important element in how the Republic of Venice learned how to govern the plague.

This episode contains some of the general information I tell people on the guided visits to the museum on the Lazzaretto Nuovo.

It is meant as an introduction to the plague in Venice and Europe. In the next episode, I’ll explore more in-depth how the Republic of Venice responded to the emergency, and after that, I might do an episode on the mythical plague doctor.

What happened initially?

So, how did all this misery start?

Venice — in fierce competition with Genoa — had over many centuries developed an extensive trade network, which spanned all the Mediterranean and the Black Sea.

The city was one of the main entry points of luxury goods into Western Europe, and that trade had made Venice one of the riches cities in the world.

The Venetian merchant ships were the backbone of Venetian wealth, power and status.

Now these same ships also brought the plague to Venice, and to Europe.

The first wave

Venice was — in the early Middle Ages — one of the most populous cities in Europe.

With a population of between a hundred and a hundred and fifty thousands, only Constantinople and Thessalonica were larger, and Kyiv and Naples equals.

In the 1300s, Venice was still in the top ten of European cities.

As the plague burned through the city in 1348, tens of thousands died. That was enormous for a medieval city, even for a large one like Venice.

People died faster than they could be buried, and soon all attempts at giving the victims proper burials were abandoned.

Corpses lay piled up on the canal sides, while the boats, which should take them away, were either without rowers, or still out in the lagoon, full of cadavers, as the workers who should unload the dead in the pits in the mud, were either dead themselves, sick or had fled.

Unlike famine, the plague killed rich and poor alike, and made no difference between the young or the old, men or women, the devout or the epicureans, the innocent or the sinners.

We cannot know how many people died in Venice during the first wave of the black plague, but it could be ten, twenty, thirty percent of the entire population, or even more.

In the 1630 epidemic in Verona — where we have more reliable numbers — the population was fifty-four thousands before the epidemic, which dropped to twenty-two thousands after. Some might have fled, but the vast majority of the missing sixty percent were likely dead.

Losing maybe a quarter or a third of the population in a short period had profound consequences on society.

Economically, it led to a shortage of labour, demands for higher wages, and consequently inflation.

Knowledge was lost.

Most acquired knowledge and experience were kept in people’s heads, and transmitted orally from one generation to the next. When many people died, their experience and knowledge died with them.

Imagine a Venetian ship arriving in a foreign port, but those who had been there before, had all died during the journey. How do the survivors find their way around, connect to other people, so they can sell their merchandise and acquire goods, which can be sold for a profit back in Venice?

Something as basic as domestic supply lines, like from farmer, to miller, merchant, baker, and consumer, could break if too many people died. The chain was built of people knowing each other personally, so if many people died, it could fall apart, causing all sorts of secondary problems besides the epidemic itself.

The official, orthodox explanation of the plague was that it was God’s punishment for the sinfulness of people, and the answer was therefore repentance and prayers. However, the plague killed the newborn, unmarried women, nuns and people of the church in equal measures.

Consequently, the times saw both more religious fervour, and a loss of credibility of the church and the institutions.

Psychologically, the plague, the fear, the anguish, the suffering and all the deaths must have had a devastating impact on the survivors, who all feared that they would be next.

Further waves

Despite the grimness of the situation, after a couple of years the plague seemed to be over.

Except it wasn’t.

The plague came back to Venice in 1361, in 1371, in 1374 and again in 1390, each time equally devastating.

And as before, the virulence of the disease meant it wasn’t just Venice, but all of Europe.

Around the year 1400, Venice — and Europe in general — had lost approximately half their population.

One in two Europeans had died of the plague in half a century, in a series of cataclysmic epidemics which killed people completely at random.

To put it into perspective, Western Europe currently has a population of around half a billion, that is, five hundred millions.

Now imagine that a series of inexplicable events, roughly every ten years, against which we had no effective response, killed 250 millions in fifty years.

How many of us survivors wouldn’t have lost somebody close? How many of us wouldn’t have seen a loved one die in front of our eyes?

On a purely practical level, how would we dispose of the dead? Even, who would dispose of the dead, when there were so few left, and they’re so traumatised.

How would our societies function, in front of such a loss of life? Who would perform all the essential functions our societies rely on? Would anybody trust the authorities and the institutions any more?

How could we remain living and feeling human beings, faced with such a catastrophe?

And yet, if we’re alive, we must live and love. We must move on, rebuild, recover, form new bonds, living with the pain and loss, and never knowing if the darn thing comes back to get you too.

During the 1900s, the Spanish Flu killed probably tens of millions in Europe, and so did both of the world wars. That was bad. We still live in the shadow of those events, and yet it was but a fraction of what our ancestors lived through six centuries ago.

It only seems smaller to us because we see from a very long distance.

What is the plague

What was this disease which did all this to our forefathers and fore-mothers.

The plague is a bacterium, which has been named yersinia pestis after Alexandre Yersin, who identified it in 1894.

Yersinia pestis can infect us in various ways.

The most common case is an infection through the blood, by a scratch or an insect bite.

In this case, the infection concentrates in the lymph nodes under the armpits, on the neck, and in the groin. The lymph nodes swell up, and can reach the size of an egg. It is supposedly rather painful.

Most people with such an infection will likely have a very high fever.

If the immune system can defeat the infection, this is as far as the disease gets. The infection recedes, the lymph nodes return to their normal size, and the person recovers.

In the less fortunate case, the immune system cannot defeat the infection, which then returns into the blood stream, spreads throughout the entire body, and causes sepsis. If the disease itself doesn’t kill the person, their immune system will. With the infection present everywhere in the body, the immune system can go into overdrive, and kill cells at random, failing to distinguish between which cells constitute the person, and which the infection.

This final phase is characterised by necrosis of the body extremities. The fingers and toes, and sometimes also the nose and the lips, go black as the cells die.

Death usually follows shortly after.

The case fatality rate is around forty to fifty percent for infections of yersinia pestis though the blood, but it can be higher for particularly virulent strains of the bacteria.

It is also possible to get the infection through the lungs — pneumonic plague.

An infection via the lungs happens through droplets in the air. Another afflicted individual, whose infection has spread to the lungs, can emit such droplets by coughing or sneezing.

Pneumonic plague is very fast, and almost always fatal, even with modern medicine.

It is also possible to get infected by the plague by eating the raw meat of infected animals, in particular rodents.

However, in the normal case, a bit more than half the infected can be expected to survive.

The incubation period of the plague is around one week, and the disease kills in two to seven days after the first visible symptoms, depending on the strain of the bacteria.

The doctors of the time referred to the swollen lymph nodes as tumours or buboni, which is the origin of the term Bubonic Plague.

The black fingers and toes in the final phase of the disease led to the name Black Plague.

The two names therefore refer to the same disease, but to two different phases of the infection.

Epidemics

Historically, the plague has caused three major pandemics.

The first was the Justinian Plague, from the mid-500s into the 700s, in the Byzantine Empire, in Italy and elsewhere in Africa and Asia. This plague was one of the many factors leading to a diminished Byzantine presence in Italy, and therefore towards Venice as an independent polity.

The second pandemic was the Medieval black plague, from the 1340s into the 1700s, which is our subject.

The third and last plague pandemic was in the late 1800s, centred mostly on China, South-east Asia and Africa.

Immunity and vaccines

Can you get the plague twice? Can you acquire immunity?

Unfortunately, the answers are yes and no, respectively.

I’m not a doctor, and finding reliable information about the plague online is not easy. It is one of those fields, where the online world is flooded with plain ignorance and sometimes malicious misinformation.

However, during my work at the Lazzaretto Nuovo, I have often had medical researchers from all over the world on visits. They seem to be naturally attracted to the place for some reason.

The following is what I have gathered from such visitors to the museum.

Caveat: if you have reason to think some of the following account is incorrect, I’d really appreciate your feedback. In any case, be warned that there are no clear answers. Everything depends, there are always exceptions, and there’s a good deal of conjecture too, for good measure.

So, for starters, our bodies cannot reliably develop lasting immunity to bacterial infections. Vaccines are generally for viral infections, not bacterial infections.

It is therefore not possible to create a long-lasting vaccine against the plague.

However, the lack of immunisation doesn’t mean we’re all equally exposed.

Apparently, there’s a genetic side to our body’s response to yersinia pestis, and some individuals are simply less likely to get it than others.

Add natural selection to the mix, and there’s a possible and plausible explanation why the plague no longer exists in Europe, while it happily lingers in other parts of the world.

The lack of long-term immunisation doesn’t mean that there can’t be some short-term protection.

An individual, who has had the plague and recovered, might have some short-term defences, as their immune system has just fought the infection. They might therefore be less likely to catch it (or at least the same strain) again immediately afterwards.

I don’t know how long such a short-term protection can last, but a year or two seems a reasonable guess.

Such short-term partial immunisation offers a possible explanation for the waves of the plague.

For the first century or so after the arrival of the plague in Europe, it returned repeatedly in waves.

The key here is ‘in waves’. The plague didn’t arrive in Venice, to be endemic and constantly present, slowly killing people at a more or less constant rate. Rather, it arrived, burned violently through the city, and then burned out, leaving behind the scarred human embers.

Why did it disappear, rather than linger?

One explanation is, that, as an infection arrived, over a period of one or two years, most of those without a genetic indisposition to the plague, got it, and a part (roughly half) of those died. The survivors were unlikely to contract the infection immediately afterwards, so at some point, the bacteria couldn’t find new victims, waned and disappeared.

The next wave would require both a new external source of the plague, and for enough time to have passed for the short-term protection of the survivors to fade. Only then could the plague get a foothold again, and start the next wave.

With each successive wave of the plague, the proportion of the population with a genetic indisposition to the plague increased, until they made up almost the entire population.

Modern treatment

Bacteria were only discovered in the late 1800s.

It was during the third plague pandemic in Asia that yersinia pestis was identified.

Being a bacterium, the plague can be treated with antibiotics, but antibiotics were only discovered in the early 1900s.

For most of human history, there were no reliable remedies against the plague.

The plague is still with us.

There are regular cases in Mongolia, in Madagascar and in the USA. The bacteria typically survives in wild rodent populations, like rats, rabbits, beavers, squirrels and so on.

Humours and bad air

So, we know many things about the plague that our forefathers and -mothers didn’t know, and couldn’t know.

Our reaction to such a pandemic — as we have seen with Covid — is decided by how we perceive the disease and its causes, that is, how we interpret the world around us.

Our perception of Covid was (mostly) governed by our scientific approach to medicine, so science and modern medicine were our primary strategy against the disease, and they served us well.

Our forefathers and -mothers didn’t have that.

Modern science and medicine didn’t exist yet.

So how did they perceive the disease and the epidemic, and — based on that perception — how did they act?

Humours

We have to go way back in time, to the ancient Greeks — Aristotle and Hippocrates to be more specific — for the answer.

The model of health and disease they developed, would be the dominant view for over two millennia, until after the discovery of bacteria in the late 1800s.

Therefore, when the plague arrived in Venice in 1348 — besides the simplistic view that it was God’s punishment — this was the model used to understand the plague, and to guide people’s reaction to it.

The basic idea was that our bodies contain four essential fluids, called humours.

They were blood, phlegm and black and yellow bile.

In a healthy person, the four humours were in balance. However, if something provoked an imbalance, the person would get sick. Different combinations of imbalances between the four humours corresponded to different diseases.

Each humour had specific characteristics. They were associated with the basic elements of earth, wind, water and fire, so they were dry, wet, cold and hot.

For example, blood was considered hot, so if a person had a fever, bloodletting with leaches could be used to lower the level of the hot element, thus reducing the fever.

This is just one example of how perception determines a line of action.

Miasma

Now, imagine somebody gets a scratch from a rusty nail, gets an infection and dies.

This was explained with the infected wound causing an imbalance of the humours, which led to the death of the person. It is an easy reasoning, as there is a clearly visible cause of the imbalance, which led to death.

How can contagious diseases fit into this model?

Again, imagine four people spending some time in a room, without meeting each other. They’re in there at different times. Afterwards, they all come down with the same symptoms, and die in similar ways. They have never met, and the only thing they share, is that they spent some time in that room.

To resolve such a conundrum, the ancient Greeks invented miasma.

Miasma were invisible ‘thingies’, which could float around in the air or attach to persons or objects. If they entered the body of a person, they would cause an imbalance of the humours, and hence disease.

The explanation for the imaginary case of the four persons in the same room at different times, was simply that the room was full of a kind of miasma, which caused a specific imbalance of the humours corresponding to the observed disease. They were all exposed to the same miasma, and therefore got the same disease.

Based on this model, what we see as contagious disease, spreading from person to person, our forefathers and -mothers saw as more of an environmental problem. Some places, areas, and spaces contained miasma which could cause disease in those who went there.

There was also, however, some concept of contagion, as miasma could attach to persons and objects, and in that way they could serve as agents for the spread of the disease. In fact, the expression mal contagioso was commonly used for infectious diseases.

Where did the miasma come from? Why would there be miasma in some spaces, and not in others?

The response to this was that the miasma appeared spontaneously if the conditions were ‘right’.

They would literally auto-generate when and where the conditions for their presence were present.

So, what were the ‘right’ conditions for the generation of miasma?

They were all those conditions which people perceived as unpleasant or causing unease. It could be, for example, unburied cadavers in a state of decomposition, or piles of rotting rubbish, or in Venice, the stench of rotten eggs (sulphur) which emanates when the bottom of the lagoon is turned over.

What all these situations have in common is stench.

Hence, the general perception was, that foul smelling things and places caused disease, through the spontaneous generation of miasma in such places.

The causality was therefore — in this model of health and disease — that things and places with foul smells led to miasma which led to disease, and possibly death.

What could they do?

This is a line of reasoning which is actionable, beyond thoughts and prayers, which was all the orthodox explanation of God’s punishment offered.

Based on the model of humours and miasma, specific actions could be devised to break the chain of cause and effect.

Methods were invented to remove miasma from spaces, and to prevent them from generating in the first place.

After what we’ve just discussed, the answers are almost blindingly obvious.

If a space seemed infected or at risk, ventilate. Blow the miasma away, and remove the foul stench.

Replace unpleasant smells with good smells. Perfume, incense, vinegar.

Lo and behold! The word ‘perfume’ has ‘fume’ in it. An easy way of ‘perfuming’ something, was to expose it to the fumes of burning herbs, such as rosemary and juniper.

In Venetian documents, when they talk about ‘perfuming’, they meant exposing spaces or objects to the fumes of a fire, which can be anything from a bonfire to a small brazier.

Wrong reasoning, correct result

Why didn’t the Venetians — and the Europeans in general — realise that their conceptual model for health and disease was all wrong?

Part of the reason is that there were no competing models, if not the orthodox explanation of God’s punishment. The problem with that was, that it offered no remedies besides thoughts and prayers.

It left people without agency.

Another reason was, that many of the remedies worked, and some quite well.

Confronted with a contagious disease, ventilation is good.

The idea of miasma floating around in the air, is not that far from our knowledge of infected droplets as a means of contagion.

Miasma attaching to persons or objects led to the use of quarantine, and to social distancing.

The common use of vinegar to treat objects of paper and metal worked very well. Vinegar is a natural disinfectant, and can kill bacteria. If coins were soaked in vinegar, and letters sprayed with vinegar, they were, in fact, disinfected.

They used vinegar as a means of replacing a foul smell with a more pleasant smell, but the germs died anyway. That the reason for using vinegar was all wrong, does no harm to its efficacy.

There are numerous cases where a totally wrong reasoning — as seen with modern eyes — led to quite efficient results.

Perception is everything

All this might seem absurd to those of us, who have accepted, that modern science offers better models for understanding the world.

At the face of it, the whole idea of humours and miasma qualifies as little more than baseless superstition.

Nevertheless, this was the dominant model in Europe for understanding health and disease until the late 1800s or even the early 1900s, when the “germ theory”, as it was derogatorily called, appeared.

That change didn’t happen without a struggle. The “germ theory” wasn’t accepted by the medical and scientific establishment for a long time. After all, most of their careers and reputations were built on the idea of humours and miasma. It took a long and hard fight, which destroyed more than one promising career of younger doctors with open minds.

Established truths don’t give way easily, even when they’re not true.

From a historical perspective, it is important that we understand what people in the past believed, and how they reasoned because their beliefs determined their reasoning, and therefore the actions they took, and even which actions they could possibly take.

Some of these ideas are still with us, in words in common usage. The disease malaria is an infection cause by a parasite, transmitted by mosquitoes in swampy areas, where the insects can breed.

What does the name actually mean? The word ‘malaria’ is mal-aria — literally bad air — that is, smelly air full of miasma causing the disease.

Our ancestors never connected malaria with mosquitoes because their model for understanding the disease didn’t allow for that connection. They instead connected the disease to the foul stench of these swampy areas.

Next episode

Time’s up, I’m afraid.

This subject is much too large for one episode, so the next few episodes will also be about the plague.

Next time, we talk about how the events unfolded in Venice after the initial chock, and how the Venetians slowly learned to govern the plague.

As they realised that no cure worked, and that the plague didn’t disappear of its own accord, they focused on the only workable way forward: prevention.