How fast can plague get to you? Discussing pandemics through our doomsday scenario

An odd question? Maybe so, yet behind that, there is a very real concern about the ability of modern man to ensure health and stop any potential pandemic right in its tracks. The reason that plague is so deeply embedded in the popular culture and public imagination is the devastating effect it had on the medieval world. The stories of the 14th century pandemic, known as the Black Death or the Black Plague survived to this day and are a chilling reminder on the fragility of the very survival of mankind.

Of course, the medicine advanced significantly within the 700 years or so since the mid-1300s outbreak and today, plague can be effectively treated when diagnosed early. In fact, efforts undertaken by numerous governments and international organization managed to bring this disease to the brink of extinction, effectively eliminating the chances for another global pandemic. So, unless you’re planning a trip to Madagascar or sub-Saharan Africa, the chances for ever getting infected with plague are close to zero.

The Scenario

Let’s imagine plague evolved and the new genome is changed significantly enough so that antibiotics treatment just isn’t effective anymore. And it’s not a far-fetched scenario, scientists have been warning for years now that our excessive reliance on antibiotics is making infectious diseases adapt faster, creating a chance for them to become antibiotics-resilient.

The question is this – if that happened right now, how fast would the plague get to you? This question is the question of the very survival of mankind in a case of an outbreak of the disease we have no means to treat as of now.

Together, we will look at the facts, relying equally on history, the experience of the Black Death and on the cutting-edge approaches and models in the science of epidemiology in order to get the answer. If there was a plague outbreak today and the antibiotics proved to be ineffective, what would be our odds of surviving?

The Great Plague – Europe Revisited?

Europe has already gone through numerous plague epidemics throughout its history. The most notable of them certainly is the Great Plague, the Black Death of the 14th century. For just four years, between 1347 and 1351, this disease has killed between 35 and 60% of the total European population.

So, if there was an outbreak of antibiotics-resilient plague today, what impact would it have on Europe? Below, we give a table with the estimates of how fast would plague reach different European countries if the outbreak happened today. For the hypothetical locations of the outbreak, we chose three countries that have experienced plague outbreaks in the 21st century.

In the text below, we will elaborate on what considerations need to be taken into account when making these estimates, detailing the relevant models and findings in epidemiology, the historical factors that lead to the Great Plague of the 1300s and the physiological and biological characteristics of the disease itself.

The Science of Epidemiology

Epidemiology is not one exact science, but a term denoting the study and analysis of the distribution and various factors related to disease spread in certain conditions and populations. In other words, it aims to give answer to the question why do some people get sick, what were the factors that contributed to that and could it have been stopped if certain steps were taken.

In doing so, epidemiology relies mostly on biology and microbiology, as well as medical sciences, and secondary, it consults with the knowledge from other sciences such as statistics or social sciences in order to produce thorough, detailed and well-rounded studies. Some of the major fields of epidemiology include:

  • Causes of disease
  • Transmission
  • Outbreak investigation
  • Disease surveillance
  • Forensic epidemiology
  • Occupational epidemiology
  • Screening
  • Monitoring
  • Clinical trials

All these different fields and their specific results are taken into account when epidemiologists produce their final analysis. Their findings are considered to be the fundamental part of public health and determining factor in shaping the official policies. In ideal circumstances, epidemiology will be primarily focused on identifying risk factors and preventive healthcare.

Mathematical models in the study of infectious diseases

In achieving its goals, epidemiology relies on a number of mathematical models, theories and formulas in order to project the progress of a given infectious disease within certain static or dynamic circumstances, thus determining the most likely outcome of a potential epidemic.

While the exact models used for epidemiological analysis (such as stochastic, deterministic or SIR) can be very complex, involving very precise calculations and equations with a large number of variables, we can mention that all these models rely on a number of assumptions; naturally, the validity of assumptions  is what will influence the validity of final results the most. Here, we will consider two most important assumptions for our hypothetical scenario.


Epidemic is defined as a rapid spread of infectious disease to a large number of people in a given population within a short period of time, usually two weeks or less. Epidemics are classified in two distinct groups, depending on the cause of outbreak:

  • Common source outbreak
  • Propagated outbreak

The latter denotes those epidemics that are spread from person to person, while for former, the affected individuals are all exposed to common agent. In our hypothetical scenario, we will assume that epidemic starts with a common source outbreak (exposure to infected rat fleas in a given area, leading to bubonic plague), but evolves into an epidemic with propagated outbreak (specifically, leading to pneumonic and septicemic plague).


Modes of transmission are one of the crucial variables determining both the outcome of an epidemic and optimal ways to prevent it. While there are numerous identified ways of transmission (airborne, arthropod, biological, colostral etc), for our hypothetical scenario, modes of transmission are already predetermined by the known biological and bio-physiological properties of the bacterium causing plague. So, modes of transmission considered will be:

  • Airborne (in case of pneumonic plague)
  • Arthropod (in case of bubonic and septicemic plague)
  • Contact (in case of septicemic plague)

Plague – A Centuries-Old Killer

Plague, known by many other names given to it throughout history such as the Black Plague or the Black Death, is an infectious disease caused by a strain of bacteria Yersinia Pestis. This disease is highly infectious and with an extremely high mortality rate if left untreated, leading to death in up to 70% of patients who didn’t get necessary medical attention and treatment.

The symptoms of plague tend to appear within a week since exposure to the bacteria and they include:

  • Fever
  • Weakness
  • Headache
  • Flu-like symptoms

Known throughout the work for its lethal outbreak in the Middle Ages, plague continues to captivate the imagination of many, still being present in popular culture. In fact, the Great Plague outbreak of the mid-1300s still serves as a kind of stereotype that influenced the way man thinks about pandemics. If you just take a look at countless movies, fiction novels and other artworks dealing with a doomsday epidemic, you can easily notice the influence of the descriptions of the bubonic plague epidemic.

However, this presence of plague in the imagination of contemporary culture often leads to confusion about its characteristics, origins, spread mechanisms and types. For example, many assume that bubonic plague is just another name for this disease, while in reality it is a term denoting one of three recorded forms of plague. As history would have it, bubonic plague was made famous due to the fact that it was the exact type that wreaked havoc throughout the medieval world.

Contrary to popular belief, bubonic plague isn’t that different in terms of mortality rates or speed of infection spread from other forms. We could say that the destructive impact this type of plague had on medieval world is purely coincidental and any other form could have done the same at that point in history. So in order to understand the real danger of plague today, we need to go back to the basics and look at all the forms of this disease with their characteristics and specifics.

Yersinia Pestis

Yersinia Pestis is a bacterium responsible for all three identified types of plague. It belongs to the Gram-negative non-motile rod-shaped coccobacillus, with no spores. In nature, Y. Pestis usually lives within wild rodents and their fleas. At the same time, transmission from fleas to humans via flea bites has been identified as the main mechanism of transmission and was probably also responsible for the Black Death epidemic in the 14th century since mice and rats were very common both on the ships (allowing the disease to spread throughout the medieval world) and in the cities. This fact was used by scientists to explain why urban areas were significantly more affected than rural ones, although in both cases, the death toll was massive.

However, unlike medieval people, today we have very successful tools for battling Yersinia Pestis. A vaccine that can be administered to high-risk individuals has been successfully developed and although it might sound a bit odd given the lethal outcome of the historic pandemics, today plague cases can be successfully treated with simple antibiotics.

Contrary to popular belief, plague still exists today, although it is localized to sub-Saharan Africa and Madagascar. Cases reported there comprise up to 95% of all annual cases of plague in the 21st century.

This bacterium is responsible for all three identified forms of plague. The differences between them are primarily based on the location of the infection, but also on different routes of transmittion. These questions will all be discussed in more detail below.

Bubonic Plague

Bubonic plague, the type responsible for the death of 30-60% of European population during the Black Death pandemic in the 14th century, is a type of plague mainly spread by infected fleas from small mammals such as rodents or exposure to the body fluids of a plague casualty, whether human or animal.

Bubonic plague enters human body through the skin and travels through the lymphatic system to the lymph node, causing it to swell and eventually break, causing severe pain and significantly increasing the risk of infection spread. The symptoms include:

  • Chills
  • Flu-like symptoms and general malaise
  • High fever (> 39°C)
  • Muscle cramps and spasms
  • Seizures
  • Swollen and painful lymph glands
  • Gangrene on extremities and tissue necrosis (toes, fingers, lips and the tip of the nose) causing excruciating pain
  • Heavy breathing
  • Vomiting blood
  • Black dots on the skin
  • Delirium

In a vast majority of cases, bubonic plague is transmitted via the bite of the rat flea (Xenopsylla cheopis), but in rare circumstances, it can spread like septicemic plague, via direct contact with infected tissue or exposure to cough of infected human. The bacterium, Yersinia Pestis remains harmless to the flea, but it does eventually kill the animal it lives on. However, the flea migrates to another host after the death of original one, thus contributing to the faster spread of infection.

Septicemic Plague

While septicemic plague can often be caused by flea bite, just like bubonic plague, it can often be transmitted through open wounds or through exposure to infected droplets of moisture (like from coughs or sneezes). However, the main difference is that septicemic plague is classified as an infection of the blood and as such, it causes a different array of symptoms, eventually leading to disseminated intravascular coagulation and death. When left untreated, septicemic plague is even more lethal than bubonic plague, causing death in 99% of untreated patients.

The usual and noticeable symptoms of septicemic plague don’t necessarily appear prior to lethal outcome, which makes this disease even harder to diagnose in time. But, luckily, it is the rarest of the three forms with less than 500 reported cases annually. The common symptoms include:

  • Abdominal pain
  • Bleeding underneath the skin
  • Blood clotting problems
  • Bleed from mouth, nose and rectum
  • Diarrhoea
  • Fever
  • Chills
  • Nausea
  • Organ failure
  • Violent vomiting (sometimes vomiting blood)
  • Shock
  • Tissue necrosis

In order to prevent fatal outcome, this type of plague needs to be treated within 24 hours since the infection. Fast reaction can reduce mortality rates to as low as 4-15%, while the untreated infection will almost always lead to death. This is why in medieval times it was practically impossible to survive septicemic plague.

Pneumonic Plague

Pneumonic plague is classified as a lung infection and can be caused either by prior plague infection of other type or by inhaling infected droplets. The symptoms usually manifest between three and seven days after the initial exposure. It is more serious, yet less common type of plague compared to bubonic plague, with mortality rates reaching 100%. According to many scientists, it was the pneumonic, not bubonic plague that was responsible for the famous Black Death of the mid-1300s.

Pneumonic plague infection leads to a characteristic array of symptoms with coughing up blood being the most common one. The illness progresses rapidly, developing into severe pneumonia and, eventually, respiratory failure and shock. If left untreated, pneumonic plague can cause death in as little as 36 hours. Others symptoms include:

  • Fever
  • Flu-like symptoms
  • Headaches
  • Weakness
  • Nausea
  • Pneumonia
  • Shortness of breath
  • Chest pain
  • Cough (usually coughing up blood)
  • Bloody or watery sputum

The medical experts differentiate between two causes of pneumonic plague. The primary cause is inhalation of aerosolised plague bacteria and the secondary, when septicaemic plague spreads into the lungs.

Unlike bubonic plague, pneumonic type doesn’t need a non-human carrier, or in medical terminology, it’s not vector-borne, instead, it can easily spread from one person to another. This is why there is a significant consensus about the claim that even if bubonic plague was the notorious Black Death, pneumonic plague must have been present at the same time, contributing to the rapid spread of the disease and its subsequent grim results.

The Black Death (1347-1351)

The Black Death, also known as the Great Plague or the Black Plague was one of the most devastating pandemics in the recorded history which claimed lives of between 75 and 200 million people throughout Europe and Asia, reducing the global population from estimated 450 million to 350 million. It had a profound impact on medieval world, especially Europe where between 35 and 60% of total population was killed due to plague pandemic. It took more than two centuries for the world population to return to the levels prior to the outbreak.

Aside from this grim impact on the demographic structure of the world, black plague had a number of other consequences, including a change in the approach to medicine and changes in social structure and organization. Culture was influenced too, with people believing the end of the world is nearing and even after the initial pandemic disappeared, the arts from the period continued to revolve around morbid fascination with death.

The story of the Black Plague survived to contemporary times, still carrying the same chilling message about the vulnerability of man to the previously unknown diseases. Modern fiction remains fascinated by the possibility of the new pandemic, while the relevant institutions do their best to prevent another outbreak through numerous means. So, even seven centuries later, the horrors of the Black Death remain alive in the stories and imagination, and this long survival of the story serves as another testimony to the impact this pandemic had on the world.

Asian Outbreak

Yersinia pestis, the bacterium causing the plague is commonly present in fleas carried by rodent populations in central and western Asia, northern India and Uganda. However, it is not sure where it originated exactly. As for Black Death of the 1300s, the historical accounts and archaeological evidence point to the fact that patient zero probably died somewhere in Kyrgyzstan, around 1338-1339. From there, the Black Plague spread to China and India. As of 2010 most scholars agree that China played a vital role as the epicentre of the outbreak.

On one hand, China was an important trading centre even back in that time, so rats infected by carrier fleas could have been transported to Europe via shipping routes from that time. It is estimated that before Black Death even reached Europe, it has claimed lives of more than 25 million people in China. On the other hand, the Mongolian conquest was another important route of transmission.

By the year 1347, Mongolian army, now infected by plague in large amounts reached the port city of Kaffa in Crimea. During the siege, the Mongolians catapulted infected corpses over the city walls in order to infect the population. As people started fleeing the city, they brought the infection with them to Italy.

Spread to Europe

By October 1347, the plague reached Sicily, carried by Genoese merchants fleeing Kaffa. By January 1348, both Genoa and Venice were affected and sometime later, there was an outbreak in Pisa, which was considered to be the entry point to northern Italy. By that time, the authorities noticed the relation between Genoese arrivals and the spread of infection, so they banned the entry to Italian ports. However, one ship which was affected by the ban docked in Marseilles, spreading the disease to France.

By the summer of 1348, France, Spain, Portugal and England were affected too. By 1350 the Black Death swept across Germany and Scandinavia, eventually reaching Russia in 1351. As is evident, seafaring nations with strong and diverse trade relations were those most affected. Isolated rural communities in the hard to reach areas of Europe were mostly safe from the pandemic.

Spread to the Middle East

From Crimea and southern Russia, rodents infected with plague entered the Middle Eastern territories, causing severe depopulation and permanent change in the economic and social structures. In autumn 1347, the first outbreak in the Middle East happened in Alexandria in Egypt, through the ports on the Black Sea. By the end of the same year, Black Death spread to Gaza as well as to the eastern coastal cities in Lebanon, Syria and Palestine. By late 1348 and early 1349, the disease reached Antioch in the present day Turkey, spreading from there to Asia Minor, affecting trading and cultural centres such as Mecca and Baghdad. Finally, by the year 1351, at roughly the same time plague spread throughout Russia, it also reached the very south of the Arabian Peninsula with the outbreak in Yemen.

The Great Plague Aftermath

The Black Plague pandemic had a profound effect on the medieval world, causing millions of deaths, completely changing demographic structure of the old world. Through these processes, the Black Death subsequently had a profound impact on the societies themselves, especially in the domains of religion, medicine, art and economy, including class relations and dynamics.

Death Toll

While only rough estimates are available, scientists mostly agree that just within four years (from 1347 to 1351), between one third and a half of total European population died in the plague pandemic of the 14th century. The disease reduced the total world population by as much as 100 million people.

The heavily populated areas with multiple urban cities were the ones that were stricken the hardest due to the increased presence of rodents, bad hygiene and many travellers and traders who could potentially introduce the contagion to the area. Due to the fact that the pandemic originated in trading centres and major ports in Crimea and China, other port cities throughout Europe were the first to be affected and suffered heavy casualties. For example, England, as a major maritime power was extremely hard hit, losing up to 70% of total population of the country within just four years, declining from 7 million to just 2 million. On the other hand, rural areas in, for example, Hungary and Poland were largely unaffected with number of casualties incomparably lower than in urbanized areas of medieval Europe.

In Asia, China was struck especially hard, but years of war, famine and other diseases probably strongly contributed to that fact. Regardless, bottom line is that by 1334, China lost up to 80% of the population, and by 1351, the total population shrunk from 125 million to 65 million.

Middle East, including northern parts of Africa, was also hit, but it is a lot more difficult to get to the precise estimate. Many historians and contemporaries of the plague recorded that much of the rural population fled their lands before the plague arrived there, leaving whole towns depopulated, but the fate of the former residents remained unknown. However, for those urban centres that we have precise data for, the casualties were very high. Gaza lost 10.000 citizens over the course of one year, while Aleppo recorded a staggering and chilling 500 deaths daily. But even this tragedy is shadowed by Damascus which, at the peak of the epidemic, lost 1000 citizens every day. By the time pandemic subsided, Syria has lost around 40% of the population. This means that, despite the grim statistics, Middle East suffered slightly less casualties as compared to Europe due to reasons which are still debated to this day.

Social Consequences

During the first years of the pandemic, the European healers were shown to be ineffective in stopping or explaining the disease which is why majority of the population turned towards other explanations, including astrology, supernatural forces or mysterious effects of natural forces (like earthquakes) and even certain groups of people. The theory that plague was caused by Jews poisoning the wells was very popular in certain parts of Europe, leading to massacres and persecution of Jewish population.

The government authorities also made a series of bad decisions, like banning the exports of foodstuff which just made matters worse, creating famine due to interaction of lack of labour force at home and inability to import food. Those shipments that could actually be sent were usually looted by pirates.

However, many historians also argued that plague had unlikely results which were positive in the long term. For example, once the disease subsided and the panic among the population diminished, the lack of belief in healers was exchanged for a different approach to medicine that focuses specifically on the human body. This change lead to the very foundations of modern medicine and also emphasized the importance of surgery.

Economic Impact

On the other hand, the reduction of population resulted in higher wages and more available land and food for those who managed to survive the Black Death. This dramatically changed the status of rural population for the better and functioned as a strong blow against serfdom. This was mostly because economic inequality between landowners and workers reduced since there was more land and more chances to find work, yet fewer workers available.

What would happen if there was a plague outbreak today?

As was implied at the beginning of the text, the world saw a number of plague outbreaks in the 21st century, in the following countries:

  • Madagascar (most recent in 2017)
  • Peru
  • China
  • Congo
  • Algeria
  • Malawi
  • India
  • Zambia

This goes to show that even when plague outbreak does happen, it is successfully contained and mitigated. But, let’s return to our hypothetical scenario. If the new strain is resistant to known treatments, including vaccines, what would then happen? Let’s start at the beginning.

Where would patient zero be?

It is most likely that patient zero could be found within one of the aforementioned countries which already experienced plague outbreaks. In order to evolve and adapt to new medicines, including antibiotics, the bacteria needs to be active within human hosts and exposed to treatments methods.

For our scenario, we will choose three countries – Madagascar, since the plague affects the largest number of people there, Congo, since the climate and ecology are very suitable for plague-causing bacteria to thrive and finally India which has high likelihood of fast spread of infection due to certain cultural practices regarding the handling of the dead.

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