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Visualizing the History of Pandemics

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History of Pandemics 16 March 2021 Update

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The History of Pandemics

Pan·dem·ic /panˈdemik/ (of a disease) prevalent over a whole country or the world.

As humans have spread across the world, so have infectious diseases. Even in this modern era, outbreaks are nearly constant, though not every outbreak reaches pandemic level as COVID-19 has.

Today’s visualization outlines some of history’s most deadly pandemics, from the Antonine Plague to the current COVID-19 event.

A Timeline of Historical Pandemics

Disease and illnesses have plagued humanity since the earliest days, our mortal flaw. However, it was not until the marked shift to agrarian communities that the scale and spread of these diseases increased dramatically.

Widespread trade created new opportunities for human and animal interactions that sped up such epidemics. Malaria, tuberculosis, leprosy, influenza, smallpox, and others first appeared during these early years.

The more civilized humans became – with larger cities, more exotic trade routes, and increased contact with different populations of people, animals, and ecosystems – the more likely pandemics would occur.

Here are some of the major pandemics that have occurred over time:

NameTime periodType / Pre-human hostDeath toll
Antonine Plague165-180Believed to be either smallpox or measles5M
Japanese smallpox epidemic735-737Variola major virus1M
Plague of Justinian541-542Yersinia pestis bacteria / Rats, fleas30-50M
Black Death1347-1351Yersinia pestis bacteria / Rats, fleas200M
New World Smallpox Outbreak1520 – onwardsVariola major virus56M
Great Plague of London1665Yersinia pestis bacteria / Rats, fleas100,000
Italian plague1629-1631Yersinia pestis bacteria / Rats, fleas1M
Cholera Pandemics 1-61817-1923V. cholerae bacteria1M+
Third Plague1885Yersinia pestis bacteria / Rats, fleas12M (China and India)
Yellow FeverLate 1800sVirus / Mosquitoes100,000-150,000 (U.S.)
Russian Flu1889-1890Believed to be H2N2 (avian origin)1M
Spanish Flu1918-1919H1N1 virus / Pigs40-50M
Asian Flu1957-1958H2N2 virus1.1M
Hong Kong Flu1968-1970H3N2 virus1M
HIV/AIDS1981-presentVirus / Chimpanzees25-35M
Swine Flu2009-2010H1N1 virus / Pigs200,000
SARS2002-2003Coronavirus / Bats, Civets770
Ebola2014-2016Ebolavirus / Wild animals11,000
MERS2015-PresentCoronavirus / Bats, camels850
COVID-192019-PresentCoronavirus – Unknown (possibly pangolins)2.7M (Johns Hopkins University estimate as of March 16, 2021)

Note: Many of the death toll numbers listed above are best estimates based on available research. Some, such as the Plague of Justinian and Swine Flu, are subject to debate based on new evidence.

Despite the persistence of disease and pandemics throughout history, there’s one consistent trend over time – a gradual reduction in the death rate. Healthcare improvements and understanding the factors that incubate pandemics have been powerful tools in mitigating their impact.

March 15, 2021 Update: Due to popular request, we’ve also visualized how the death tolls of each pandemic stack up as a share of total estimated global populations at the time.

Pandemic Death Toll by Share of Population - Supplemental

Wrath of the Gods

In many ancient societies, people believed that spirits and gods inflicted disease and destruction upon those that deserved their wrath. This unscientific perception often led to disastrous responses that resulted in the deaths of thousands, if not millions.

In the case of Justinian’s plague, the Byzantine historian Procopius of Caesarea traced the origins of the plague (the Yersinia pestis bacteria) to China and northeast India, via land and sea trade routes to Egypt where it entered the Byzantine Empire through Mediterranean ports.

Despite his apparent knowledge of the role geography and trade played in this spread, Procopius laid blame for the outbreak on the Emperor Justinian, declaring him to be either a devil, or invoking God’s punishment for his evil ways. Some historians found that this event could have dashed Emperor Justinian’s efforts to reunite the Western and Eastern remnants of the Roman Empire, and marked the beginning of the Dark Ages.

Luckily, humanity’s understanding of the causes of disease has improved, and this is resulting in a drastic improvement in the response to modern pandemics, albeit slow and incomplete.

Importing Disease

The practice of quarantine began during the 14th century, in an effort to protect coastal cities from plague epidemics. Cautious port authorities required ships arriving in Venice from infected ports to sit at anchor for 40 days before landing — the origin of the word quarantine from the Italian “quaranta giorni”, or 40 days.

One of the first instances of relying on geography and statistical analysis was in mid-19th century London, during a cholera outbreak. In 1854, Dr. John Snow came to the conclusion that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method revealed a cluster of cases around a specific pump from which people were drawing their water from.

While the interactions created through trade and urban life play a pivotal role, it is also the virulent nature of particular diseases that indicate the trajectory of a pandemic.

Tracking Infectiousness

Scientists use a basic measure to track the infectiousness of a disease called the reproduction number — also known as R0 or “R naught.” This number tells us how many susceptible people, on average, each sick person will in turn infect.

Measles tops the list, being the most contagious with a R0 range of 12-18. This means a single person can infect, on average, 12 to 18 people in an unvaccinated population.

While measles may be the most virulent, vaccination efforts and herd immunity can curb its spread. The more people are immune to a disease, the less likely it is to proliferate, making vaccinations critical to prevent the resurgence of known and treatable diseases.

It’s hard to calculate and forecast the true impact of COVID-19, as the outbreak is still ongoing and researchers are still learning about this new form of coronavirus.

Urbanization and the Spread of Disease

We arrive at where we began, with rising global connections and interactions as a driving force behind pandemics. From small hunting and gathering tribes to the metropolis, humanity’s reliance on one another has also sparked opportunities for disease to spread.

Urbanization in the developing world is bringing more and more rural residents into denser neighborhoods, while population increases are putting greater pressure on the environment. At the same time, passenger air traffic nearly doubled in the past decade. These macro trends are having a profound impact on the spread of infectious disease.

As organizations and governments around the world ask for citizens to practice social distancing to help reduce the rate of infection, the digital world is allowing people to maintain connections and commerce like never before.

Editor’s Note: The COVID-19 pandemic is in its early stages and it is obviously impossible to predict its future impact. This post and infographic are meant to provide historical context, and we will continue to update it as time goes on to maintain its accuracy.

Update (March 15, 2020): We’ve adjusted the death toll for COVID-19, and will continue to update on a regular basis.

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Misc

A Visual Guide to Human Emotion

For years, humans have attempted to categorize and codify human emotion. Here are those attempts, visualized.

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visual guide to human emotions wheel

A Visual Guide to Human Emotion

Despite vast differences in culture around the world, humanity’s DNA is 99.9% similar.

There are few attributes more central and universal to the human experience than our emotions. Of course, the broad spectrum of emotions we’re capable of experiencing can be difficult to articulate. That’s where this brilliant visualization by the Junto Institute comes in.

This circular visualization is the latest in an ongoing attempt to neatly categorize the full range of emotions in a logical way.

A Taxonomy of Human Emotion

Our understanding has come a long way since William James proposed four basic emotions – fear, grief, love, and rage—though these core emotions still form much of the foundation for current frameworks.

The wheel visualization above identifies six root emotions:

  1. Fear
  2. Anger
  3. Sadness
  4. Surprise
  5. Joy
  6. Love

From these six emotions, more nuanced descriptions emerge, such as jealousy as a subset of anger, and awe-struck as a subset of surprise. In total, there are 102 second- and third-order emotions listed on this emotion wheel.

Reinventing the Feeling Wheel

The concept of mapping the range of human emotions on a wheel picked up traction in the 1980s, and has evolved ever since.

One of these original concepts was developed by American psychologist Robert Plutchik, who mapped eight primary emotions—anger, fear, sadness, disgust, surprise, anticipation, trust, and joy. These “high survival value” emotions were believed to be the most useful in keeping our ancient ancestors alive.

plutchik emotion wheel

Another seminal graphic concept was developed by author Dr. Gloria Willcox. This version of the emotions wheel has spawned dozens of similar designs, as people continue to try to improve on the concept.

willcox feelings wheel

Further Exploration

The more we research human emotion, the more nuanced our understanding becomes in terms of how we react to the world around us.

Researchers at UC Berkeley used 2,185 short video clips to elicit emotions from study participants. Study participants rated the videos using 27 dimensions of self-reported emotional experience, and the results were mapped in an incredible interactive visualization. It is interesting to note that some video clips garnered a wide array of responses, while other clips elicit a near unanimous emotional response.

Here are some example videos and the distribution of responses:

reported emotional reaction to video clips

The data visualization clusters these types of videos together, giving us a unique perspective on how people respond to certain types of stimuli.

Much like emotion itself, our desire to understand and classify the world around us is powerful and uniquely human.

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Mapping the World’s Key Maritime Choke Points

Ocean shipping is the primary mode of international trade. This map identifies maritime choke points that pose a risk to this complex logistic network.

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maritime choke points

Mapping the World’s Key Maritime Choke Points

Maritime transport is an essential part of international trade—approximately 80% of global merchandise is shipped via sea.

Because of its importance, commercial shipping relies on strategic trade routes to move goods efficiently. These waterways are used by thousands of vessels a year—but it’s not always smooth sailing. In fact, there are certain points along these routes that pose a risk to the whole system.

Here’s a look at the world’s most vulnerable maritime bottlenecks—also known as choke points—as identified by GIS.

What’s a Choke Point?

Choke points are strategic, narrow passages that connect two larger areas to one another. When it comes to maritime trade, these are typically straits or canals that see high volumes of traffic because of their optimal location.

Despite their convenience, these vital points pose several risks:

  • Structural risks: As demonstrated in the recent Suez Canal blockage, ships can crash along the shore of a canal if the passage is too narrow, causing traffic jams that can last for days.
  • Geopolitical risks: Because of their high traffic, choke points are particularly vulnerable to blockades or deliberate disruptions during times of political unrest.

The type and degree of risk varies, depending on location. Here’s a look at some of the biggest threats, at eight of the world’s major choke points.

maritime choke point risks

Because of their high risk, alternatives for some of these key routes have been proposed in the past—for instance, in 2013 Nicaraguan Congress approved a $40 billion dollar project proposal to build a canal that was meant to rival the Panama Canal.

As of today, it has yet to materialize.

A Closer Look: Key Maritime Choke Points

Despite their vulnerabilities, these choke points remain critical waterways that facilitate international trade. Below, we dive into a few of the key areas to provide some context on just how important they are to global trade.

The Panama Canal

The Panama Canal is a lock-type canal that provides a shortcut for ships traveling between the Pacific and Atlantic oceans. Ships sailing between the east and west coasts of the U.S. save over 8,000 nautical miles by using the canal—which roughly shortens their trip by 21 days.

In 2019, 252 million long tons of goods were transported through the Panama Canal, which generated over $2.6 billion in tolls.

The Suez Canal

The Suez Canal is an Egyptian waterway that connects Europe to Asia. Without this route, ships would need to sail around Africa, which would add approximately seven days to their trips. In 2019, nearly 19,000 vessels, and 1 billion tons of cargo, traveled through the Suez Canal.

In an effort to mitigate risk, the Egyptian government embarked on a major expansion project for the canal back in 2015. But, given the recent blockage caused by a Taiwanese container ship, it’s clear that the waterway is still vulnerable to obstruction.

The Strait of Malacca

At its smallest point, the Strait of Malacca is approximately 1.5 nautical miles, making it one of the world’s narrowest choke points. Despite its size, it’s one of Asia’s most critical waterways, since it provides a critical connection between China, India, and Southeast Asia. This choke point creates a risky situation for the 130,000 or so ships that visit the Port of Singapore each year.

The area is also known to have problems with piracy—in 2019, there were 30 piracy incidents, according to private information group ReCAAP ISC.

The Strait of Hormuz

Controlled by Iran, the Strait of Hormuz links the Persian Gulf to the Gulf of Oman, ultimately draining into the Arabian Sea. It’s a primary vein for the world’s oil supply, transporting approximately 21 million barrels per day.

Historically, it’s also been a site of regional conflict. For instance, tankers and commercial ships were attacked in that area during the Iran-Iraq war in the 1980s.

The Bab el-Mandeb Strait

The Bab el-Mandeb Strait is another primary waterway for the world’s oil and natural gas. Nestled between Africa and the Middle East, the critical route connects the Mediterranean Sea (via the Suez Canal) to the Indian Ocean.

Like the Strait of Malacca, it’s well known as a high-risk area for pirate attacks. In May 2020, a UK chemical tanker was attacked off the coast of Yemen–the ninth pirate attack in the area that year.

Due to the strategic nature of the region, there is a strong military presence in nearby Djibouti, including China’s first ever foreign military base.

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