What is the History of Pandemics

Figure 1. The Justinian Plague is perhaps among the most devastating pandemics in history.

Pandemics have long been a part of human history. This includes various diseases that spread globally and has, in many different periods, created a large-scale population reduction. For ancient periods, pandemics were often conflated with plagues. While the recent COVID-19 pandemic is of concern, many other pandemics have caused far worse social disruption and destruction.

Earliest Evidence for Pandemics

Some of the earliest recorded epidemics may appear by the mid-2nd millennium BCE. Some of these may have been global-scale pandemics but often this information is difficult to piece together since most societies were still without writing. In Mesopotamia, recordings of plague are made in the Old Babylonian period (1800-1600 BCE), which could have been a pandemic that had started in Asia or spread in Asia. By around 1400 BCE, the Hittites mention a plague was spread through their country and that they had asked the gods to spread the disease to their enemies rather than on them. In fact, by 1200 BCE, a great collapse of states occurred, including the fall of the Hittites, and along the eastern Mediterranean, with the Mycenaean Greeks collapsing as well. Texts indicate that great waves of invasions occurred that caused this collapse.

However, it is likely something else triggered this; while nobody knows for sure what triggered these mass migrations and invasions, one possibility is a chain reaction of events across Eurasia led to migrations that pushed groups to take risky invasions of areas such as southeast Europe and Mediterranean region. Pestilence, plagues and global pandemics have been leading reasons as to what caused these migrations and invasions to occur. The events were so pronounced that for 200 years, few written records were produced and this has been called one of the earliest great 'Dark Ages' due to the scale of the impact these events had on established complex societies around the Mediterranean region.

One relatively well-known early epidemic, and one of the first virus-based epidemics, was called the Athenian Plague, which fatally weakened the power of Athens in the 5th century BCE and was likely a major outbreak of typhoid. From around 430-426 BCE, historians believe this typhoid likely became widespread in Athens, killing not only many of its citizens but also weakening its army. This led Athens to lose power to its competitor city-states, particularly Sparta, in the Peloponnesian War. Athens would not regain any significant influence for generations, as the population had to recover from the devastation of the outbreak.

While other states may have been affected by this outbreak, the death rates were so high and sudden that in a way it likely limited the impact of the outbreak mainly to Athens. This possibly explains why it was mainly Athens that weakened and not other states. Cholera may have been the most common form of epidemics that could have transformed into global or regional pandemics. In fact, cholera would remain among the most frequently reoccurring epidemics and pandemics until the 20th century, whereby then improved sanitation and drinking water had reduced its effects.

Late Antiquity and Medieval Pandemics

The pace of knowledge on pandemics increased in Late Antiquity. One of the first recorded in this period was the Antonine Plague in 165-180 CE, likely caused by smallpox brought back from the Middle East or elsewhere in the Roman empire, where the pandemic killed perhaps tens of thousands in the capital. Millions may have died globally form this devastating pandemic. One of the first large-scale killers comparable in scale to the Black Death was the Plague of Justinian, which likely started around 541 CE. A likely killer was an early form of the bacterial bubonic plague, similar to the Black Death plague in the 14th century. This was also one of the first to likely span nearly every major Old World city. It is estimated that Constantinople lost 40% of its population with up to half of Europe's population being affected or killed by this plague.

In fact, this devastation likely kept Europe in a prolonged Dark Age, where few recorded historical records were produced because of very low population levels in the region until about the 10th century. By the 8th century, only small towns existed through most of Europe and the population was still very low compared to its level seen in the Late Roman period in the 4th century. Similarly, perhaps the same or similar plagues weakened the Sasanian Empire in the 7th century, which led to that state becoming weak and eventually it collapsed during the Islamic invasion in 651. The Sasanians were a very urban society, making them vulnerable for the disease to spread rapidly through their cities.

Overall, no disease would approach the scale of the Justinian Plague until the Black Death. Recent work has suggested that the plague started in Central Asia before spreading to the Byzantine Empire, the Near East, and then Europe. The Byzantine Emperor Justinian did, in fact, contract the plague but he managed to survive it.

A contender for the most devastating pandemic in history is the Black Death between 1346–1353. While it does seem that pandemics did greatly shape the course of history in earlier periods, such as the Justinian Plague and typhoid that likely weakened Athens, few events shaped global history as the Black Death. The Black Death weakened many states, including those across the Middle East, China, India, and Europe. Some regions did not recover quickly, while others were never able to recover completely until the 19th century, such as parts of Italy.

For Europe, it took over 200 years for the population to approach levels of the early 14th century. Historians have argued that although the plague was devastating, it may have helped to spark the Renaissance and innovation, as new inventions were developed because of population decline. Regardless, the remnants of this plague have been found to reoccur or break out in various regions in the Old World, including in Central Asia where it likely originated, until the early 20th century.

Recent Pandemics

Figure 2. The Spanish Flu killed millions and was the last time the global population declined due to a pandemic.

Almost comparable in scale to the Black Death are the series of mostly smallpox outbreaks that occurred in the New World between 1492 and 1850s, caused by Europeans bringing the disease to Native American populations that had no built immunity to this disease. The Aztecs are a famous example of an empire collapsing mostly because of smallpox devastating the population, but nearly every Native American population, starting with the first populations that greeted Christopher Columbus and other explorers, experienced high death rates, some to the point where they had nearly 100% fatality rates. As a percentage of deaths, these outbreaks were probably the most devastating in history relative to the scale in which they occurred.

The more recent flu pandemics are only recorded to be a major problem at global scales starting in the late 19th century. The so-called 'Russian Flu' started in Siberia and Kazakhstan in 1889 and likely killed nearly 400,000 in North America, Asia, Africa, and Europe. The so-called Spanish Flu, perhaps the most infamous until recently, in 1918 led to about 50 million deaths worldwide. It likely started in China, although it is not clear to this day what the origin of this flu was. The flu became evident as an outbreak in Madrid, which is why it was called the Spanish Flu as news services began to report it (Figure 2). It spread globally throughout 1918 and did not begin to disappear until 1919, likely fading because it had either killed those who were not immune to it or people developed immunity if they did not die from it.

This pandemic was perhaps the first to travel so far and fast due to modern transport. The so-called Asian Flu in 1957 also led to a global-scale pandemic, but it was contained by 1958 after a vaccine had been developed. It was the first pandemic that was successfully contained after a vaccine had been derived, although it probably killed over a million people. One pandemic stands out among all these is AIDS, which has been classified a pandemic by the World Health Organization. It has been estimated that over 35 million people have died from this pandemic. Its origin is believed to have been first present in the 1920s but it did not become identified until 1981.

Severe Acute Respiratory Syndrome (SARS) is considered among the most recent viral diseases that began in 2003. Although initially, the global community was slow to contain it, eventually the impact of SARS became limited as containment and quarantine became effectively used. This pandemic is perhaps the least deadly, with less than 1000 deaths recorded.

Summary

Pandemics have been regular throughout history. We see that they have changed the fortunes of societies, sometimes devastating them, such as Native American populations, to the point where they have never really recovered to the population levels seen earlier. More pandemics have been likely, as many have been mistaken for forms of local plagues, even if they were pandemics that traveled along trade routes and with travelers. Pandemics in recent history have been more commonly based on forms of flu. Interestingly, few types of flu-like pandemics have been recorded until the late 19th century. However, this simply could be because influenza, or flu, was not known until the 18th century in most of the West.