What Was The Most Significant Infectious Disease In Every Century?

When looking back through human history, one would be hard-pressed to find an era, civilization, or community that has not been impacted by an infectious disease outbreak. From the bubonic plague to influenza to cholera, epidemics and pandemics the world over have come in many shapes, sizes, and death tolls. But sometimes, the death toll alone doesn’t reflect the true, lasting impact that specific infectious disease outbreaks had on the populations they infected - or those nearby.

So, what was the most significant infectious disease from every century? And what impact did the diseases have on the populations, economies, and environments of the communities they forever altered? And what world was left for the survivors of these pandemics? The answers to these questions, in many centuries, live up to the reputations of their associated infectious diseases.


  • 1000s: Leprosy
    Photo: Vinzenz von Beauvais / Wikimedia Commons / Public Domain

    1000s: Leprosy

    While the origins of leprosy remain definitely unknown, the implications of the disease’s outbreak have left a large mark on human history. After having suddenly gained its stronghold over communities in Medieval Europe in the early 1000s, leprosy remained a longstanding public health issue.

    In an attempt to stifle the spread of the disease, leper colonies were created to quarantine symptomatic individuals. Unfortunately, without any treatment options, those inflicted with the disease were forced to suffer painful skin lesions which left them susceptible to other infection. Though leprosy is still prevalent today, it is largely treatable with antibiotics.

  • 1100-1200s: Influenza

    While large-scale disease outbreaks were relatively minor during the 1100s and 1200s, the diversity of the diseases present at this time all but made up for it. There was a consistent presence of well-known diseases such as measles, smallpox, and ergotism, but concerns surrounding these ailments were all but trumped by the prevalence of various influenza outbreaks.

    These outbreaks continued throughout Europe for the better part of the Middle Ages, well into the 1400s. Interestingly enough, during this same time, many European cities were making great efforts to improve public health conditions and access to water for residents. 

  • 1300s: The Black Death
    Photo: Pierart dou Tielt / Wikimedia Commons / Public Domain

    1300s: The Black Death

    With an estimated death toll between 75 and 200 million people, the Black Death swept across Europe in the mid-1300s and had a lasting and devastating impact on the landscape of the continent forever. Lasting only around four years in total, this outbreak of the plague - known as the “second of the Three Great Plagues” - first made its way into Italy in 1347 via sailors who had been working abroad in areas around China and India. The sailors, who arrived with black boils and spots on the skin, inspired the name of this devastating outbreak.

    It’s believed that nearly half of the European population was killed as the disease spread so quickly that people would die in a matter of weeks, days, or even hours.  

  • 1400s: Syphilis

    The latter half of the 1400s were marked by the steady, and then drastic, spread of the infectious sexually transmitted disease syphilis. What was then often referred to as the “Disease of Naples” or “French Disease,” syphilis made its first large-scale appearance among the soldiers in King Charles VIII of France’s army as they attempted to gain control of Naples in 1494.

    It was shortly after the army gained control of their targeted territory that symptoms of syphilis began to spread, and infection became prevalent. From here, as soldiers returned home, syphilis joined them and continued to spread across more European communities. Then, with the help of the invention of the printing press and the new-found ability to transmit medical information more easily to the masses, syphilis became known as a primary public health crisis in communities across Europe. And because of its uncertain origin, people began associating it with peoples and countries they either believed in came from or for which they had existing prejudices.

  • 1500s: The Columbian Exchange
    Photo: Bernardino de Sahag / Wikimedia Commons / Public Domain

    1500s: The Columbian Exchange

    The Columbian Exchange marks a particularly complicated time in human history, the impact of which is still unmistakably felt today. During this time, different factions of humanity that had been long separated by land and sea were once again reunited. The term Columbian Exchange, which was coined by historian Alfred Crosby, refers specifically to the sudden globalized commingling of not only people and technology but of animals, plants, and diseases.

    As European colonizers and traders expanded their reach into the Americas, Africa, and Asia with the help of faster ships and stronger weapons, they brought a whole slew of diseases with them, their livestock, and plants which quickly ravaged the local populations they met with due in large part to the fact that they had no immunities built up to those particular diseases. Some of the most devastating among them included smallpox, measles, influenza, and typhoid. This deadly combination of diseases wiped out numerous civilizations and took millions of lives.

  • 1600s: Bubonic Plague

    As one of the better-known infectious diseases from human history, the bubonic plague has made a name for itself both in its scale and its devastation. The most historically significant of the many plague outbreaks may be attributed to the epidemic that hit London and, to a lesser extent Europe as a whole, during the mid-1660s.

    Known as the Great Plague of London, this iteration of the bubonic plague broke out in London in 1665 and spread so quickly that nearly 20% of the city’s inhabitants perished. That resulted in a city infrastructure unable to process bodies fast enough to contain the disease, resulting in mass graves around the city. By 1666, the plague’s progress had finally slowed.