4 Diseases That Impacted & Altered Human Existence

Humans may sit at the top of the food chain, but that doesn’t protect them from the specter of disease, which has disrupted the globe many times over.

Mar 10, 2024By Kassandre Dwyer, M.Ed History
diseases impacted human existence


Humans have developed technology to boost efficiency, build cutting-edge weaponry, and produce food for millions. However, while the global citizenry has made many strides in the medical field over the centuries, it has still often found itself powerless in the face of epidemics that have the potential to wipe out thousands, if not millions, of lives. Not only have these diseases changed the population, but they have also changed how those who remain live their lives, often in hopes that they can prevent something similar from happening.


1. Bubonic Plague

diseases changed history flea
Fleas are the primary vector of the Bubonic Plague. Source: Public Domain via Phys.org


Recognizable in name by virtually anyone who has taken a history class, the Bubonic Plague, or the “Black Death” as it is commonly known, was a bacterial disease that has swept parts of the globe many times over. Caused by a bacteria called Yersinia pestis, it was primarily transmitted by fleas transported on rats but can also be spread by other modes.


It has affected humans for centuries and still exists today, though it is relatively uncommon in most parts of the world. Archaeologists detected its presence in Bronze Age-era skeletons. The Justinian Plague, which started in the Mediterranean in 541 under the rule of the Byzantine Emperor Justinian and continued for approximately 200 years, was likely the Bubonic Plague. Historically, it was argued that the Justinian Plague was a contributing cause for the fall of the Roman Empire. However, while the epidemic was incredibly disruptive, killing thousands and requiring government intervention to help remove bodies from the city, modern study has largely debunked this theory.


doctor schnabel plague doctor
Doctors treating the plague in the Middle Ages were easily recognizable by their unique masks. Source: Wikimedia Commons


The most famous instance of the Bubonic Plague took place during the Middle Ages. After killing perhaps millions in Asia (there exist few complete or reliable records), the disease arrived in Sicily via sailors who had been in the Far East. After spreading through Italy in 1347, it quickly moved throughout the rest of Europe in the following years. With intermittent outbreaks over the next 400 years, the Black Death killed over a third of Europe’s population, or about 25 million people.

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The epidemic would radically change Europe’s economic and social standing. There was a shortage in the labor force and few skilled artisans. Crimes against Jewish people skyrocketed as some people blamed them for causing the plague via poisoning or other miasma. At least 235 Jewish communities went through mass persecution during the time of the Black Death epidemic of the Middle Ages. The drastic dive in population meant some communities had to rebuild from scratch, and the power structure in Europe changed, with the once-supreme Italy losing economic and political strength in the face of losing two-thirds of its population.


diseases changed history marmot
Marmots such as this one can transmit the plague. Source: CNN


Today, Bubonic Plague reservoirs include rodents such as groundhogs, prairie dogs, squirrels, marmots, and still, rats. Although antibiotics now exist that can effectively fight the infection, deaths from the plague are still seen, with Madagascar, the Congo, and Peru currently listed as the most endemic locations.


The Bubonic Plague can still cause economic disruption, such as in 2006 when over 150 workers at a diamond mine in the Congo contracted the plague, shutting down operations. Currently, most human cases in the United States occur on the West Coast and in the regions of New Mexico, Colorado, and Arizona. Symptoms include fever, headache, chills, and swollen lymph nodes called buboes (hence the name Bubonic).


2. Smallpox

diseases changed history smallpox pustules
Photo of Smallpox pustules, taken in Bangladesh, 1973. Source: KFF Health News


Smallpox can be blamed for killing off a large proportion of the Indigenous population of North America after being spread by European explorers and colonists. However, it had a massive impact on other areas of the world as well. Believed to have existed for over 3,000 years, smallpox is now considered eradicated by the Centers for Disease Control (CDC) and World Health Organization (WHO). Early symptoms of smallpox include a high fever, back pain, and fatigue. A few days later, the patient would develop a bumpy rash, beginning on the face and hands, with pustules filled with clear liquid. Eventually, the clear liquid turns to a pus, and the pustules dry and fall off. About 30% of smallpox victims died from their illness, and survivors were generally left with extensive scarring.


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Blankets infected with smallpox were used as biological weapons against America’s Indigenous peoples. Source: All That’s Interesting


Coupled with the flu and other European diseases, Smallpox aided in the destruction of approximately 95% of the native populations of the Americas within just a few years after the arrival of Europeans. Indigenous peoples had no immunity to these unfamiliar diseases, and they quickly took their toll on an unsuspecting population who had yet to understand germ theory, immunity, or disease prevention.


Though the Europeans didn’t intentionally spread smallpox, it nonetheless did unprecedented damage. In 1763, at the conclusion of the French and Indian War, the first recorded instance of intentional biological warfare took place in the future United States, when British soldiers distributed blankets contaminated with smallpox to the Shawnee and Delaware tribes during negotiations in an ongoing conflict known as Pontiac’s War.


smallpox vaccine boys
An iconic 1901 photo of 2 boys, one vaccinated against smallpox, right, and one not, after both were exposed to the virus. Source: The Jenner Trust


Smallpox was the first disease for which a successful vaccine was created in 1796. The last official case occurred in Somalia in 1977, though smallpox still exists in laboratories in case it is needed in the future for vaccination or as a defense against bioterrorism or biological warfare.


3. Spanish Flu

spanish flu victim
Members of the American Red Cross, wearing masks, remove a Spanish Flu casualty from a home in Missouri. St. Louis Dispatch Photo. Source: University of Maine


As World War I was in its final throes in 1918, many countries, including the United States and several in Europe, heavily controlled their media coverage due to the war. As a neutral party, Spain was not and ended up broadcasting heavily and truthfully on an influenza pandemic sweeping the globe. As a result, this disease got the moniker “The Spanish Flu.” It went by many other names as well, among soldiers and communities around the world: “the purple death,” “Flanders fever,” or “sand fly fever.” Despite its Spanish label, it is believed that the disease actually originated in the United States and was carried by troops leaving Fort Riley, Kansas, to the front in Europe, where it spread like wildfire.


diseases changed history camp funston
A Spanish Flu emergency hospital located at Camp Funston, Fort Riley, Kansas in 1918. Source: AP Photo via The Guardian


When it first erupted, the disease acted like a typical flu, challenging for some compromised individuals but not a huge health concern. However, when it resurfaced later in 1918, it went on a deadly rampage. By the time the epidemic wrapped up, it had killed an estimated fifty million people worldwide.


The virus would start with typical flu symptoms: a sore throat, cough, and chills. However, within days, it would begin to severely attack the lungs. It killed patients due to severe respiratory failure, essentially hardening the lungs and drowning the sick in their own fluids. Those in which the illness had progressed would start showing blue-black skin tone, often beginning on the feet, a symptom of hypoxia, or lack of oxygen (hence the name “purple death”).


diseases changed history virus dna
Changing DNA allows viruses to recur successfully. Source: Forbes


The twist with this disease is that it had the potential to strike anyone down, not just the very old, very young, or infirm. Healthy, strapping soldiers were brought to their deathbeds in a matter of days or sometimes even hours. No one seemed safe from the illness. Scientists rushed to create a vaccine for this looming virus as it spread to both rural and urban areas worldwide.


Even remote areas weren’t safe. Islands found themselves hit with the disease, and some villages in Alaska were wiped out entirely as a result of the epidemic. Life came to a standstill in some areas, with businesses and schools closing all over, some willingly, some by city order. People wore face masks, and police in some areas were ordered to arrest those who coughed or sneezed in public. Many families struggled to survive due to a lack of resources or the death of a breadwinner.


pandemic influenza flyer
A flyer posted at the US Treasury Department providing instructions on public behavior in order to prevent the spread of the Spanish Flu. Source: Library of Congress


Adding to the chaos was the strain on the medical community. Many doctors and nurses were on the front working in war hospitals and, therefore, unavailable to help the sick on the homefront. Others became sick themselves from helping the ill. This increased the pressure to find a vaccine, and pharmaceutical companies worked around the clock to find the solution. However, before the antigen could even be isolated, it seemed to disappear from the global stage, affecting over one-fifth of the global population on its rampage.


4. COVID-19

A rendering of a COVID-19 molecule. Source: Drexel News


The novel human coronavirus 2019, known familiarly as COVID-19 or simply COVID, is all too fresh in many minds. However, due to mass media (and social media) coverage, a great deal of misinformation exists about the disease and its biology. True to its name, the illness was first identified in 2019 in the city of Wuhan in China. Pneumonia-like in form, the disease didn’t respond to typical treatments, and soon doctors and virologists noticed that it was a unique pathogen, and a worldwide response began as it started to spread rapidly. The first confirmed case outside of China occurred in Thailand in early January 2020 and was detected in several other countries, including the United States, by the end of the month.


photograph landscape wuhan
The city of Wuhan. Source: Phongsaya Limpakhom via The Guardian


Multiple countries declared a state of emergency as a result of the COVID-19 pandemic, with one million deaths occurring worldwide by the end of September 2020. A number of shutdowns, quarantines, and lockdowns were put into place in different cities and countries around the world in an effort to control the pandemic, causing a great deal of political strife and social controversy.


The first COVID-19 vaccines were administered in December 2020. Like other viruses, the organism that causes COVID-19 can mutate, and variants have infected the public since the initial outbreak. Vaccines have attempted to keep up with the variants, but COVID remains a worldwide public health risk to this day.


covid 19 masking
People around the world have been affected by COVID-19. Source: International Committee of the Red Cross


The COVID-19 pandemic changed the way that the people of the world interact with one another. Automation has increased around the world in order to reduce the chances of exposure to shared germs. The animosity that the political divisions created during the pandemic brought to a head still exists in many places, leaving global citizens largely suspicious of one another.

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By Kassandre DwyerM.Ed HistoryKassie is a farmer with a passion for history who has a day job teaching middle school social studies in her hometown. In addition to earning NBCT certification and M.Ed. in History, she holds an M.Ed in Curriculum & Instruction and a B.S. in Sustainable Agriculture/Animal Science. She is particularly interested in telling the stories of often overlooked historical perspectives or hidden truths, and is especially intrigued by the history of America’s Indigenous peoples, war, and the “wild west.”