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The History of Various Pandemics

For many Canadian youth, the COVID-19 pandemic is the first pandemic they have lived through or will remember living through, with direct consequences. However, there have been many more pandemics throughout history. Keep reading to learn what defines a pandemic and gain some quick knowledge on 5 past pandemics.


Pandemics, for the sake of this article, are defined by an unusually high outbreak of a new, infectious disease that spreads in humans across large regions.

Also in this article:

  • Infectious agent: What causes the disease.

  • Reservoir: Where the disease lives, grows and multiplies.

  • Vector: What carries and transmits the disease.

The Black Death or the Plague

The Plague was rampant in the mid 1300s and is still around today (but not considered a pandemic). Found in rats, the reservoir of the disease, the Plague was caused by a bacteria - an infectious agent dubbed Yersinia Pestis. The rats contracted fleas (the vector) then the fleas would infest humans and infect them with the plague. The Plague was bubonic (targeted lymph nodes), pneumonic (targeted lungs) and/or septicemic (targeted blood stream). If left untreated, this disease could kill in 3-7 days. The concept of quarantine originated in this century during the plague, coming from the 14th century Venetian word “quarantena”, meaning 40 days.


Cholera was caused by a water borne infectious agent called Vibrio cholerae. The reservoir for Cholera is humans - around 10% of those infected had severe symptoms from severe diarrhea to vomiting, leading to dehydration, shock and eventually, death. Cholera was thought to have originated from the Lower Ganges River, in India in 1817. There have been 7 cholera pandemics throughout history.


Smallpox was caused by infectious agents Variola Major and Variola Minor. Smallpox had an extremely high death rate of around 30%; yet, those who survived were left with severe scarring, deformities or blindness. This virus localized in the blood vessels of the skin, mouth and throat. Initially started as rashes, they would develop into painful, fluid filled blisters.

Smallpox is one of the only human diseases to have been completely eradicated (in 1980) through vaccinations. To control the spread of the disease, “variolation” was used: sores from smallpox were either scratched into the arm or inhaled through the nose. People would develop symptoms, but it would be nowhere near as severe as contracting the disease naturally from another person - after, they were then considered immune. This is the same model as live attenuated vaccines today, where a weakened version of viruses are injected into the body and memorized by memory B- and T-cells.

Spanish Flu

The Spanish Flu occurred during 1918, when there were no vaccines for flus. This virus infected ⅓ of the world’s population at the time, which was around 500 million people. The first wave was relatively neutral; simple fevers, aches and coughs were common. The second wave, however, was much worse. The infected's lungs filled with fluid, their skin turned blue and suffocation ensued. Usually, flus are not deadly, but the Spanish Flu was different. The virus had three specific genes that heavily weakened the respiratory system, from bonchi to lungs, and allowed bacterial pneumonia to take over. The pandemic only lasted a year, ending in the summer of 1919. Those who had it either recovered, acquiring natural immunity (which became herd immunity for some) or died.


Human immunodeficiency virus (HIV) can lead to the acquired immunodeficiency syndrome (AIDS). It spreads through bodily fluids (either through sexual intercourse or open wounds) or from mother to child.

  • Stage 1: The virus attaches itself to the T-cells of the immune system (those that are able to kill pathogens) and integrates itself into the DNA of those cells. This is Acute HIV Infection. People may feel flu-like symptoms.

  • Stage 2: It’s dormant and asymptomatic at this point (but can still be transmitted) and can stay this way for years with proper antiretroviral therapy medications. It is reproducing very slowly. This is Chronic HIV Infection.

  • Stage 3: The cells with viral DNA inside lyse (die), leaving the patient with an extremely weakened immune system. This is Acquired Immunodeficiency Syndrome (AIDS).

People do not die from AIDS. They die from sub-complications like the common cold, as their immune system is heavily compromised and unable to fight it off.

Resources and References

Denholm, D. (2020, April 17). Lessons from 4 other global pandemics throughout history.

Retrieved October 01, 2020, from https://medicalxpress.com/news/2020-04-lessons-


Government of the United States of America. (2012, May 18). Principles of Epidemiology.

Retrieved October 01, 2020, from https://www.cdc.gov/csels/dsepd/ss1978/


Government of the United States of America. (2016, August 30). History of Smallpox.

Retrieved October 01, 2020, from https://www.cdc.gov/smallpox/history/history.html

Government of the United States of America. (2018, May 11). General Information. Retrieved

October 01, 2020, from https://www.cdc.gov/cholera/general/index.html

Government of the United States of America. (2020, September 28). About HIV/AIDS.

Retrieved October 01, 2020, from https://www.cdc.gov/hiv/basics/whatishiv.html

History.com Editors. (2010, October 12). Spanish Flu. Retrieved October 01, 2020, from


History.com Editors. (2017, September 12). Cholera. Retrieved October 01, 2020, from


Morens, D., Folkers, G., & Fauci, A. (2009). What Is a Pandemic? The Journal of Infectious

Diseases, 200(7), 1018-1021. doi:10.1086/644537

Featured image courtesy of OHA 250: New Contributed Photographs Collection, Otis Historical Archives, National Museum of Health and Medicine.

Article Author: Linda Duong

Article Editors: Olivia Ye, Victoria Huang