“The joy I felt at the prospect before me of being the instrument destined to take away from the world one of its greatest calamities was so excessive that sometimes I found myself in a kind of reverie.”

–  Edward Jenner, on smallpox vaccines

INTRODUCTION

March 11th, 2022 marks two years since COVID-19 was declared a pandemic by the World Health Organization. For many, this grim milestone may evoke feelings of despair, grief, and hopelessness as we all grapple with the reality of life post-virus. But we can also take some solace in knowing that humans have faced and survived this challenge before.

A global pandemic, novel as it may seem to us, is nothing new to history. From the Black Death of the 14th century to the HIV/AIDS crisis of the 80s and 90s, infectious diseases have ravaged humanity since the dawn of time. These crises brought with them immense pain and suffering – but also taught us how to be more prepared for future  pandemics.

Today’s blog post will reflect upon five of history’s most notorious pandemic diseases and the lessons that helped us navigate COVID-19:

• Plague
• Smallpox
• Cholera
• Influenza
• HIV/AIDS

Plague

Plague is one of history’s most notorious pandemic diseases. It is caused by the bacterium Yersinia pestis, which is typically transmitted to humans via the bites of infected rodent fleas (Centers for Disease Control and Prevention, 2021). The three basic types of plague are bubonic, septicemic, and pneumonic (Healthline, 2022).

There have been three major plague pandemics in recorded history. The first was the Justinian plague of 541 CE which spread across Africa, Europe, Asia, and the Middle East, killing an estimated 30 to 50 million people (Roos, 2021). The second was the infamous “Black Death” of Europe from 1347-1352, which killed more than a quarter of the European population (Frith, 2012). The third began in 1894 and circulated around the world until 1959, causing more than 15 million deaths (Frith, 2012). 

Today, plague can be effectively treated using antibiotics. Between 2010 and 2015, there were just 3248 reported cases and 584 deaths worldwide (World Health Organization, 2017).

Smallpox

Named for the cratered pockmarks or “pox” it left on the skin, smallpox was once one of the world’s most deadly pathogens (Roos, 2021). Historians link the spread of this disease to the expansion of global trade routes and exploration. European settlers infamously brought the disease to the Americas in the 16th century, killing roughly 90-95 percent of the continent’s Indigenous population over the course of a century (Roos, 2021). 

One of the first treatment options for smallpox was variolation, a practice wherein dried pus from a smallpox blister was blown up the nose of a patient to confer immunity (Flemming, 2020). In the late 18th century, British physician Edward Jenner created the first smallpox vaccine after realizing that dairy maids who had been infected by cowpox – a much milder virus – appeared to be immune to smallpox (Roos, 2021). 

Jenner’s vaccine would go on to save the lives of millions over the course of the 19th and 20th centuries. On May 8th, 1980, following a lengthy campaign by the WHO, the world was declared free of smallpox (Centers for Disease Control and Prevention, 2021). To this day, it is the only disease that has been completely eradicated worldwide.

Cholera

Cholera is an acute diarrheal infection caused by ingesting food or water contaminated by the bacterium Vibrio cholerae (World Health Organization, 2021). The disease is believed to have originated in the Ganges delta in India and spread across the world over the course of the 19th century (World Health Organization, 2021).

Seven major cholera pandemics have been recorded in recent history. The third cholera pandemic from 1852-1859 proved the deadliest, spreading across Europe, Africa, and North America. In 1854, the disease killed 23 000 people in Great Britain alone (History, 2020). That same year, famed British physician John Snow discovered that London’s cholera outbreak was linked to a contaminated communal water pump, marking a huge breakthrough in cholera prevention and solidifying Snow as one of history’s most influential figures in public health and epidemiology (History, 2020). 

Today, cholera is practically unheard of in most high-income countries. It can be easily prevented by investing in high-quality clean water and sanitation infrastructure – however, many low-income countries do not have access to these critical resources. As a result, as many as 143 000 people still die from the disease every year (World Health Organization, 2021). 

Influenza

Influenza is a common but highly infectious virus that circulates seasonally in most countries. Occasionally, a new strain of influenza may emerge and spread among a population, which can escalate to pandemic levels if not contained (History, 2018). 

The 20th century saw three major influenza pandemics. The deadliest and most well-known was the so-called “Spanish Flu” that tore across the globe in 1918-1919 following the end of World War I. This pandemic is estimated to have infected around a third of the world’s population, killing 50 million people in total (Centers for Disease Control and Prevention, 2018). 

Today, seasonal influenza can be largely controlled through annual flu vaccinations and managed through symptomatic care at home. However, it can still be lethal for vulnerable groups including young children, the elderly, pregnant women, and people with chronic diseases (History, 2018). In 2017, the WHO estimated that as many as 650 000 people die of a respiratory disease linked to seasonal flu each year. 

HIV/AIDS

First detected in the early 1980s, human-immunodeficiency virus (HIV) and its associated condition, acquired immunodeficiency syndrome (AIDS), is one of the most devastating modern diseases. Scientists believe the virus originated in West African chimpanzees in the 1930s and slowly spread across the globe over the following decades (Canadian Foundation for AIDS Research, n.d.). In 2020, an estimated 37.7 million people were living with HIV, the majority of whom were located in Africa (World Health Organization, 2021). 

In 1981, doctors reported an unusual increase in rare forms of pneumonia and cancer in young gay men living in the United States (Canadian Foundation for AIDS Research, n.d.). The disease was originally labeled as gay-related immune deficiency (GRID), but was soon re-named to AIDS once it became clear that many invidiuals of differing sexual orientations were being infected (Canadian Foundation for AIDS Research, n.d.). The LGBTQ+ community, however, continues to face widespread stigma and discrimination as a result of this early association. 

Since the pandemic began, more than 36 million people have died of complications related to HIV/AIDS (Cichocki, 2021). Today, the disease is no longer an automatic death sentence as it can now be effectively managed using antiretroviral therapy (ART) (World Health Organization, 2021). Global access to ART, however, is far from equitable, leaving many in low-income regions at a higher risk of disease progression. 

COVID-19: a pandemic for modern times

As is now well documented, SARS-CoV-2 (the virus that causes COVID-19) was first detected in Wuhan, China in December 2021. At the time of this writing, the virus has generated more than 448 million reported cases and killed more than six million people worldwide (World Health Organization, 2022).

Though still ongoing, the COVID-19 pandemic has revealed some important truths about public health and broader society – many of which we have known for decades. 

Globalization and international exchange, for all its benefits, also increases the likelihood of a disease elevating to pandemic status. This fact is well reflected in the history of global pandemics, but global policy strategies made to address it contain considerable gaps. The current crisis has highlighted the need for greater investment in disease surveillance, pandemic prevention, and healthcare capacity building, as well as a need to incentivize global data sharing and transparency.

Additionally, individuals from low-income and marginalized backgrounds have suffered disproportionately from the effects of COVID-19 due to various racial, social, and economic factors. This reality is also not unique to the current pandemic – since the days of the Black Death, society’s poorest and most vulnerable have always borne the greatest losses when sickness rolls around. Despite this, we have allowed the pattern to continue during COVID-19, leaving essential workers without sick pay and the world’s poorest countries without access to life-saving vaccines. These inequities must be rectified.

This pandemic needs to serve as a wake-up call to governments the world over. We know these are the outcomes of a pandemic – we’ve seen it time and again. And yet, we somehow find ourselves having to learn the same lessons over and over. COVID-19 may be the most recent pandemic, but it certainly will not be the last – for all of our sakes, let’s remember what we’ve learned for next time.