Four of the deadliest epidemics & pandemics
Introduction
BARBARA SPIECKER:
Bacteria and viruses have been around longer than humans have been.
(Image of bacteria and virus)
For as long as humans have been around, epidemics and pandemics have happened throughout the years.
These bacteria and viruses are two types of infectious agents that have killed more people than other pathogens.
(Image of bacteria and virus)
These diseases and outbreaks have the ability to change the course of history.
However, all pandemics have something in common, a gradual reduction in death rates due to improvements in healthcare and greater understanding of the science behind bacteria and viruses.
Let’s take a brief look at 4 of the deadliest pandemics.
Black Death (Bubonic Plague)
ALICIA WOOTEN:
When you think of the plague, you are probably thinking of the epidemic of bubonic plague in the mid 1300s.
(Image from the Middle Ages of a mass burial)
This disease was caused by a bacteria called Yersinia pestis.
(Image of Yersinia pestis)
The bacteria originally was in rats then in fleas. These fleas would bite humans and pass the bacteria.
(Image of flea)
It originated in Mongolia and spread to Europe through trade routes.
Those who got sick would develop flu-like symptoms and their lymph nodes would swell up in the area where the bacteria entered the body. This was often in the armpits, neck, or groin area.
(Image of person with swollen lymph nodes on thigh area)
These swollen lymph nodes would become black and that was why people called it the black death.
The plague killed about 30-50% of the European population or about 50 million people.
(Image of skeletons in a mass grave)
It is not known how or why it ended, but many people believe the implementation of non pharmaceutical interventions and public health measures such as quarantines, personal hygiene, use of disinfectants helped slow the pandemic. However, the bubonic plague continued to occur in smaller outbreaks over the years. This disease is still around today.
From 2010 to 2015, over 3000 cases have occurred and almost 600 deaths.
Smallpox
SPIECKER:
One of the highest death tolls after the Bubonic Plague is smallpox with 56 million deaths.
(Image of a Columbia-era drawing of a smallpox victim on bed)
Smallpox was instrumental in the fall of the Aztec and Inca empires in the Americas.
It is also the only human disease to have been eradicated by vaccination.
(Image of smallpox)
The origin of smallpox remains lost in history and the first credible evidence appeared in the mummified remains of the Egyptian pharaoh Ramses V in 1142 B.C.
(image of Ramses V’s mummy)
Smallpox caused fluid-filled pustules to develop and expand, in some cases joining together and covering large areas of skin.
Then, these pustules will become scabs and fall off the skin.
(Image of man with smallpox scabs on face)
The disease was spread by close contact with the sores or respiratory droplets of an infected person. Contaminated bedding or clothing could also spread the disease. A patient will remain infectious until the last scab separated from the skin.
Somehow milkmaids were immune to this disfiguring disease and it was suggested that they contracted a milder and similar disease from cows,
called cowpox.
(Image of cowpox)
Those who contracted cowpox gave them protection from smallpox.
Many farmers and scientists suspected this, but it wasn’t until the late 1700’s that Edward Jenner’s
(Image of Edward Jenner)
work showed the first scientific evidence of giving cowpox pus to people could prevent smallpox.
(Image of Jenner giving a vaccine to his son)
This technique began the idea of vaccines using attenuated (weaker) pathogens to allow the body to develop immunity against similar severe pathogens.
There were intensive smallpox vaccination campaigns in the 1960s and 1970s.
(Image of smallpox vaccine)
In the 1980, the World Health Organization announced smallpox eradicated from the world.
Spanish Flu
WOOTEN:
The number of deaths from smallpox is similar to the 1918 Spanish Flu.
(Image of a large room with many hospital beds, patients, and healthcare staff)
From 1918 to 1919, at least 10% of the population died. Despite the name, this flu did not originate in Spain. Geographic origins are unclear, but genetic analysis suggests that the influenza H1N1 virus came from birds.
(Image of H1N1 virus)
During the final months of World War I, soldiers were living in dirty and wet conditions. They were also malnourished so their immune system was weakened. Many soldiers became ill with the flu.
(Image of healthcare workers carrying a patient on a gurney)
As soldiers began to return home all over the world, they brought the virus with them. About 500 million people in the world became infected and about 50 million died worldwide.
(Image of a row of beds with sick patients)
These deaths came in three waves, with the second wave causing the most deaths.
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There are three groups: children, young healthy people and older people. The common flu typically killed children and older people. But the Spanish Flu pandemic was unique because people from all three age groups died.
(Image of police officers wearing masks)
Because there was no vaccine against influenza yet, people had to practice non-pharmaceutical interventions like during the bubonic plague. Those who contracted the flu could develop pneumonia overnight and be dead the next day. This pandemic lasted for 2 years until those who were infected died or developed immunity. It wasn’t until several decades later that a vaccine was developed in 1938.
(Image of H1N1 virus)
Today we still see the H1N1 virus, but they are genetically different from the Spanish Flu virus.
HIV/AIDS
SPIECKER:
The 4th largest pandemic is HIV/AIDS and it is one of the global pandemics that we are currently battling. To date, 25-35 million people have died.
(Image of HIV virus attacking)
HIV is short for Human Immunodeficiency Virus and the origins of it likely came from primates
(Image of primates)
who were infected with the Simian Immunodeficiency Virus (SIV). SIV is a virus that attacks the immune system of primates.
(Image of SIV virus)
How did SIV enter the human body? When SIV-infected primates were hunted for their meat, the SIV virus entered the human host through eating or cuts or wounds. Then, on a rare incidence, SIV successfully adapted itself within the new human host and became HIV. The first transmission of SIV to HIV in humans led to the emergence of a pandemic that started in Democratic Republic of Congo in 1920.
(Image of DRC on a map)
HIV can also be transmitted from person to person through bodily fluids such as blood, semen, vaginal fluids, anal fluids, and breast milk. The virus, HIV, attacks the human immune system and weakens the body’s ability to fight infections and diseases. During the early stages of HIV, it is often asymptomatic and without treatment, the virus will kill your immune cells to the point where your body cannot produce enough immune cells to fight off a pathogen.
(Image of HIV virus attacking)
When the number of immune cells drop below a certain threshold, you will develop a disease called Acquired Immunodeficiency Syndrome (AIDS).
Conclusion:
WOOTEN:
We just discussed four major pandemics and you might have noticed that the number of deaths were very high. These numbers may be explained by varying degrees of medical knowledge and advancements during the different eras.
(Image of a healthcare worker)
However, even with strong modern public health measures and scientific knowledge, we are not completely immune. New strains of bacteria and viruses continue to evolve with us and new challenges will be encountered. As always, we will find ways to battle the pathogens we encounter.
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