How Penicillin Changed Medicine Forever

 By Steve Johnson

Throughout history, diseases have shaped the world in ways we can hardly imagine. They have changed the course of empires, wiped out millions of people, and forced humans to find new ways to survive and fight back.

These diseases remind us of how fragile life can be, but they also show us the power of human courage, science, and hope. Let’s take a journey through time to learn about the seven most devastating diseases in history and how they changed the world.

1. The Black Death (Bubonic Plague)

When: 1347–1351
Where: Europe, Asia, and Africa

The Black Death was one of the deadliest diseases in history. It spread like wildfire across Europe, Asia, and Africa, killing an estimated 75 to 200 million people. That’s almost half of Europe’s population at the time! The disease was caused by bacteria carried by fleas that lived on rats. When the rats traveled on ships, the fleas spread the disease to humans.

People who got sick had painful symptoms like fever, chills, and swollen lumps called "buboes." Most people died within days of getting sick. The Black Death caused so much fear that people didn’t know what to do. Some thought it was a punishment from God, while others blamed their neighbors.

But the Black Death also led to some positive changes. After the disease, there were fewer workers, so those who survived could demand better pay and rights. This helped end the feudal system, where poor people worked for rich landowners. The Black Death taught us how important it is to understand diseases and find ways to stop them.

2. Smallpox

When: For thousands of years, until 1980
Where: Worldwide

Smallpox was a terrifying disease that killed millions of people for thousands of years. It caused fever, rashes, and painful blisters all over the body. Many people who survived were left blind or with deep scars. Smallpox was so deadly that it wiped out entire communities, especially among Native Americans when European settlers brought the disease to the Americas.

But smallpox also has a story of hope. In 1796, a doctor named Edward Jenner discovered the first vaccine. He noticed that milkmaids who got cowpox, a milder disease, didn’t get smallpox. He used cowpox to create a vaccine that protected people from smallpox. This was the beginning of modern vaccines!

Thanks to global vaccination efforts, smallpox was completely wiped out by 1980. It’s the only human disease to have been eradicated. Smallpox shows us that even the worst diseases can be defeated with science and teamwork.

3. The Spanish Flu

When: 1918–1919
Where: Worldwide

The Spanish Flu was one of the deadliest pandemics in history. It infected about one-third of the world’s population and killed an estimated 50 million people. Unlike most flu viruses, which mainly affect the very young and old, the Spanish Flu was especially deadly for young, healthy adults.

The disease spread quickly during World War I, as soldiers traveled across the world. It got its name because Spain was one of the first countries to report the outbreak, but it likely started elsewhere. The Spanish Flu caused high fever, coughing, and severe pneumonia. Many people died within days of getting sick.

The Spanish Flu taught us the importance of public health measures like wearing masks, washing hands, and staying apart to stop the spread of disease. It also showed how important it is to share information about outbreaks quickly, so the world can work together to fight them.

4. Malaria

When: Thousands of years, still a problem today
Where: Tropical and subtropical regions

Malaria is a disease caused by parasites that are spread by mosquitoes. It has been around for thousands of years and still affects millions of people today, especially in Africa. Malaria causes fever, chills, and flu-like symptoms. If not treated, it can be deadly.

Malaria has had a huge impact on history. It slowed down European colonization of Africa because many explorers and soldiers died from the disease. During World War II, scientists developed medicines to fight malaria, which helped soldiers survive in tropical regions.

Today, we have better tools to fight malaria, like mosquito nets, insecticides, and medicines. But it’s still a major problem in many poor countries. Malaria reminds us that diseases often hit the poorest people the hardest, and we need to keep working to help everyone.

5. Tuberculosis (TB)

When: Thousands of years, still a problem today
Where: Worldwide

Tuberculosis, or TB, is a disease that attacks the lungs. It spreads through the air when someone coughs or sneezes. TB has been around for thousands of years and has killed millions of people. In the 1800s and early 1900s, TB was one of the leading causes of death in Europe and America.

People with TB often had a terrible cough, lost weight, and became very weak. Before antibiotics were discovered, there was no cure for TB. Many people went to special hospitals called sanatoriums, where they rested and breathed fresh air in the hope of getting better.

In the 1940s, scientists discovered antibiotics that could cure TB. This was a huge breakthrough, but TB is still a problem today, especially in poor countries and among people with weak immune systems. TB teaches us that even when we find cures, we must stay alert and keep fighting diseases.

6. HIV/AIDS

When: 1980s–present
Where: Worldwide

HIV/AIDS is a disease caused by a virus that attacks the immune system. It first appeared in the 1980s and quickly became a global crisis. Millions of people died because there was no cure, and many others were treated unfairly because of fear and misunderstanding.

HIV spreads through blood, sexual contact, and from mother to child during birth or breastfeeding. In the early days, people with HIV/AIDS faced a lot of stigma and discrimination. But brave activists and scientists worked hard to raise awareness and find treatments.

Today, we have medicines that can control HIV and allow people to live long, healthy lives. We’ve also made progress in preventing the spread of HIV through education and testing. HIV/AIDS shows us the importance of compassion, science, and never giving up.

7. Cholera

When: 1800s–present
Where: Worldwide, especially in areas with poor sanitation

Cholera is a deadly disease caused by bacteria that spread through contaminated water and food. It causes severe diarrhea and dehydration, and without treatment, it can kill within hours. Cholera has caused many pandemics throughout history, especially in the 1800s when it spread from India to Europe, Asia, and the Americas.

One of the worst cholera outbreaks happened in London in 1854. A doctor named John Snow discovered that the disease was spreading through a contaminated water pump. His work helped people understand that clean water and sanitation are essential to preventing cholera.

Today, cholera is still a problem in places with poor sanitation and limited access to clean water. But we have treatments like oral rehydration salts and vaccines to help prevent and treat the disease. Cholera reminds us of the importance of clean water, good hygiene, and public health systems.

Lessons from History

These seven diseases have caused immense suffering, but they have also taught us important lessons. They show us how powerful nature can be and how vulnerable we are as humans. But they also show us the strength of the human spirit.

Throughout history, people have faced diseases with courage and determination. Scientists have discovered cures, doctors have cared for the sick, and communities have come together to support one another. Each disease has pushed us to learn more, invent new tools, and find better ways to protect ourselves.

These stories remind us that even in the darkest times, there is hope. By learning from the past, we can build a healthier, safer future for everyone. Let’s remember the lessons of these devastating diseases and continue to fight for a world where no one has to suffer from preventable illnesses. Together, we can overcome anything.