Topic 4.2
Why is understanding the history of infectious diseases important?
Infectious diseases have shaped human history, influencing societies and prompting critical scientific discoveries. By exploring the journey from myths to modern science, we gain insights into how far our understanding of diseases and their prevention has come.
Infectious Diseases in History
An infectious disease, also known as a contagious disease, occurs when a pathogen enters a host and begins to reproduce, releasing toxins that cause illness. People first started realising that diseases could be spread from person to person during the Renaissance.
By 1723, scientists had developed working microscopes. Even after microscopes were invented and microorganisms were discovered, scientists still didn’t believe that they were the cause of the disease. It was like convincing the scientists that an ant could kill an elephant.
Debunking Myths of the Past
Below are beliefs about diseases from history. Some are myths, and some are facts. Your task is to:
1. Decide which are “Facts” and “Fiction”. Once you’ve decided, flip the cards to get the answer.
2. Choose one belief that you found surprising or interesting. Explore this further and share with others what you find.
3. Optional Reflection: Why do you think some of these myths lasted so long, and what changed people’s understanding over time?
Diseases are caused by bad smells (miasma)
Diseases are caused by microorganisms like bacteria, viruses and fungi, not smells. The miasma theory was disproven when scientists discovered that germs, not odours, spread disease.
Illnesses are punishments from the gods
Illnesses are caused by biological factors like infections, genetics, and environmental exposures, not divine punishment. This belief stemmed from a lack of scientific knowledge in ancient times.
Invisible creatures spread disease
This is true! Microorganisms like bacteria and viruses, invisible to the naked eye, are responsible for many diseases. This was proven after the invention of microscopes and germ theory.
An imbalance of the four humours (blood, phlegm, yellow bile, black bile) causes disease
The four humours theory, popular in ancient medicine, was replaced by modern medical understanding. Pathogens, genetics and other factors cause diseases, not humoral imbalances.
Carrying flowers or herbs protects you from disease
While flowers and herbs may smell pleasant, they do not protect against disease. This practice arose during plagues when people believed bad smells caused illness (miasma theory).
Disease can spread by looking at a sick person (evil eye)
Diseases are not transmitted by sight. They spread through pathogens like bacteria and viruses via contact, droplets or vectors like insects.
Only poor hygiene causes disease
Poor hygiene can increase the risk of infection, but diseases can also spread through contaminated food, water, insect bites and contact with infected individuals or animals.
Bloodletting can cure illnesses
Bloodletting was a common historical practice based on humoral theory, but it is ineffective for most illnesses and can harm the patient. Modern medicine relies on evidence-based treatment.