Causes of illness and disease

Miasma Theory: People believed that illness was caused by ‘bad air’ or miasmas. This faith in the miasma theory often led to ineffective treatments such as burning incense.
Religious Beliefs: Diseases were often seen as punishment from God for sins. Medicinal solutions typically included prayer, leading to the founding of many hospitals by monastic orders.
Astrology and the Four Humours: A popular theory, dating back to the Greeks, held that a body’s health was connected to the balance of four body fluids or ‘humours’. Illness was thought to result from imbalances in humours, and influenced by the positioning of the stars (astrology).

Continued beliefs in Miasma and Four Humours: Both theories remained prevalent during Renaissance, though there was increasing criticism.
New Understanding: The use of human dissection during the Renaissance led to better understanding of human anatomy and how disease affected the body.

Germ Theory: Louis Pasteur and Robert Koch’s work led to the formulation of the Germ Theory in the 19th century. Diseases were understood to be caused by specific kinds of ‘germs’ or microorganisms.
Living Conditions: Rapid industrialisation and urbanisation led to overcrowded housing and poor sanitation, leading to rapid spread of diseases like cholera and TB.

Continued Germ Theory: The trend of attributing diseases to specific microorganisms continued into the 20th century and remains the guiding theory to date.
Lifestyle Factors: In recent years, there has been growing awareness of how lifestyle factors, such as diet, exercise, smoking and alcohol can contribute to diseases like heart disease, obesity, and cancer.
Genetics and Epigenetics: Research has shown some diseases have a genetic component, with predisposition to certain illnesses being inherited. Epigenetic research also explores the impact of environmental factors on gene expression, leading to disease.

In each period, the prevailing understanding of illness and disease was based on the state of scientific knowledge and the broader cultural views of the time.
Over time, there has been a shift from viewing disease as a divine punishment or natural imbalance, towards recognising its biological and environmental causes.
This understanding of changes in health and medicine throughout history is crucial to understand our current methods of diagnosing and treating disease.