How Our Understanding of Disease has Evolved: A Comprehensive Exploration of the History and Development of the Concept"

How the concept of disease came about

What is the disease? Simply put, the opposite of normal health is what we call disease. But defining disease is not an easy task. The concept of disease is very broad. A disease has different stages. Each disease presents with varying symptoms ranging from mild illness to life threatening. Again, even after germs enter the body, no symptoms may appear for a certain period of time - this condition is called 'dormancy'. Sometimes multiple germs act as the cause of a disease. Therefore, it is very difficult to define the disease. That is why the World Health Organization has defined health but has not been able to give a clear definition of disease.

This complexity of the concept of disease has been bothering people since ancient times. Once upon a time people started thinking of evil energy as the cause of disease. God's curse, certain body fluids, polluted air - these were considered causes of disease. Even then the idea of ​​germs did not come to human imagination. Later, when the idea of ​​germs came forward, it was seen that not only germs, but also other factors act as the cause behind a disease. Thus, in the evolution of time, various theories have emerged in the concept of disease.

Emergence of evil forces

Religion, philosophy and medicine were three of the most important early human civilizations. This has therefore had a clear impact on the concept of disease. Many believed that evil energy directly enters the body and causes illness. Others considered disease to be the result of human evil deeds. They accepted these diseases as a punishment from the creator.

Thus, around 5000 BC, people's ideas about disease were mixed with superstition, religion, magic and the touch of evil forces. These are called supernatural theories of disease.

Theory of humor

The Greeks could not accept this supernatural theory of disease. Rather, famous people like Hippocrates, Galen wanted to explain the disease in a natural way. Their idea was that there is a close relationship between the human body and the environment of earth, air, fire and water. These elements of environment have characteristics of cold, dry, hot and humid respectively. And these characteristics are represented by four types of body fluids (humor) - phlegm, yellow bile, blood and black bile.

Their assumption was that the balance of these four types of fluids in the body is to be healthy. And if there is inconsistency between these four fluids, the disease will take root in the body. Illnesses are caused due to excess of blood in the body - if it seems that some of the blood would be removed from the body and tried to balance it! Although the theory of humor was largely unscientific, such concepts were prevalent in India, China, and Egypt, similar to the Greeks.

Miasma theory

Later miasma theory emerged as the cause of disease. Here, in the low-lying swamps, a kind of vapor created by the decay of organic matter was seen as a cause of disease. The invisible, untouchable vapor was called 'Miasm'. Prior to the discovery of the germ theory in the 1880s, this miasma theory was a widespread misconception. Back then, mosquito-borne diseases like malaria were thought to be spread through polluted air. The word 'Malaria' is originally an Italian word meaning 'polluted air'.

This polluted air was even blamed for plague epidemics. Doctors used strange masks to avoid the stench when treating plague patients. The mask was filled with flowers, leaves, and honey! In history they are known as plague doctors. Cholera was once seen as a result of this polluted air. Around 1850, John Snow showed that cholera was spread not by air, but by contaminated water.

 

Transmission theory

Along with the humor and miasma theory, there was another concept of disease that spread from person to person like smallpox. Italian physician Fracastro played a special role in establishing this theory. But since the invention of the microscope, no strong evidence for such transmission could be produced.

germ theory

The germ theory is regarded as a blessing in the history of medical science. Because, to treat a disease, it is necessary to know its cause first. Germ theory says that there is a specific germ behind every disease. It can be any germ including bacteria, viruses, fungi. Louis Pasteur and Robert Koch played the most important role in establishing the germ theory of disease. After 1860, the germs of anthrax, tuberculosis, cholera, diphtheria etc. were discovered one by one. This is a golden age of microbiology. And identifying the cause of the disease is half the work of discovering its treatment method! At that time, the invention of drugs and vaccines one after another made unimaginable progress in medicine.

Triangular relationship between microbe, person and environment

Although the discovery of the germ theory introduced the concept of disease into the modern era, it has some limitations. For example: Tuberculosis is caused by the germ of tuberculosis, but not everyone who comes in contact with this germ gets tuberculosis. Because, in addition to the agent, the host and the environment play an important role. Malnutrition, environmental pollution, drug addiction, poverty etc. act as one of the factors affecting the incidence of tuberculosis. This triangular relationship of microbe, person and environment is the epidemiological triad. Later, however, the researchers opined that time also plays a role here.

Multifactorial causes of disease

Many diseases can be cured thanks to the blessings of vaccines, antibiotics and drugs, thanks to the germ theory. But 'modern' diseases such as cancer, coronary heart disease, mental illness, etc., which are not caused by any specific germ, crop up. Sydenham was the first to recognize the importance of multifactorial factors as a cause of disease. Apart from germs, genetic and nutritional factors, metabolic, psychological factors also come up behind a disease. For example: high fat diet, obesity, smoking, lack of physical activity etc. act as causes of coronary heart disease.

Cause of disease

McMahan and Pough put forward a concept - Web of Causation to describe diseases that do not have a specific cause but are influenced by multifactorial factors over a long period of time. Investigating the causes of chronic diseases reveals that many factors are related to each other, like a web.

For example: excessive fatty food intake, obesity, smoking etc. contribute to myocardial infarction or heart attack. These issues are again very closely related to each other. Just as obesity alone can be a trigger for heart attacks from overeating, obesity can also cause high blood pressure from heart attacks. Just as anxiety can lead to a heart attack in a chronic smoker, anxiety can cause high blood pressure to lead to a heart attack. Such interrelationship of the causes of disease plays a great role in the development of its treatment methods. By creating obstacles at various stages of interrelationships, one can get rid of the disease.

Over time, new ideas are added to the study of diseases. A clear understanding of a disease is the main tool for developing its treatment. Unprecedented advances in medicine have been made in the past and continue to be made using these tools.