History of Public Health

Introduction

Methods of preventing disease go back many centuries. Concepts of disease were crude and often based on anecdote. Some recommendations and practices were ineffective, if not even harmful to health such as bloodletting.

In the mid-1800's there was a hygiene movement, particularly in the UK, with focus of improvements of cleanness and well-being of the poor. Additionally, at the end of the 19th century germ theory became accepted.

There are 4 outcomes to take from this course:

1. Explain the evolution of concepts about cause and prevention of disease
2. Understand the importance of studying the factors associated with outcomes in a systematic way in human populations.
3. Discuss some of the major historical figures and events that played a role in evolution of public health and epidemiology
4. Describe the overall structure of the public health system in the US today

Early Concepts of Disease

10,000 years ago when humans were hunter-gatherers and lived in small, nomadic groups accumulating waste and contamination wasn't a problem. Early concepts of disease revolved around superstition, myths and religion (bad spirits, Pandora's box, etc).

The agricultural revolution provided more secure supply of food and enable expansion of population. People often lived off one or two crops, often lacking protein and vitamins. The domesticated animals provided food and labor, but also carried diseases that could be transmitted to humans. Waste accumulation attracted rodents and insect vectors and with people living in larger groups there was a greater opportunity for transmission of diseases.

The first concept of disease not founded on superstition was the Hippocratic corpus; A Greek concept that disease is caused by an unbalance of the environment or natural forces, and Blood, Bile, Phlegm, and Melancholy must be kept equal within the body. Although the concept clearly incorrect by today's medical standards, Greek doctors would prescribe changes in diet and lifestyle. It also became the rational for bloodletting, which continued for many centuries despite lack of evidence.

The Bubonic Plague

The bubonic plague caused by a bacteria that lives in the intestines of fleas. Fleas were the vector and rats were a reservoir for the bacteria that could easily transmit the disease. Occasionally, an infected flea could jump to a human and infect them directly. Causing dark, tender, swollen nodules. Symptoms also included headache, and delirium and was fatal in about 60% of cases.

Starting in 1347 Europe experienced waves of the plague which lasted until the late 1700's. It was believed to have originated in Asia and traveled along trade routes to the black sea.

The most popular explanation was that it was caused by miasmas - invisible vapors which emanated from swamps or cesspools and floated around in the air where they could be inhaled. One pope kept fires burning on both sides of the room to counter miasmas. Plague doctors kept herbs and flowers in a beak-like mask to ward of miasmas. Of course these were all ineffective as it was spread by flea bites. In a sense the real cause of transmission was population density and waste stagnation, which attracted rats with the fleas that carried the plague. Later the pneumonic form of the plague caused people to cough up blood and could spread by inhalation.

One might blame the lack of preventative measures and knowledge about transmission on the primitive understanding of medicine, however this wasn't due to a lack of technology but the fact that humans had not come up with a structured way to think about disease. There were theories about how the plague spread and how to prevent it, but no tests were ever done through observation of large groups of people. The idea of studying groups of people to identify risk factors and disease outcomes had not yet evolved. The lack of a systematic way of testing possible associated between exposures and outcomes was the major factor that prevented advances in understanding the causes of disease and development of effected treatment/prevention.

The black plague still exists today, and kills a few thousand people every year due to anti-biotic resistant strains. However, when identified early it is curable.

Quarantine and Isolation

The concept of quarantine dates back to the early 1400's and the black death. In Italian Qaurintina means 40 days. Travelers and merchandise thought to have been exposed would isolate for a set period of time. This practice persisted until the 19th and 20th century. Isolation is separating someone who has the disease from the rest of the population, which was useful in cases like SARS where the infected is only contagious when symptoms are present. Quarantine is separating someone from the population who might have been exposed, e.g. COVID-19 since one could be contagious without symptoms.