History of Public Health

Introduction

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

In the mid-1800's there was a hygine movement, perticularly in the UK, with focus of improvements of cleanless 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. Discribe 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, nomatic groups accumulating waste and contaimination wasn't a problem. Early concpets of disease revolved around superstition, myths and religion (bad spirits, pandora's box, etc).

The agricultural revolution provided more sucure 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 attriacted rodents and insect vectos and with people living in larger groups there was a greater opporunity for transmission of diseases.

The first concept of diseae not founded on superstition was the hippocratic corpus; A Greek concept that disease is caused by an inbalance of the environmnet 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 perscribe changes in diet and lifestyle. It also became the rational for bloodletting, which continued for many centuries dispite 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 dellirium 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 travelled along trade routes to the black sea.

The most popular explaination 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 primative understanding of medicine, however this wasn't due to a lack of technology but the fact that humans had not come up with a structred 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 quarentine dates back to the early 1400's and the black death. In italian Qaurintina means 40 days. Travelers and merchindise thought to have been exposed would isolate for a set period of time. This practice persisted until th 19th and 20th century. Isolation is seperating someone who has the disease from the rest of the population, which was useful in cases like SARS where the infected is only contaigous when symptoms are present. Quarantine is seperating someone from the population who might have been exposed, e.g. COVID-19 since one could be contaigous without symptoms.