Public health is a kind of science that studies the health of groups of people.
The population in question can be as small as a handful of people or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). Public health has many sub-fields, but is typically divided into the categories of epidemiology (which studies the spread of disease), biostatistics (the study of who is sick and why) and health services. Environmental, social and behavioral health, and occupational health, are also important fields in public health.
In some ways, public health is a modern idea, although it has a very long history. From the early beginnings of human civilization, it was recognized that polluted water and lack of proper waste disposal may spread diseases.
Public Health and Infrastructure[edit | edit source]
Four or five hundred years ago, Europe was a very different place. There was very little scientific knowledge about the world, and people did not understand why they got sick or how to get well. There was no electricity, no gas, very little plumbing or organized sewage disposal. Europe was very poor. As a result, Europeans had many of the same health problems which are found all over the world in poor areas today. Europeans built up their infrastructure over a long period of time, several hundred years.
One very important historical event is the story of John Snow and the Broad Street Pump. This happened in London in about 150 years ago, in 1854. London was in the middle of an outbreak of cholera. At the time, Europeans did not know what caused cholera. People saw that a lot of people were getting sick and dying, and they ran away to other places hoping they would not get sick too. One man, a doctor called John Snow, watched who was getting sick very carefully. He made a map and put a mark on the map for each person who had got sick and died.
This map showed a very important pattern that had not been seen by anybody before John Snow. It showed that the people who were within walking distance of a water pump (or a well) on Broad Street were the ones getting sick. From this fact, and from the fact that people who lived in the area but got their water from another source did not get sick, John Snow discovered two things: cholera was spread from drinking water, and the water from the well on Broad Street carried the disease.
When the authorities took the handle off the pump at the well so nobody could drink from it, the cholera outbreak slowed down a lot. The well turns out to be very close to a sewer pipe which had been leaking germs into the water and making people sick. The well was closed, and the link between infrastructure and disease was now proven.
As a result of John Snow and the Broad Street Pump, people in London and later around the world came to understand that their health and well-being rests on their infrastructure sometimes. People got together and asked for good wells and good sewage systems so that they and their families could stay healthy. It took many years for this work to be completed, but people in Europe, America and other wealthy areas of the world very rarely get sick from bad water or sewage any more, although it does happen sometimes.
Public Health and Infectious Disease[edit | edit source]
Some kinds of public health problems are caused by diseases which are transmitted from one person to another. One example is tuberculosis. Tuberculosis was a very common problem all over the world until a good understanding of the disease helped scientists and doctors invent treatments. Less than 100 years ago, many famous people died from the disease, including artists, writers, philosophers, scientists, politicians and even some kings and queens.
Three things helped make tuberculosis less of a problem. The first is the invention of antibiotics. Antibiotics are powerful medicine which can cure some but not all infectious diseases. They are like poisons which do not harm people, but harm the germs which give people diseases. The first antibiotic invented is called Penicillin. It was discovered in 1928 by Sir Alexander Fleming. Once these medicines were discovered, it became possible to cure people who were sick from tuberculosis although it is still difficult and expensive even today.
The second thing that made tuberculosis less of a problem was the discovery of a vaccine. The tuberculosis vaccine is an injection given to children which hurts rather a lot (you may have heard stories about this) but after you have the injection, you will never ever become sick from tuberculosis. By making sure that almost all children receive this vaccine, many countries have almost no people sick with tuberculosis.
The third thing which helps is finding out who is sick with tuberculosis and making sure that they are treated. The germs which cause this disease can travel from a sick person to a well person through the air. By making sure that people who are sick are treated, the disease can be stopped from spreading. This is the same kind of process that John Snow used to discover that the Broad Street Pump made people sick. It is a kind of science called epidemiology.
These three factors together helped slow down the spread of tuberculosis, and reduced the number of people dying a lot. However, some kinds of tuberculosis are becoming very hard to treat with antibiotics and this is a growing problem all over the world. It is very important that antibiotics are treated with respect and that if you are ever given antibiotics, you finish all the pills you are given. Only taking a few pills until you feel better helps diseases become harder and harder to treat in the long run. If you want to understand exactly how this works, it is called "developing drug resistance" or the study of "drug-resistant bacteria". XTR-TB and HDR-TB are two kinds of tuberculosis which are hard to treat because they developed drug resistance.
Work and Lifestyle Issues in Public Health[edit | edit source]
In London around 100 years ago, people who made matches for lighting fires used to get sick. They got a special form of cancer of the jaw, called Phossy Jaw. At the time no scientists understood exactly why these workers got this disease. But because it only affected people who worked in these factories, the link between those factories and that disease was well understood. This is called an "occupational health" issue - it is a kind of disease that is common among people who do a particular kind of job. In this instance, as the disease was better understood, and people campaigned for changes in working conditions, the disease was eliminated and people who made matches stopped getting jaw cancer.
An example of a "lifestyle issue" in public health is heart disease. The people of Scotland suffer a lot of diseases of the heart and often die from heart attacks. Many factors contribute to this situation but one of the most important causes of heart disease in Scotland is that we often eat foods with a lot of fat, and foods which are fried. Because of this diet, we tend to get diseases of the heart. Scottish people who ate a diet with less fats would be less likely to get sick. The diseases are caused not by being Scottish, but by the habits of life which are common in Scotland.
Conclusions and Things to Think About[edit | edit source]
Public health is a major occupation of many governments, particularly those in richer countries. Public health problems are often taken very seriously, especially where infectious diseases are concerned.
However, as you can see from these examples, even countries that now have very high standards of public health only developed these standards in the last hundred or two hundred years, and the standards continue to change as scientists discover more about the origins and causes of some kinds of disease.
Poorer countries learn from the public health process that richer countries have gone through already. For example, nobody has to re-discover that cholera is carried by contaminated water. That is a fact which can be learned now. Many important things are known about public health. It is an important field of study.