"Tell me, doctor, is epidemiology dangerous!" Michel C. Thuriaux

confess that I was disconcerted Epidemiology is not limited only to by this question. In trying to reply Hippocrates said ... infectious diseases, not by a long way. I had first of all to think about "Whoever would study medi­ Our food and the manner in which we what epidemiology is, how it is cine aright ... must consider the eat affect our health. James Lind in the used and why. In one of the effect of each of the seasons of 18th century and Kanehiro Takaki in Ioldest texts on epidemiology, Hippo­ the year and the differences the 19th showed the role played by crates of Cos stresses the importance - between them .. . The effect of food in the fight against scurvy and in order to fight the diseases which water on the health must not be beri-beri. At the beginning of this attack communities - of studying the forgotten . .. When a physician century, Joseph Goldberger studied place (where?), the time (when?) and comes to a district previously the deficiencies which affected poor the characteristics of those communi­ unknown to him, he should people in the United States and which ties (who? how?). consider both its situation and provoked insanity in sufficient numbers The epidemiology of the environ­ its aspect to the winds ... Then. to fill the asylums; as a result he ment and of lifestyles were thus think of the soil. whether it be developed methods which are still already subjects of concern about 25 bare and waterless or thickly being applied in the epidemiology of centuries ago. Even older texts found covered with soil and well ­ disorders related to nutrition. in the Indus Valley discussed similar watered . . . Lastl y consider the In the same way, our general life­ preoccupations as regards water life of the inhabitants them­ styles and our working conditions supplies and improvements in sani­ selves: are they heavy drinkers affect health. Last century, in the tation. The development of health and eaters and consequently Mulhouse region of France, Louis­ statistics in the 17th century made it unable to stand fatigue. or - Rene Villerme had already described possible to give better and more being fond of work and exercise the effects of their working conditions systematic answers to the question: - eat wisely but drink sparingly? on the health of the cotton workers. how many? which had been more or . . . A physician who under­ Closer to our own time, in the 1950s, less evaded until then. Various other stands these subjects well . .. the epidemiological studies of Richard factors have since contributed to the would know what epidemics to Doll and Austin Bradford Hill drew development of epidemiology over the expect. both in the su mmer and attention to the active role of tobacco last 200 years. in the winter. and what particu­ in lung cancer. These studies provided The evolution of medicine and lar disadvantages threatened an the basis for the works which have public health in the course of the last individual who changed his made us better able to identify the risks century led to a better knowledge of mode of life ... He wou ld be involved in tobacco and to develop infectious diseases and ways of fighting very successful in the practice of programmes to combat smoking. them. (The application of this know­ medicine." ledge is always topical, and resulted in the eradication of smallpox ten years ago, while these methods continue to be applied today, for example, in the fight against AIDS). But even before the existence had been proved, during the second half of the 19th century, of infectious germs and the laws governing their transmission, "the study of water and habits" had already made it possible to take action on the factors that influence health. In 1849 John Snow, after studying the water supply sources in a London district hard hit by cholera, removed the handle of a pump that supplied water which he considered dangerous. Two years earlier, Ignaz Semmelweis caused a sharp drop in the number of women dying in childbirth in Vienna's hospital by calling for midwives and doctors to wash their hands before examining mothers-to-be.

4 WORLD HEALTH, June 1989 major health care programmes in the policies that would be needed to attain "Our food and the manner in which we eat affect our health., A meal for poor United States. them. They are now striving on a So we can say that epidemiology regular basis to collect the vital children in India. helps us to identify the factors which information which will enable them to Photo T. P. Singh influence our health (by giving answers measure their progress towards the Facing page: /gnaz Semmelweis (181~ to the questions where, when, who, goals. On the basis of this information, 1865) and his hygienic basin how much?). The most important they will then t!y to develop their own encountered the hostility of colleagues question still remains: and then? In new programmes and policies or to who saw no reason for doctors to wash order to reply effectively, it is necessary: improve existing ones. All these will their hands before examining women - "Firstly, to know how to draw con- entail considerable changes and in labour. clusions that result from these readjustments, which are unlikely to be Photos WHO replies (that is the role of the effected without a great deal of heart­ analyses carried out by epidemi­ searching. Finally, epidemiological methods ology); Let me come back to the question have been applied to the development - "And secondly, to want to apply which began this article. All political and use of the health services, whether those conclusions in support of action is risky, and no change can by comparing methods of intervention programmes and policies - or to come about without risk. In the case of (efficacity of the cervical smear in the develop new ones - that will make Semmelweis mentioned above, the risk struggle against cancer of the neck of better health possible (the role of proved to be only too real. Exposed to the uterus) or ways of promoting political decision). the hostility of colleagues who could health, or of establishing what types of It is therefore essential that epidem­ not forgive him for insisting on their service and staff can most efficiently iological knowledge and political will washing their hands before examining take charge of health care activities. support each other. The member women in labour, he died insane and Studies of this type have, for example, countries of WHO recently established in misery in 1865. Without necessarily made it possible to confirm the precise health goals and drew up wishing to go quite so far, it might be effectiveness and usefulness of various useful to recall that, to the degree that categories of personnel in family it supports health policy or even just planning programmes in several coun­ All photos in th is issue which are not marked politics generally, epidemiology is tries. One such study provided the WHO or © for copyright are entries in wHo's neither totally harmless, innocent, nor under-pinning for the setting up and 40th anniversary International Photo without risk. And perhaps that is not evaluating of nurse practitioners in Competition. such a bad thing. •

WORLD HEALTH , June 1989 5