Living with Germs: In Sickness and in Health PDF
Preview Living with Germs: In Sickness and in Health
Living with Germs This page intentionally left blank Living with Germs IN SICKNESS AND IN HEALTH John Playfair 1 3 Great Clarendon Street, Oxford ox2 6dp Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Bangkok Buenos Aires Cape Town Chennai Dar es Salaam Delhi Hong Kong Istanbul Karachi Kolkata Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi São Paulo Shanghai Taipei Tokyo Toronto Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford University Press Inc., New York © John Playfair 2004 The moral rights of the author have been asserted Database right Oxford University Press (maker) First published 2004 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organizations. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data Data available ISBN 0–19–280581–9 1 3 5 7 9 10 8 6 4 2 Typeset by RefineCatch Limited, Bungay, Suffolk Printed in Great Britain by Biddles Ltd, www.Biddles.co.uk This book is dedicated to Humphrey Kay, Leonard Cole, Ben Papermaster, and Ivan Roitt, who steered me along my way over 40 years, and to Greg Bancroft, who hauled me into the twenty-first century. The deviation of man from the state in which he was originally placed by nature seems to have proved to him a prolific source of diseases. From the love of splendour, from the indulgence of luxury, and from his fondness for amusement, he has familiarized himself with a great number of animals which may not originally have been intended for his associates. Edward Jenner, 1798 An inquiry into the causes and effects of the variolae vacciniae (cow pox) Foreword by Sir Walter Bodner FRS Most people know that a germ is a very small living organism that causes disease. Germs are microbes, namely that part of the living world that can usually be seen only under a microscope, if at all. The world of the microbe is enormously diverse and includes viruses such as smallpox and HIV, bacteria, fungi and moulds, small worms and little animal-like organisms that cause diseases such as malaria. Most microbes are harmless to us humans, and some are beneficial not only in food such as cheeses or yoghurt, but also by playing an important role in the normal functioning of our gut. Evolution, as Charles Darwin taught us, is driven by natural selection, and among the most adverse challenges that essentially all living organisms face is the attack from germs—those micro- organisms that do cause disease—often referred to as ‘pathogens’. That is not some form of gene, but a name derived from the word ‘pathology’, which is the study of the essential nature of disease; so much of which, especially during most of our evolution, was due to disease-causing microbes. One of the major driving forces of natural selection has thus been to find ways of overcoming germ attacks, since survival in the face of an attack from a pathogen is clearly going to confer a significant selective advantage. A system, called the ‘immune system’, has evolved over many hundreds of millions of years specifically to deal with germ attacks, and its study is ‘immunology’. The importance of immunology is reflected in the number of Nobel prizes given for discoveries in this field, starting from when they were first given at the very beginning of the twentieth century. viii Foreword The earliest, and perhaps most primitive, immune system which we still retain mainly recognizes major classes of chemical differences which are characteristic of pathogens. This is referred to as ‘innate’ immunity. Subsequently, a system evolved to recognize, with exquisite sensitivity, almost any chemical difference between us and the invading pathogens. This is called the ‘adaptive’ immune system. Sometimes the immune system does not function properly, and itself causes disease. Sometimes the immune system can be put to good use, as in making reagents that recognize chemical differences of almost any sort, and these agents are widely used – for example by the pathologist in diagnosing what disease an individual may be suffering from. Immunity may also be put to use in attacking the differences between cancer and normal cells, forming the basis for novel treatments. Immunity may also be the basis for a form of contraception, for example by tricking the immune system into attacking sperm. John Playfair’s book deals with all these different aspects of germs and immunity in a clear and engaging way. Immunology is full of complex ideas, but here they are explained in a manner that anybody, whatever their background knowledge, should be able to understand. Concepts and organisms are clearly defined, and there is an excellent glossary at the end of the book. I could not think of a better way for the non-expert to learn about this fascinating area of science and medicine than to read John Playfair’s book. Even the experts may find a few nuggets here and there, and also discover new ways to explain, in simple terms, the complexities of their field. Walter Bodmer 6th July 2004 Acknowledgements As well as those mentioned in the dedication, I wish to thank my wife, Anthony Lamb, Guy Playfair, Sir Matthew Farrer, Sarah Houston, and Janice Taverne, who helped me to turn the early drafts into (I hope) a reasonably intelligible final product. I am most grateful to Michael Rodgers of Oxford University Press, who was encouraging from the first telephone call. I should add that I am alone responsible for the opinions expressed in this book, and for any factual errors that may have crept into it.
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