Table Of ContentParasites and Western Man
Parasites and Western Man
EDITED BY
R. J. Donaldson
Director of Studies
Centre for Extension Training
in Community Medicine
London School of Hygiene and
Tropical Medicine
~
In~
MTPPREsS
LIMITED
International Medical Publishers
Published by
MTP Press Limited
Falcon House
Lancaster, England
Copyright © 1979 MTP Press Limited
Softcover reprint of the hardcover 15t edition 1979
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, electronic, mechanical, photocopying,
recording or otherwise, without prior
permission from the publishers.
British Library Cataloguing in Publication Data
Parasites and Western Man
1. Medical parasitology
I. Donaldson, Raymond Joseph
616.9'6'0091722 RC1l9
ISBN-13: 978-94-011-6196-1 e-ISBN-13: 978-94-011-6194-7
001: 10.1007/978-94-011-6194-7
Text set in 11/12pt Photon Times
Contents
List of Contributors
VII
Preface
IX
The parasite and the host
G. S.Nelson
2 Insects (Hexapod a) 11
J. W. Maunder
3 Mites and ticks 34
R.E.Church
4 Head lice 57
R. J. Donaldson
5 Nematodes 78
R.Muller
6 Cestodes and trematodes 114
D.R. Seaton
7 Protozoa 133
H.M. Gilles
8 Man and his pets 171
D.E.Jacobs
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VI PARASITES AND WESTERN MAN
9 Man and domestic animals 201
T. E. Gibson
Index 216
List of Contributors
R. E. Church
Consultant Dermatologist
The Rupert Hallam Department of Dermatology
The Hallamshire Hospital
Sheffield
R. J. Donaldson
Director of Studies
Centre for Extension Training in Community Medicine
London School of Hygiene and Tropical Medicine
London
T. E. Gibson
Head
Department of Parasitology
Central Veterinary Laboratory
Ministry of Agriculture, Fisheries and Food
Weybridge
H. M. Gilles
Alfred Jones and Warrington Yorke Professor of Tropical Medicine
Liverpool School of Tropical Medicine
Liverpool University
Liverpool
D. E. Jacobs
Senior Lecturer
Department of Microbiology and Parasitology
The Royal Veterinary College
London
vii
viii PARASITES AND WESTERN MAN
J. W. Maunder
Lecturer
Department of Entomology
London School of Hygiene and Tropical Medicine
London
R. Muller
Senior Lecturer
Department of Medical Helminthology
London School of Hygiene and Tropical Medicine
London
G. S. Nelson
William Julien Courtauld Professor of Medical Helminthology
London School of Hygiene and Tropical Medicine
London
D. R. Seaton
Clinical Lecturer
Department of Tropical Medicine
Liverpool School of Tropical Medicine
Liverpool University
Liverpool
Preface
The purpose of this book is to provide a concise account of those parasites
which affect man in developed countries. Other textbooks relate mainly to the
tropics and subtropics where parasites by comparison are more common. It is
widely believed that this difference in prevalence between tropical and
temperate countries is due to differences in climatic conditions alone. Whilst it
is true that certain vectors can only act as transmitters of disease under
climatic conditions found in the tropics, there are many other instances where
climate per se is not a decisive factor. More often parasitic disease is related to
the poor standards of hygiene, sanitation and nutrition, which characterize
many of these tropical and subtropical areas. The advent of more international
travel has added a new dimension to the study of parasites, with the
appearance of rare and exotic parasitic infections in the West.
This book encompasses the entire field of parasites in developed countries
with a brief reference to other parts of the world whenever appropriate for the
sake of completeness.
Each chapter provides basic information as well as recent advances and
current thinking. Thus the book will serve as an excellent, comprehensive in
troduction to those taking up a specialized interest in the subject, as well as
those who may wish to obtain general information but are not actively working
in the field. Although it is primarily written from a medical and veterinary stand
point, it provides valuable material for other disciplines.
The individual chapters have been contributed by people who practise and
have been involved in research in the fields about which they write. They are all
experienced teachers of students and graduates of different disciplines. Nearly
all the authors have provided extensive reference lists so that a reader can
explore a particular aspect of a topic in greater depth. Emphasis throughout the
book is placed on prevention.
The currently accepted treatment is described for each of the conditions dis
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x PARASITES AND WESTERN MAN
cussed and it is also indicated where treatment is unnecessary. The first chapter
examines in a general way the host-parasite relationship-often an uneasy
relationship possibly because man has been on this planet for so short a period
in the evolutionary time-scale. It is thus important to keep in perspective the
need for intervention to avoid disrupting this fragile balance. There are separate
chapters on insect parasites, nematodes, cestodes and trematodes, and
protozoa. A detailed account of scabies is included in the chapter on mites and
ticks. Infestation by head lice, which appears to be more prevalent in Western
societies, is examined in detail in a separate chapter. The final contributions
from my veterinary colleagues give a balanced viewpoint of the risks to man
from his pets and domestic animals.
I am most grateful to the chapter writers for their help. During the final
stages of the preparation of this text, I gladly acknowledge the generous help
given to me by Jean Coyle, Liam Donaldson, MB, MSc, FRCS (Ed), Nicola
Spencer, BSc and Peter Waters, MA. I was fortunate in having a helpful,
friendly and cooperative publisher who exhibited infinite patience with the
problems that arose from producing this multi-author book.
Dr R J Donaldson, aBE
Director of Studies
Centre for Extension Training in Community Medicine
Department of Community Medicine
London School of Hygiene and Tropical Medicine
1
The Parasite and the Host
G. S. NELSON
INTRODUCTION
The phenomenon of parasitism occurs amongst all groups of infective agents
whether they are viruses, bacteria, fungi, protozoa, helminths or arthropods.
The main concern of this book is with the protozoa, helminths and arthropods,
parasites that are still of public health importance in economically advanced
societies. Our main concern is with the parasites which are naturally
transmitted in advanced countries. It is not generally realized that there are
several parasitic organisms which maintain themselves in these countries with
very high prevalence rates; in fact we are all infected at some time in our lives
with at least one type of parasite and many people even in the most advanced
societies have the ciliated Trichomonas in their genital tracts, the intracellular
parasite Toxoplasma in their reticulo-endothelial system, the pinworm
Enterobius in their bowel, and the wingless insect Demodex under their skin.
Most people are completely unaware that they are infected and even when they
have symptoms the diagnosis is seldom made. Usually they are harmless com
mensals and as we will see later in this chapter they may even be beneficial
symbionts stimulating our immune system so that we reject more pathogenic
organisms.
Most of the parasites that are naturally transmitted in advanced societies are
more prevalent in underdeveloped tropical regions of the world, but the in
crease in world travel for pleasure or for business and the mass movements of
immigrants and emigrants means that some of the parasites that were
becoming rare in the developed world are being reintroduced into areas where
transmission can occur. For example there is a danger of the reintroduction of
malaria, hookworms and filariasis into the warmer regions of Europe and
North America where these infections have almost been eliminated; these
parasites require special vigilance by the public health authorities. Western
man is particularly at risk of developing exotic infections. He has lost his
