Advances in PARASITOLOGY VOLUME 21 Editorial Board W. H. R. Lumsden University of Dundee Animal Services Unit, Ninewells Hospital and Medical School, P.O. Box 120, Dundee, DD1 9SY, UK A. Capron Director, Institut Pasteur, Centre d'Immunologie et de Biologie Parasitaire, 15 Rue Camille Gutkin, 59019 Lille, Cedex, France P. Wenk Tropenmedizinisches Institut, Universitat Tubingen, D7400 Tubingen 1, Wilhelmstrasse 31, W. Germany C. Bryant Department of Zoology, Australian National University, Box 4, G.P.O.. ,Canberra, A.C.T. 2600, Australia E. J. L. Soulsby Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK K. S. Warren Director for Health Sciences, The Rockefeller Foundation, 1133 Avenue of the Americas, New York, N.Y., 10036, USA J. P. Kreier Department of Microbiology, College of Biological Sciences, Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210. USA M. Yokogawa Department of Parasitology, School of Medicine, Chiba University, Chiba, Japan Advances in PARASITOLOGY Edited by J. R. BAKER Culture Centre of Algae and Protozoa, Cambria'ge and R. MULLER Commonwealth Institute of Parasitology, St. Albans VOLUME 21 1982 ACADEMIC PRESS A Subsidiary of Harcourt Brace Jovanovich, Publishers London New York Paris San Diego San Francisco Slo Paul0 Sydney Tokyo Toronto ACADEMIC PRESS INC. (LONDON) LTD. 24/28Oval Road, London NWl United States Edition published by ACADEMIC PRESS LNC. 111 Fifth Avenue, New York, New York 10003 Copyright 0 1982 by ACADEMIC PRESS INC. (LONDON) LTD. All Rights Reserved No part of this book may be reproduced in any form by photostat, microfilm,or any other means, without written permission from the publishers British Library Cataloguing in Publication Data Advances in parasitology. Vol. 21 1. Veterinary parasitology 591.2’3’05 SF810.H3 ISBN 0-12-031721-4 LCCCN 62-22124 Typeset by Bath Typesetting Ltd., Bath and printed in Great Britain by Thomson Litho Ltd., East Kilbride, Scotland CONTRIBUTORS TO VOLUME 21 Y. W. IAKE, Division of Experimental and Cellular Pathology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 lQP,England W. I. MORRISON, International Laboratory for Research on Animal Diseases, P.O. Box 30709, Nairobt, Kenya MAX MURRAY, International Laboratory for Research on Animal Diseases, P.O. Box 30709, Nairobi, Kenya M. D. RICKARD,University ofhielbourne, Veterinary Clinical Centre, Princes Highway, Werribee, Victoria 3030, Australia M. J. TURNER, MRC Biochemical Parasitology Unit, Molten0 Institute, University of Cambridge, Downing Street, Cambridge CB2 3EE, England D. D. WHITELAW, International Laboratory for Research on Animal Diseases, P.O. Box 30709, Nairobi, Kenya J. F. WILLIAMS, Department of Microbiology and Public Health, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA This Page Intentionally Left Blank PREFACE Astute readers will already have noticed that there are now only two editors of “Advances in Parasitology”. On the retirement of Professor W. H.R. Lumsden from the senior editorship, the editors and the publishers decided to broaden the range of expertise available to advise upon policy and propose or criticize contributions. An international editorial board composed of experts in as many fields of parasitology as possible has been invited to advise the editors generally and to help on specific topics when required. We were delighted when the distinguished scientists whose names are listed on p. ii agreed to serve as board members. Their wide experience and knowledge will help us considerably, and cannot fail to improve the coverage and raise the standard of the material inclu