Advances in PARASITOLOGY VOLUME 22 Editorial Board W. H. R. Lumsden University of Dundee Animal Services Unit, Ninewells Hospital and Medical School, P.O. Box 120, Dundee DDl 9SY,UK A. Capron Director, Institut Pasteur, Centre d'Immunologie et de Biologie Parasitaire, 15 Rue Camille Gukrin, 59019 Lille, Cedex, France P. We& 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, Cambridge, U K and R. MULLER Commonwealth Institute of Parasitology, St. Albans, U K VOLUME 22 1983 ACADEMIC PRESS,, INC. ( t L i r ( trurt 6r.u t* I o v m o w h. Publishrrsl London Orlando San Diego New York Toronto Montreal Sydney Tokyo ACADEMIC PRESS INC. (LONDON) LTD. 24/28 Oval Road, London NW1 7DX United States Edition published by ACADEMIC PRESS, INC. Orlando, Florida 32887 Copyright 0 1983 by ACADEMIC PRESS INC. (LONDON) LTD. AN 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 ISBN 0- 12-03 1722-2 ISSN 0065-308X PRINTED INTHEUNITEDSTATESOFAMERICA 85 86 87 88 9 8 7 6 5 4 3 2 CONTRIBUTORS TO VOLUME 22 JENEFERM. BLACKWELL, Ross Institute of Tropical Hygiene, London School of Hygiene and Tropical Medicine, Keppel Street, London WClE 7HT, England D. S. ELLIS,Department of Medical Protozoology, London School of Hygiene and Tropical Medicine, Keppel Street, London WClE 7HT, England D. A. EVANS,Department of Medical Protozoology, London School of Hygiene and Tropical Medicine, Keppel Street, London WCIE 7HT, England G. J. FRAYHA, Department of Microbiology, School of Medicine, American University of Beirut, Beirut, Lebanon M. A. GEMMELL, Hydatid Research Unit, Research Division, Ministry of Agriculture and Fisheries, University of Otago Medical School, Dunedin, New Zealand J. RUTH LAWSON, Hydatid Research Unit, Research Division, Ministry of Agriculture and Fisheries, University of Otago Medical School, Dunedin, New Zealand R. E. SINDEN,Department of Pure and Applied Biology, Imperial College of Science and Technology,London S W7 2BB, England J. D. SMYTH,Department of Pure and Applied Biology, Imperial College of Science and Technology, South Kensington, London S W7 2BB, England -EN J. I. THORNE,Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP,England D. WALLIKER, Institute of Animal Genetics, West Mains Road, Edinburgh EH9 3JN, Scotland This Page Intentionally Left Blank PREFACE This volume of Advances in Parasitology continues the policy established by Ben Dawes and developed by Professor Lumsden, of attempting to review any aspect of parasitology in which significant developments are being, or have recently been, made. We feel that the traditional division of parasitology into protozoology and helminthology is becoming increasingly artificial. As more emphasis is laid on the subject’s ecological aspects-including interrelationships between parasites and their hosts-and on the cell