Advances in PARASITOLOGY VOLUME 32 Editorial Board W. H. R. Lumsden Department of Genitourinary Medicine, Royal Infirmary, P. Wenk Tropenmedizinisches Institut, Universitat Tubingen, D7400 Tubingen I , C. Bryant Department of Zoology, Australian National University, G.P.O. Box 4, Lord Soulsby Department of Clinical Veterinary Medicine, University of K. S. Warren Comprehensive Medical Systems, Inc., 461 Fifth Avenue, New York, J. P. Kreier Department of Microbiology, College of Biological Sciences, Ohio State M. Yokogawa Department of Parasitology, School of Medicine, Chiba University, C. Combs Laboratoire de Biologie Animale, Universite de Perpignan, Avenue de Edinburgh EH3 9YW, UK Wilhelmstrasse 3 I, Federal Republic of Germany Canberra, A.C.T. 2600, Australia Cambridge, Madingley Road, Cambridge CB3 OES, UK N.Y. 10017, USA University, 484 West 12th Avenue, Columbus, Ohio 43210-1292, USA Chiba, Japan Villeneuve, 66025 Perpignan CCdex, France Advances in PARASITOLOGY Edited by J. R. BAKER Cambridge, England and R. MULLER International Institute of Parasitology SI Albans. England VOLUME 32 ACADEMIC PRESS Harcourt Brace & Company, Publishers London San Diego New York Boston Sydney Tokyo Toronto ACADEMIC PRESS LIMITED 24/28 Oval Road LONDON NW 1 7DX United Stares Edition published by ACADEMIC PRESS INC. San Diego CA 92101 Copyright 0 1993, by ACADEMIC PRESS LIMITED 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 A CIP record for this book is available from the British Library ISBN 0-12-031732-X This book is printed on acid-free paper Filmset by Bath Typesetting Ltd., London Road, Bath Printed in Great Britain by T. J. Press (Padstow) Ltd, Padstow, Cornwall. CONTRIBUTORS TO VOLUME 32 S. J. BALL, Department of Life Sciences, University of East London, Romford Road, London, El5 4LZ, UK P. F . L. BOREHAM, Queensland Institute of Medical Research, The Bancroft Centre, 300 Herston Road, Herston, Brisbane, Queensland 4029, Australia A. J. DAVIES, School of Life Sciences, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey, KTI 2EE, UK F. k’. LIEW, Department of Immunology, University of Glasgow, Western Infirmary, Glasgow, GI1 6NT, UK A. H . W. MENDIS, School of Biomedical Sciences, Curtin University of Technology, Bentley, Western Australia, 6001, Australia C. A. O’DONNELL, Department of Immunology, University of Glasgow, Western Infirmary, Glasgow, GI1 6NT, UK A. RAIBAUT, Laboratoire de Parasitologie ComparPe, URA CNRS 698, Universitk Montpellier II, Sciences et Techniques du Languedoc, Place EugPne Bataillon, 34095 Montpellier CPdex 5, France J. A. REYNOLDSON, Institute for Molecular Genetics and Animal Disease and School of Veterinary Studies, Murdoch University, Murdoch, Western Australia, 6150, Australia D. J. STENZEL, Analytical Electron Microscopy Facility, Queensland Univer- sity of Technology, George Street, Brisbane, Queensland 4001, Australia R. C. A. THOMPSON, Institute for Molecular Genetics and Animal Disease and School of Veterinary Studies, Murdoch University, Murdoch, Western Australia, 6150, Australia J. P. TRILLES, Laboratoire d’Ecophysiologie des InvertPbrPs, UniversitP Mont- pellier II, Sciences et Techniques du Languedoc, Place Eugene Bataillon, 34095 Montpellier CPdex 5, France D. ZILBERSTEIN, Department of Biology, Technion-Israel Institute of Tech- nology, Haifa 32000, Israel V This Page Intentionally Left Blank PREFACE Unusually for the series as a whole, this volume of Advances in Parasitology has a predominantly protozoological flavour, which we hope may go some way to redressing the overall helminthological bias. The first contribution deals with what the authors, Drs Boreham and Stenzel, refer to as an enigma: the well known but little understood Blastocystis. Both this organism’s taxonomic position and its possibly pathogenic role remain in doubt, but Boreham and Stenzel conclude that Blastocystis is indeed a protist, but is probably sui generis-although perhaps most closely related to the amoeboflagellates. Since its first recog- nition by Alexieff in 191 1, this organism has been variously regarded as a fungus, yeast, the cyst of a flagellate, or a degenerate vegetable cell. Opinion about its pathogenicity has been, and still is, similarly divided; the authors conclude that it is at present premature to attempt to reach a conclusion. Drs Thompson, Reynoldson and Mendis next present a masterly review of the knowledge concerning Giardia which has accumulated since this parasite was last reviewed in this series in 1979 (Vol. 17). The pathogenicity of Giardia is not in doubt, it now being recognized as “one of the ten major parasites of humans”, and nor is its taxonomic position among the flagel- lates. However, the increasing and intriguing (and sometimes conflicting) evidence that Giardia represents a very early branching of the eukaryotic stem is discussed, and the authors conclude that “some caution may be prudent” in reaching a conclusion about this. The review also deals with the relatively newly discovered intranuclear RNA virus, GLV or Giardiavirus, about which much remains to be discovered, and other aspects of the parasite’s morphology, the vexed question of speciation, the life cycle and transmission (concluding that definitive proof of zoonotic transmission in nature has yet to be obtained), biochemistry (which is discussed in consider- able detail), and control. Following the review of the interaction between Leishmania and its macrophage host cells in the previous volume, this volume contains a full overview of current knowledge of the immunology of leishmaniasis by Professor Liew and Dr O’Donnell. Considerable advances in this subject have been made over the last decade or so, including knowledge of the genetic regulation of the response to infection in human and murine hosts, the cellular response (especially the roles of various T cell populations), cytokines and the effector mechanisms by means of which the parasites may be killed as a result of the host’s response to infection. This leads to a discussion of vaccination (which has, of course, been practised for centuries vii ... Vlll PREFACE in the form of “leishmanization” for oriental sore). The authors conclude that leishmaniasis is now perhaps one of the infectious diseases best understood from an immunological viewpoint. Dr Zilberstein reviews, in a compact and concentrated form, current knowledge of the means by which trypanosomatids transport nutrients and ions across their membranes, including proton transport and the proton motive force, and transport of glucose, amino acids and calcium. These mechanisms, which have until relatively recently been a neglected topic, are clearly of great importance in maintaining the parasites’ intracellular homeostasis and thus ensuring their survival within their hosts. Equally clearly, it is possible that a fuller understanding of the mechanisms of transport could lead to the development of directed chemotherapeutic agents, aimed at blocking or disrupting these essential processes. Dr Davies and Professor Ball next review the biology of the coccidian parasites of fish. This very comprehensive, fully and beautifully illustrated chapter complements the review of eimeriid coccidia by Professor Ball and others in Volume 28. This interesting group of organisms, which contains, in the authors’ words, a “bewildering array” of parasites, has until recently been much less studied than the equivalent parasites of mammals and birds. However, the currently growing interest in fish farming and increasing awareness of the potential of these coccidia to cause disease, especially under the intensive conditions inseparable from farming, has led to a tendency to redress this imbalance-a process which will be much helped by the present review. All aspects of the parasites’ biology are covered: life cycles, trans- mission, structure and host-parasite interactions. The authors conclude by summarizing fields in which our knowledge of these parasites has increased considerably and, perhaps more importantly, those in which it has not much increased. This latter category includes the possibility of autoinfection, immunity and pathogenicity, and taxonomy. There is still confusion and argument over the number of valid genera; alongside the well established genera Eimeria and Goussia, should the newer genera Epieimeria, Epigoussia and Nucleogoussia be accepted? The mechanism of oocyst wall formation also remains incompletely understood. The authors conclude optimistically that the significant recent advances in knowledge should provide the basis for controlled experiments to provide answers to these questions. Finally Drs Raibaut and Trilles review the sexuality of parasitic crusta- ceans. This diverse and sometimes bizarre group of parasitic organisms is not well known to the majority of parasitologists but can supply fascinating insights into the evolutionary aspects of comparative parasitology. Parasit- ism has led to a multiplicity of sexual modes with separate sexes and various degrees of hermaphroditism often reflecting the motile or sessile habits of their free-living ancestors. The problems of mate encounter which occur PREFACE ix when one of the partners is fixed, and particularly when both are, have been solved in various ways, and these are discussed and amply illustrated. J. R. BAKER R. MULLER