Advances In Parasitology [Vol 48] - J. Baker, et al., (AP, 2001) WW

407 Pages·2001·26.61 MB·English

Editorial Board

C. Bryant Division of Biochemistry and Molecular Biology, The Australian
National University, Canberra, ACT 0200, Australia

M. Colluzi Director, Istituto di Parassitologia, Universita Degli Studi di Roma
‘La Sapienza’, P. le A. Moro $00185 Roma, Italy

C. Combes Laboratoire de Biologie Animale, Universite de Perpignan, Centre
de Biologie et d’Ecologie Tropicale et Mediterraneenne, Avenue de
Villeneuve, 66860 Perpignan Cedex, France

W.H.R. Lumsden 16A Merchiston Crescent, Edinburgh, EHlO 5AX, UK

J.J. Shaw Instituto de Ciencias Biomedicas, Universidade de Sao Paula, av.
Prof. Lineu Prestes, 1374,05508-900, Cidade Universitaria, Sao Paulo, SP.
Brazil

Lord Soulsby of Swaffham Prior Department of Clinical Veterinary
Medicine, University of Cambridge, Madingley Road, Cambridge, CB3
OES, UK

K. Tanabe Laboratory of Biology, Osaka Institute of Technology, 5- 16- 1
Ohmiya, Asahi-Ku, Osaka 535, Japan

P. Went Falkenweg 69, D-72076 Tubingen, Germany

Advances
in

PARASITOLOGY

Edited by

J.R. BAKER

Royal Society of Tropical Medicine and Hygiene,
London, England

R. MULLER

International Institute of Parasitology,
St Albans, England

and

D. ROLLINSON

The Natural History Museum,
London, England

VOLUME 48

0 AP

ACADEMIC
PRESS

A Harcourt Science and Technology Company

San Diego San Francisco New York
Boston London Sydney Tokyo

CONTRIBUTORS TO VOLUME 48

B.W. CRIBB, Centre for Microscopy and Microanalysis, Department of
Zoology and Entomology, The University of Queensland, Brisbane,
Queensland 4072, Australia

D.W.T. CROMPTON, WHO Collaborating Centre for Soil-transmitted
Helminthiases, Institute of Biomedical and Life Sciences, University of
Glasgon; Glasgow, G12 8QQ, UK

A.M. DUNN, School of Biology, University of Leeds, Leeds, LS2 9JT,
UK

W. GIBSON, School of Biological Sciences, University of BristoL Bristol
BS8 1 UG, UK

C.ER. HATZ, Department of Medicine and Diagnostics, Tropical
Institute, P.O. Box 4002, Basel, Switzerland

H.A. NOYES, School of Biological Sciences, University of LiverpooL
Liverpool L69 7ZD, UK

C.J. SCHOFIELD, Department of Infectious and Tropical Diseases, London
School of Hygiene and Tropical Medicine, London, WCIE 7HT, UK

J.E. SMITH, Department of Biological Science, University of Salford,
Salford, M5 4WT, UK

J.R. STEVENS, School of Biological Sciences, University of Exeter, Exeter,
EX4 4PS, UK

R.S. TERRY, Department of Biological Science, University of Salford,
Salford, M5 4WT, UK

I.D. WHITTINGTON, Department of Microbiology and Parasitology, The
University of Queensland, Brisbane, Queensland 4072, Australia

PREFACE

The volume starts with a review by Jamie Stevens (University of Exeter, UK)
and colleagues of the evolutionary history of the Trypanosomatidae as revealed
by current molecular studies, including DNA sequencing. The old argument
between proponents of the 'invertebrate first' and 'vertebrate first' theories of
the original hosts of the family seems to have been largely spurious, since it
appears that the transition between monogenetic and digenetic life cycles, in
whichever direction, may have occurred several times during the evolution of
the family. Both monogenetic and digenetic genera seem to be closely related
and, surprisingly, the genus Trypanosoma apparently shares with the line lead-
ing to the monogenetic parasites of invertebrates the distinction of being
among the early or 'lower' trypanosomatids. Recent studies by the authors and
their colleagues have indicated that Trypanosoma is a monophyletic genus,
with T. brucei having evolved only in Africa while T. cruzi arose perhaps in a
southern supercontinent ancestral to South America and Australia since - even
more surprisingly - the subgenus Schizotrypanum appears to be linked to a
little-known species which parasitizes kangaroos. Leishmania and
Trypanosoma also seem to have diverged very early in the group's evolution-
ary history.
Vertical transmission, whereby parasites are passed from generation to gen-
eration of hosts within a host lineage, is a strategy employed by a diverse
range of parasites. In this chapter Alison Dunn, Rebecca Terry and Judith
Smith (University of Leeds, UK) look at transovarial transmission by
microsporidia and draw on their considerable experience with the
microsporidia of arthropods. It is interesting to consider the parallels between
transovarial transmission of parasites with the maternal transmission of cell
organelles such as mitochondria. Vertical transmission has been observed in
many different microsporidian genera but the true importance of this form of
transmission may have been underestimated. In contrast to horizontal trans-
mission, which may be pathogenic due to the release of large numbers of
spores, vertical transmission is rarely associated with host pathology. This
chapter reviews many aspects of transovarial transmission ranging from para-
site adaptations and mechanisms of transmission to the evolutionary origins of
this transmission strategy within the microsporidia. It is intriguing how trans-
ovarially transmitted microsporidia may influence the sex ratios of the host

viii
PREFACE

population and the authors bring together observations and stimulating ideas
concerning the evolution of virulence under transovarial transmission and dis-
cuss the wider impact of this transmission strategy on host ecology and
host/parasite evolution.

Parasites face numerous challenges during their often complex life cycles;

one which is common to many is the need to retain their position in or on their
chosen host. It is well known that each of the three major groups of parasitic
Platyhelminthes possess highly characteristic and specialized organs for
mechanical attachment to their hosts but relatively little attention has been
given to how attachment may be enhanced by chemical means. Ian Whittington
and Bronwen Cribb (University of Queensland, Australia) bring together a vast
body of information concerning 'bioadhesives' secreted by Platyhelminthes.
Whereas bioadhesives in many groups of invertebrates, such as marine
molluscs, have been well studied this is probably the first time that such a
detailed account has been given concerning the Platyhelminthes. The authors
draw our attention to many fascinating questions concerned with a parasite's
ability to adhere to epithelial surfaces such as fish epidermis and the lining of
the vertebrate gut. For example, how is adhesion to a living surface generated
so rapidly? The review considers in detail attachment by adhesives in the
Turbellaria and the Monogenea and provides an insight into gland cell and
possible adhesive secretions in the endoparasitic Cestoda and Digenea. It is
amusing to record that this most comprehensive contribution by Ian and
Bronwen, which suggests many new lines of investigation on tissue adhesion
by parasites, soon became known as 'the glue review' during production.

The fourth review, by Christoph Hatz (Swiss Tropical Institute, Basel,

Switzerland) deals with the use of ultrasonography in the study of the pathology
of schistosomal infections. The technique has proved to be very useful in assess-
ing the extent and development of lesions and monitoring the progress of
individual chemotherapy and of community control. Its non-invasive nature,
safety and the availability of portable apparatus makes it suitable for use in
village clinics and in the field as well as in hospitals, although the need for
trained and experienced staff to produce and interpret the ultrasonograms is a
potential limitation. The use of ultrasound in studying the pathology of the five
species of Schistosoma which infect humans is thoroughly reviewed, together
with summaries of the resulting observations. The chapter concludes with a dis-
cussion of the contribution of ultrasonography to the design and monitoring of
control programmes, much of which is based on the author's own experience.

As more research is carried out on the ubiquitous human roundworm infec-

tion, ascariasis, the more its medical and economic importance is being
recognized. David Crompton (Glasgow University, UK) has reviewed the
wealth of new information which is available on the distribution of Ascaris and
on the morbidity and mortality caused by it. Estimates of its prevalence rise
inexorably and now stand at 1400 million worldwide. The author stresses

PREFACE
ix

particularly the recent findings showing that the most important effects are on
children, whose weight, height and probably cognition in many countries are
clearly deleteriously affected by the presence of infection.

The author has been closely involved in the formulation of control strategies

(he believes that eradication is unfeasible until sanitation in many countries is
improved greatly) and he authoritatively reviews measures which are proving,
or could prove, effective, including their economic implications. He also deals
with many fascinating aspects of the biology of Ascaris such as the relationship
between the human and pig parasites and the possible evolution of the former,
the route of migration in the human body and recent work on the immunology
of infection, including allergic responses of the host.

J.R. Baker
R. Muller

D. Rollinson