Foundations of wildlife diseases

458 Pages·2014·25.167 MB·English

by  Richard G. Botzler, Richard N. Brown

Foundations WildliFe
of
diseases
Richard G. Botzler and Richard n. Brown
univeRsity oF CaliFoRnia PRess
Foundations of WildliFe diseases

Foundations WildliFe
of
diseases
Richard G. Botzler and Richard n. Brown
univeRsity oF CaliFoRnia PRess
University of California Press, one of the most distinguished
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University of California Press
Oakland, California
© 2014 by The Regents of the University of California
Library of Congress Cataloging-in-Publication Data
Botzler, Richard George, 1942–
Foundations of wildlife diseases / Richard G. Botzler and Richard N. Brown.
pages cm
Includes bibliographical references and index.
ISBN 978-0-520-27609-3 (cloth : alk. paper)—ISBN 978-0-520-95895-1 (e-book)
1. Wildlife diseases. I. Brown, Richard N. (Richard Neal), 1958–
II. Title.
SF996.4.B68 2014
639.9’6—dc23 2013048057
22 21 20 19 18 17 16 15 14 13 10 9 8 7 6 5 4 3 2 1
The paper used in this publication meets the minimum requirements of ANSI/NISO
Z39.48-1992 (R 2002) (Permanence of Paper).8
contents
•
Preface / vii
8 IntroductIon to
non-eukaryotIc agents / 241
•
•
1 IntroductIon / 1
9 eubacterIa / 259
•
•
2 IntroductIon to ImmunIty / 27
10 vIruses / 315
•
•
3 nematodes, acanthocephala,
11 specIal topIcs / 353
pentastomes, and leeches / 45
•
•
12 summary and Future dIrectIons / 377
4 Flatworms: trematodes
and cestodes / 85
Appendix One / 381
•
5 the parasItIc Insects, mItes, Appendix Two / 401
and tIcks / 125 Glossary / 411
• Index / 429
6 kIngdom protIsta / 167
•
7 kIngdom FungI / 205

preface
The discipline of wildlife diseases is a dynamic wildlife diseases, we present a foundation for
field of increasing importance to a conservation- thinking about infective agents and their inter-
conscious society. Beginning as a secondary actions with wildlife.
interest among a group of wildlife managers This book is intended as a first formal intro-
in the early 1900s, it became a formal field of duction to the field of wildlife diseases written
study with the formation of the Wildlife Dis- for upper-division and graduate students who
ease Association (WDA) in 1951; at that time the have a good foundational grounding in biology
WDA primarily comprised wildlife profession- and zoology; these include students studying
als trained in traditional wildlife management, wildlife and natural resources, as well as the
as well as some veterinarians, but all sharing natural and biological sciences, and veterinary
an interest in better understanding the role of students who are extending their interests to dis-
diseases in wildlife populations. eases of wildlife. We do not expect that students
In the intervening years, our increased necessarily have extensive foundations in micro-
understanding of wildlife diseases has led biology, parasitology, or other disease issues.
to clarifying significant conservation issues; With the ideas of this text, we hope students
we recognize that the relationships among will come to understand the basic life history
vertebrate wildlife, infectious agents, ecologi- strategies used by infective agents for being
cal disturbances and loss, pollutants, climate successful among vertebrate wildlife, as well as
change, invasive species, and other factors are understanding the mechanisms by which wild-
very complex. Making sense of the multitude life can defend themselves from these agents.
of specific relationships can be overwhelming. Hosts and infective agents each constantly
Most of these problems cannot be successfully evolve new tools and strategies to gain an advan-
addressed by any one professional, and require tage over the other. We envision host–infective
networking of specialists in diverse fields to agent relations as a dynamic “evolutionary
obtain better understandings. Trained conser- dance” in which each vertebrate host and each
vation professionals, as well as veterinarians infective agent has an array of tools and strat-
with a wildlife background, are essential for egies for gaining an advantage over the other,
successfully addressing these issues. For under- and for countering the tools and strategies of
graduate and graduate students interested in the other. Current wildlife disease relationships
vii
are the result of a perpetual natural selection those members within each group causing dis-
for successful tools and strategies among both eases among wildlife. We then present one or
wildlife hosts and the infective agents. Under- two examples of wildlife pathogens as illustra-
standing these relationships is key to more tions of the main life history strategies in the
fully understanding the ecology and evolution group. For the wildlife pathogens presented, we
of wildlife diseases and to laying the foundation provide a consistent organizational approach
to better understand the important contempo- to allow readers to more easily compare key
rary and leading-edge work being conducted in features among infective agents.
the field. The text is not intended as a descriptive
We use a natural history approach to provide survey of the most common or even the most
a general introduction to wildlife diseases, pull- serious wildlife diseases, a strategy often
ing together information that is distributed over used in parasitology or medical microbiology
a wide variety of texts and professional publica- texts. It will not compete with the specialized
tions into one concise source for the reader. We infectious and parasitic disease texts that play
first give an overview and some basic definitions an important role in summarizing the major
needed for understanding wildlife diseases. diseases affecting vertebrate animals. But by
Because of its importance and applicability for providing a clear foundation for understand-
all discussions of the infective agents, we next ing how wildlife and infective agents interact,
outline basic methods of defense employed by our text provides an important foundation
vertebrate hosts. This is followed by outlining for readers to use these more specialized
the major life history strategies found among texts as they continue developing as wildlife
infective agents. We also cover some important disease professionals.
noninfectious diseases of wildlife, and a few We acknowledge, but do not develop, such
special problems and emerging diseases. contemporary and important wildlife disease
Our primary focus among wildlife is on topics as invasion biology and impacts on faunal
mammals and birds, with limited coverage of structure, co-evolutionary relations, the roles of
amphibians and reptiles. Arthropods and other climate change and ecological disturbances as
invertebrates are addressed as contributors contributors to the emergence of new diseases,
to important disease processes among these or ecosystem approaches to understanding
wildlife hosts. We believe that our emphasis the complex interactions of pathogens and the
on broad ecological comparisons among patho- resulting patterns of disease. Rather, the text
gens using virulence as a transmission strat- is intended to provide the foundation needed
egy, those using chronic carriers as a strategy, by students to thoughtfully and intelligently
and those relying on indirect transmission is address these and other critical topics. Where
unique to our text. possible, we also identify early sources of sig-
For taxonomic purposes, we generally fol- nificant ideas in our discipline’s history; giving
low traditional lines of parasite classification, credit for the ideas allows us to appreciate the
but we also include recent changes reflect- early innovative researchers, and better under-
ing new evolutionary perspectives. We do not stand the evolution of thinking on these topics.
attempt comprehensive coverage of each taxo- We hope you as readers enjoy learning and
nomic group, but emphasize an understanding reflecting on this fascinating, dynamic field
of the variation in life history strategies among of study!
viii preface
ONE
Introduction
CONTENTS
Why Study Wildlife Diseases 1 Density and Disease 10
Human Health 2 Disease Models 11
Domestic Animal Health 3 Causes of Disease 12
Wildlife Health 4
Role of Diseases in Wildlife Populations 13
Select Definitions and Concepts 6
Can Diseases Regulate Wild Populations? 15
Health and Disease 6
Overview and Summary 17
Parasitism 6
Literature Cited 18
Diseases in Populations 9
The study of wildlife diseases encompasses the
Why STudy WIldlIfE dISEaSES
health, disease, and fitness of wildlife, and
the broad range of factors that can potentially A focus on the health and well-being of wildlife
affect their well-being. These factors include themselves is of relatively recent origin. Histori-
a wide array of infectious organisms such as cally, much of the initial interest in the health and
helminths, arthropods, and microorganisms, diseases of wildlife stemmed from other con-
as well as toxins, traumas, metabolic dysfunc- cerns, particularly human health and the health
tions, genetic problems, and habitat fragmen- of domestic animals (Friend 1976, Gulland 1995,
tation. Such factors not only act individually, Simpson 2002). In time, more direct interest
but also may interact synergistically in complex emerged in the wildlife themselves, with an effort
ways to affect wildlife health. In this first chap- to gain a more complete biological and ecological
ter we give a brief summary of the basis for the understanding of how diseases interact with host
emergence of wildlife diseases as a discipline populations; this is exemplified by the emergence
and provide some key general concepts used of wildlife health and conservation medicine as
throughout this text. distinctive disciplines.
1