Survey Toolbox for Aquatic Animal Diseases

376 Pages·2002·2.49 MB·English

Survey Toolbox for Aquatic Animal Diseases
To Catriona, as always
Survey Toolbox for Aquatic Animal
Diseases
A Practical Manual and Software Package
Angus Cameron
Canberra 2002
The Australian Centre for International Agricultural Research (ACIAR) was
established in June 1982 by an Act of the Australian Parliament. Its mandate is to
help identify agricultural problems in developing countries and to commission
collaborative research between Australian and developing country researchers in
fields where Australia has a special competence.
Where trade names are used this constitutes neither endorsement of nor
discrimination against any product by the Centre.
© Australian Centre for International Agricultural Research 2002
Cameron, A. 2002. Survey Toolbox for Aquatic Animal Diseases. A Practical
Manual and Software Package. ACIAR Monograph No. 94, 375p.
ISBN 1 86320 350 8 (print version)
ISSN 1447-090X
(electronic version)
ISBN 1 86320 351 6
Survey Toolbox for Aquatic Animal Diseases 5
Contents
1 Introduction and background 9
2 Aquatic animal health 17
3 Principles of passive (general) surveillance 31
4 Principles of active surveillance 47
5 Sampling principles 69
6 Sampling applications 95
7 Principles of data and specimen collection 119
8 Collecting information from people 129
9 Data management 145
10 Survey design and planning 167
11 Prevalence surveys 175
12 Production surveys 193
13 Incidence rate surveys 207
14 Surveys to demonstrate freedom from disease 227
15 Trainers’ guide 241
16 Lesson plans 251
17 Activity sheets 287
Appendixes
A Introduction to epidemiology for aquatic animal scientists 307
B Glossary 363
C Forms 369
D Contents of CD 375
6
About the author
Angus Cameron is a veterinarian with a special interest in epidemiology,
surveillance and information systems in developing countries. He graduated from
the University of Sydney in 1988, and worked in dairy cattle practices in Victoria for
several years. He completed a Masters degree in dairy cattle medicine and surgery
through the University of Melbourne in 1992. Angus became a member of the
Australian College of Veterinary Scientists in 1993.
Angus has lived and worked in Thailand and Laos, where he undertook his
PhD studies in active surveillance and geographical information systems for animal
health. This degree was awarded by the University of Queensland in 1998.
He now works as a veterinary consultant and is a Director of AusVet Animal
Health Services Pty Ltd, providing epidemiological services to Australia and
Southeast Asia. He regularly provides training, program design and other
consultancies in aquatic animal health as well as livestock to countries throughout
the region including Indonesia, Philippines, Vietnam, Thailand, Laos, Myanmar and
India.
When not travelling, Angus lives and works in the Blue Mountains, New South
Wales, Australia.
Acknowledgments
This book grew out of an earlier ACIAR publication, Survey Toolbox for Livestock
Diseases, and I would like to thank all the people who contributed to that work.
Without the ongoing support of ACIAR, and in particular Barney Smith and
Peter Lynch, it would not have been possible to complete this book. They deserve
the thanks of developing country scientists around the world for funding,
publishing and widely distributing books such as this and many others like it.
In writing this book, I have been fortunate to be able to draw from the expertise
of a wide group of experienced aquatic animal health scientists, who have
generously contributed their time and wisdom to make this book as useful and
relevant as possible. Many of them gathered in Bangkok in 2001 to help plan the
content and structure of the book, while others have reviewed drafts of the work:
Melba Reantaso, Jimmy Turnbull, Phan Thi Van, Chris Baldock, Ian MacRae, Celia
Lavilla-Pitogo, Barbara Nowak, Supranee Chinabut, Pornlerd Chanratchakool,
Margaret Crumlish, Dan Feagan, Richard Friend, Huang Jie, Somkiat
Kanchanakhan, Jim Lillie, and Sih Yang Sim.
There are yet others, scientists and farmers too numerous to name, who have
had the kindness and patience to help teach me something about a range of different
aquatic animal production systems.
Survey Toolbox for Aquatic Animal Diseases 7
Guide to the manual
What do you want to do?
Carry out a survey Learn more about surveillance
What type of information
do you want to collect? Learn more about disease
in aquatic animals
Chapter 2
What is a passive disease
surveillance system?
Chapter 3
Estimate disease prevalence
Chapter 11 What is an active disease
surveillance system?
Chapter 4
Estimate production
Chapter 12 Methods for selecting a sample
Chapter 5 & 6
Estimate disease incidence Collecting specimens from
Chapter 13 aquatic animals
Chapter 7
Detect disease or demonstrate
Collecting information from
freedom from disease
farmers and fishers
Chapter 14
Chapter 8
I’m not sure Learn more about
Page 14 epidemiology
Appendix A

1
Introduction and background
Purpose and scope of manual 10
Who is this book for? 11
Notes for translators 11
How to use this book and software 12
9
10 Chapter 1: Introduction and background
Purpose and scope of manual
Aquatic animals have provided an important source of food to humans for many
thousands of years. First through the capture of wild fish, and later through
aquaculture, aquatic animals have played a significant role in the diet of different
people all over the world. Traditional fishing and farming systems continue to be
used in many developing countries, but recently they have been supplemented by a
massive growth in both highly efficient ‘industrialised’ fishing methods, and a
dramatic intensification and commercialisation of aquaculture. The result has been
a very large increase in aquatic animal production, meeting some of the increasing
demands of a growing world population. However, increased production has come
at a cost. Efficient fishing processes run the risk of rapidly overfishing existing
stocks. Intensive farming systems use higher stocking densities and in some cases a
variety of additives, contributing to environmental degradation and an increased
risk of disease. Globalisation and increased trade have made the movement of
aquatic animals around the world, either intentionally or unintentionally (e.g. in
ballast water) simple and rapid. Pathogens move with these aquatic animals, and
find themselves in new ecological niches. In some cases, this can result in disastrous
outbreaks of disease.
In developed countries, with highly intensive production systems, new disease
outbreaks can be extremely damaging to the fishing or aquaculture industries.
However, due to the favourable economic situation, the damage is usually limited,
and doesn’t impact dangerously on the livelihood of a great many people. In
developing countries, on the other hand, relatively more people depend on aquatic
animal production for their food and income. A widespread disease outbreak has the
potential to cause significant hardship to many people. The resources in such
countries are often inadequate to either provide support for the people suffering
from the consequences of a disease outbreak, or adequately support the research and
disease-control activities to address the problem.
The prevention, control, and eradication of aquatic animal diseases depend on
a good understanding of the disease and its distribution. Epidemiologically
structured disease surveys are one of the most important tools to provide
information about factors influencing the occurrence of disease, and its distribution.
Conducting an effective aquatic animal disease survey in a developed country is
often very challenging, even with adequate resources, but the many constraints
faced in developing countries make the task even more difficult. One of those
constraints is access to information about survey techniques suitable for developing
countries, and appropriate for use in aquatic animal disease surveys.
This book aims to provide this information. It deals specifically with the
collection of reliable, high quality information about aquatic animal diseases and
production, using fast, inexpensive techniques that are suitable for developing
countries.
The characteristics that make these techniques suitable for use in developing
countries (inexpensive, rapid, reliable) also make them very attractive in other
countries. It is therefore expected that this book will be of value to those studying
aquatic animal diseases in any part of the world.
In this book, both ‘aquatic animals’ and ‘disease’ are defined broadly. Aquatic
animals are considered to be those animals that spend at least part of their life cycle