Field epidemiology Third Edition

Field Epidemiology


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Field
Epidemiology
Third Edition

Edited by

Michael B. Gregg

1
2008


1
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Copyright © 2008 by Oxford University Press, Inc.
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Oxford is a registered trademark of Oxford University Press
All rights reserved. No part of this publication may be reproduced,
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without the prior permission of Oxford University Press.
Library of Congress Cataloging-in-Publication Data
Field epidemiology / edited by Michael B. Gregg. -- 3rd ed.
p.; cm.
Includes bibliographical references and index.
ISBN 978-0-19-531380-2 (cloth )
1. Epidemiology. 2. Epidemics. I. Gregg, Michael B.
[DNLM: 1. Epidemiologic Methods. 2. Epidemiology--organization & administration. WA 950 F453 2008]
RA651.F495 2008
614.4--dc22
2007040284

987654321
Printed in the United States of America
on acid-free paper


This book is dedicated to the memory of
Alexander D. Langmuir
Originator, teacher, and practitioner of field epidemiology,
whose wisdom, vision, and inspiration have profoundly

strengthened the practice of public health
throughout the world.


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PREFACE

Over the past several decades, epidemiology has become increasingly complex,
theoretical, and specialized. While many epidemiologists are still engaged in the
investigation of infectious disease problems, others are addressing newer challenges such as homicides, unwanted pregnancies, environmental exposures, and
natural disasters. Computers now make it practical to analyze data in seconds that
it might otherwise take weeks or months to calculate. Whole new books have
appeared covering such areas as pharmacoepidemiology, perinatal epidemiology,
and occupational epidemiology.
Because of the increasing specialization in the real world of contemporary
health problems, there is a need for a clearly written, practical, highly usable book
devoted to field epidemiology—the timely use of epidemiology to solve public
health problems. This process involves the application of basic epidemiologic
principles in real time, place and person to solve problems of an urgent or
emergency nature.
This book, intended to meet this ever expanding need, is based both on
science and experience. It deals with real problems, real places, and real people:
nature’s experiment, if you will, rather than carefully designed studies in a laboratory or clinical setting. So, in the lexicon of the epidemiologist, the book will be
addressing issues relating to observational epidemiology—not experimental
epidemiology.
To a great extent, this book is rooted in the experience of the Centers for
Disease Control and Prevention (CDC) over more than 50 years of training health
professionals in the science—and art—of field epidemiology. In 1951, Alexander

D. Langmuir, M.D., CDC’s chief epidemiologist, founded the Epidemic Intelligence
Service (EIS), and its two-year on-the-job training program in practical,
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viii Preface

applied epidemiology. On call around the clock, the trainees, called EIS Officers,
have been available on request to go into the field to help local and state officials
investigate urgent health problems. Before going into the field, however, EIS
Officers receive training at CDC in basic epidemiology, biostatistics, and public
health practice. The three-week, 8-hour-a-day course is designed to equip them
with the essentials of how to mount a field investigation; how to investigate an
epidemic; how to start a surveillance system; and how to apply science, technology, and common sense to meet real-life problems at the grass-roots level of
experience.
Based on the collective experience of the EIS Officers and their mentors, this
book therefore attempts to describe for the field investigator the relevant and
appropriate operations necessary to solve urgent health problems at local, state,
provincial, federal, and international levels.
Part I contains a definition of field epidemiology; a brief review of epidemiologic principles and methods, under the assumption that the reader has some
knowledge of basic epidemiologic methods; and the practice of surveillance. Part
II covers the components of field epidemiology: (1) operational aspects of field
investigations; (2) conducting a field investigation—a step-by-step description of
what to do in the field; (3) survey and sampling methods; (4) using the computer
in field investigations; (5) designing studies in the field; (6) describing epidemiologic data; (7) analyzing and interpreting data; (8) developing interventions; and
(9) communicating epidemiologic findings. Part III describes special issues such
as (1) dealing with the media; (2) legal considerations; (3) immunization practices
and the field epidemiologist; (4) investigations in health care facilities and in
Out-of Home care settings; (5) investigations of environmental, occupational, and
injury problems; (6) field investigations from the local and state perspective;

(7) investigations in international settings, terrorism preparedness, and response
to natural disasters. Finally, there is an extensive description of the necessary
laboratory support for the field epidemiologist and a “walk-through” exercise in
the appendix.
Over the past two decades, it has become clear that the teaching and application of field epidemiology have spread widely throughout the world. This book
has been translated into Chinese, Korean, and Japanese (not yet in print), and
epidemiologists from several other countries have shown similar interest. Such
programs as the Global Health Leadership Officer Programme of the World Health
Organization; the Public Health Schools Without Walls, supported by the
Rockefeller Foundation; and the Field Epidemiology Training Programs (FETP)
started by CDC all attest to the importance and application of field epidemiology
in the practice of public health.
While Field Epidemiology does, indeed, cater the public health epidemiologists practicing in the United States, it is the hope of the editor and the


Preface

ix

contributors to this book that our collective efforts will contribute significantly to
the understanding and practice of field epidemiology worldwide.
M.B.G.
Guilford, Vermont
C.W.T.*
Atlanta, Georgia

*Carl W. Tyler, Jr., former Director of the Epidemiology Program Office, CDC, who wrote the preface
to the first edition of this book.

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I wish to acknowledge the dedicated and helpful assistance of Marianne G.
Lawrence, B.S., and Floyd Grover in the preparation of this book, and the patience
and understanding of my wife, Lila W. Gregg.

xi


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CONTENTS

Contributors, xvii
I.

BACKGROUND

1 Field Epidemiology Defined, 3
Richard A. Goodman and James W. Buehler
2 A Brief Review of the Basic Principles of Epidemiology, 16
Richard C. Dicker
3 Surveillance, 38
Stephen B. Thacker and Guthrie S. Birkhead

II. THE FIELD INVESTIGATION
4 Operational Aspects of Epidemiologic Field Investigations, 67
Richard A. Goodman, James L. Hadler, and Duc J. Vugia

5 Conducting a Field Investigation, 81
Michael B. Gregg

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xiv Contents

6 Surveys and Sampling, 97
Joan M. Herold
7 Using a Computer for Field Investigations, 118
Andrew G. Dean and Consuelo M. Beck-Sagué
8 Designing Studies in the Field, 138
Richard C. Dicker
9 Describing the Findings: Descriptive Epidemiology, 156
Robert E. Fontaine and Richard A. Goodman
10 Analyzing and Interpreting Data, 199
Richard C. Dicker
11 Developing Interventions, 236
Richard A. Goodman, Robert E. Fontaine, James L. Hadler,
and Duc J. Vugia
12 Communicating Epidemiologic Findings, 249
Michael B. Gregg
13 Dealing with the Public and the Media, 262
Bruce B. Dan

III.

SPECIAL CONSIDERATIONS

14 Legal Considerations in Surveillance and Field Epidemiology, 281
Verla S. Neslund, Richard A. Goodman, James L. Hadler,
and James G. Hodge, Jr.
15 Immunization Practices for the Field Epidemiologist, 301
Harry F. Hull
16 Investigations in Health-Care Settings, 315
William R. Jarvis


Contents

17 Investigations in Out-of-Home Child Care Settings, 338
Ralph L. Cordell, Jonathan Kotch, and Michael Vernon
18 Field Investigations of Environmental Epidemics, 355
Ruth A. Etzel
19 Field Investigations of Occupational Disease and Injury, 376
William Halperin and Douglas Trout
20 Field Investigations from the State and Local Health Department
Perspective, 397
Jeffrey P. Davis and Guthrie S. Birkhead
21 Epidemiologic Practices in Low-Income Countries, 419
Stanley O. Foster
22 Terrorism Preparedness and Emergency Response for the Field
Epidemiologist, 439
Daniel M. Sosin and Richard E. Besser
23 Field Investigations of Natural Disasters and Complex Emergencies, 459
Ron Waldman and Eric K.Noji
24 Laboratory Support for the Epidemiologist in the Field, 479
Elaine W. Gunter, Joan S. Knapp, and Janet K.A. Nicholson
Appendix: A Walk-through Exercise, 524

Index, 551

xv


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CONTRIBUTORS

Consuelo M. Beck-Sagué, m.d.

Ralph L. Cordell, ph.d.

Pediatric Infectious Disease
Consultant
Clinton HIV/AIDS Initiative
Dominican Republic

Director, Office of Science Education
Centers for Disease Control and
Prevention
Atlanta, Georgia

Richard E. Besser, m.d.

Bruce B. Dan, m.d.

Director
Coordinating Office for Terrorism Preparedness

and Emergency Response
Centers for Disease Control and Prevention
Atlanta, Georgia

Adjunct Professor
School of Public Health & Health Sciences
University of Massachusetts Amherst
Amherst, Massachusetts
Adjunct Associate Professor
Department of Preventive Medicine
Vanderbilt University School of Medicine
Nashville, Tennessee

Guthrie S. Birkhead, m.d., m.p.h.
Deputy Director
Office of Public Health
New York State Department of Health
Associate Professor of Epidemiology
School of Public Health
University at Albany
Albany, New York

James W. Buehler, m.d.
Research Professor
Department of Epidemiology
Rollins School of Public Health
Emory University
Atlanta, Georgia

Jeffrey P. Davis, m.d.

Chief Medical Officer and State Epidemiologist
for Communicable Diseases and
Preparedness
Division of Public Health
Wisconsin Department of Health and Family
Services
Adjunct Professor
Department of Population Health Sciences
Adjunct Professor of Pediatrics
University of Wisconsin School of Medicine
and Public Health
Madison, Wisconsin

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xviii Contributors

Andrew G. Dean, m.d., m.p.h.

James L. Hadler, m.d. m.p.h.

Consultant in Epidemiology and Informatics
Clinton HIV/AIDS Initiative
Dominican Republic

State Epidemiologist and Director
Infectious Diseases Section
Connecticut Department of Public Health
Hartford, Connecticut

Richard C. Dicker, m.d., m.s.
Professor
Department of Public Health and
Preventive Medicine
St. George’s University School of
Medicine
Grenada, West Indies

Ruth A. Etzel, m.d., ph.d.
Medical Director—Research
Southcentral Foundation
Anchorage, Alaska

William Halperin, m.d.,
m.p.h., dr.p.h.
Chair and Professor
Department of Preventive Medicine
and Community Health
New Jersey Medical School
Chair and Professor
Department of Quantitative Medicine
School of Public Health
University of Medicine and Dentistry
of New Jersey
Newark, New Jersey

Robert E. Fontaine, m.d., m.s.
Medical Epidemiologist
Division of Epidemiology and Surveillance

Capacity Development
Coordinating Office for Global Health
Centers for Disease Control and
Prevention
Atlanta, Georgia

Stanley O. Foster, m.d., m.p.h.
Professor of Global Health
Rollins School of Public Health
Emory University
Atlanta, Georgia

Richard A. Goodman, m.d., j.d., m.p.h.
Public Health Law Program
Office of the Chief of Public Health Practice
Centers for Disease Control and Prevention
Atlanta, Georgia

Michael B. Gregg, m.d.
Private Consultant in Epidemiology
Epidemiologic Training and
Disease Surveillance
Guilford, Vermont

Elaine W. Gunter, b.s., m.t. (ascp)
Former Deputy Director
Division of Laboratory Sciences,
NCEH, Centers for Disease Control
and Prevention
Atlanta, Georgia

Joan M. Herold, ph.d.
Professor Emerita
Rollins School of Public Health
Emory University
Atlanta, Georgia

James G. Hodge, jr., j.d., ll.m.
Associate Professor, Johns
Hopkins Bloomberg School of
Public Health
Executive Director, Center for Law
and the Public’s Health
Core Faculty, Johns Hopkins Berman
Institute of Bioethics
Baltimore, Maryland

Harry F. Hull, m.d
President
H.F. Hull and Associates
Consultant in Infectious Disease
Epidemiology
St. Paul, Minnesota

William R. Jarvis, m.d.
President
Jason and Jarvis Associates
Hilton Head Island, South Carolina

Contributors

Joan S. Knapp, ph.d.

Stephen B. Thacker, m.d., m.sc.

Laboratory Reference and
Research Branch
Division of STD Prevention
National Center for HIV/AIDS, Viral Hepatitis,
STD, and TB Prevention
Coordinating Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, Georgia

Director
Office of Workforce and Career
Development
Centers for Disease Control and Prevention
Atlanta, Georgia

Jonathan B. Kotch. m.d., m.p.h.
Professor and Associate Chair
Department of Maternal and Child Health
University of North Carolina
Chapel Hill, North Carolina

Verla S. Neslund, j.d.
Vice President for Programs
CDC Foundation

Atlanta, Georgia

Janet K.A. Nicholson, ph.d.
Senior Advisor for Laboratory Science
Coordinating Center for Infectious Diseases
Centers for Disease Control and Prevention
Atlanta, Georgia

Eric K. Noji, m.d., m.p.h.
James A. Baker III Distinguished Fellow in
Health Policy
Program in Global Health Security
The Center for Health Innovation
Washington, D.C.

Daniel M. Sosin, m.d., m.p.h.
Senior Advisor for Science and Public
Health Practice
Coordinating Office for Terrorism Preparedness
and Emergency Response
Centers for Disease Control and
Prevention
Atlanta, Georgia

Douglas Trout, m.d.,m.h.s.
Associate Director for Science
Division of Surveillance, Hazard
Evaluations and Field Studies
National Institute for Occupational
and Safety and Health

Cincinnati, Ohio

Michael Vernon, dr. p.h.
Director, Communicable Disease Section
Cook County Department of Health
Oak Park, Illinois

Duc J. Vugia, m.d., m.p.h.
Chief
Infectious Disease Branch
California Department of Health Services
Berkeley, California

Ron Waldman, m.d., m.p.h.
Professor of Clinical Population and
Family Health
Mailman School of Public Health
Columbia University
New York, New York

xix


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I
BACKGROUND

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1
FIELD EPIDEMIOLOGY DEFINED
R i c h a r d A . Go o d ma n
Ja me s W. B u e hl e r

Despite the actual practice of “field epidemiology” in the United States and other
countries for well over a century, definitions for field epidemiology have come to
the fore only recently. Although epidemiologists work in field settings in a variety
of contexts, the term field epidemiology as used in this book describes investigations that are initiated in response especially to urgent public health problems.
A primary goal of field epidemiology is to inform, as quickly as possible, the
processes of selecting and implementing interventions to lessen or prevent illness
or death when such problems arise.
The constellation of problems faced by epidemiologists who investigate
urgent public health problems gives shape to the definition of field epidemiology.
For example, consider the following scenario: At 8:30 a.m. on Monday, August 2,
1976, Dr. Robert B. Craven, an Epidemic Intelligence Service Officer assigned to
CDC’s Viral Diseases Division, received a telephone call from a nurse at a veterans’ hospital in Philadelphia, Pennsylvania. The nurse called to report two cases
of severe respiratory illness (including one death) in persons who had attended the
recent American Legion Convention in Philadelphia. Subsequent conversations
with local and state public health officials revealed that 18 people who had
attended the convention from July 21to July 24 had died during the period from
July 26 to August 2, primarily from pneumonia. By the evening of August 2, an
additional 71 cases had been identified among legionnaires. As a consequence of
3


4

Background

this information, a massive epidemiologic investigation was immediately initiated
that involved public health agencies at the local, state, and federal levels. This
problem became known as the outbreak of Legionnaires’ disease, and the investigation of the problem led directly to the discovery of the gram-negative pathogen
Legionella pneumophila1, 2, enabling further studies of the nature and modes of
transmission of this organism and the epidemiology and natural history of
Legionella infections, as well as more-informed recommendations for prevention.
The Legionnaires’ disease outbreak and the public health response it triggered illustrate the raison d’être for field epidemiology. Using this epidemic as an
example, we can define field epidemiology as the application of epidemiology
under the following set of general conditions:
• The timing of the problem is unexpected.
• A timely response is demanded.
• Public health epidemiologists must travel to and work in the field to solve
the problem.
• The extent of the investigation is likely to be limited because of the imperative for timely intervention and by other situational constraints on study
designs or methods.
While field investigations of acute problems share many characteristics with
prospectively planned epidemiologic studies, they may differ in at least three
important aspects. First, because field investigations often start without clear
hypotheses, they may require the use of descriptive studies to generate hypotheses
before analytic studies can be designed and conducted to test these hypotheses.
Second, as noted previously, when acute problems occur, there is an immediate
need to protect the community’s health and address its concerns. These responsibilities drive the epidemiologic field investigation beyond the confines of data
collection and analysis and into the realm of public health policy and action.
Finally, field epidemiology requires one primarily to consider when the data are
sufficient to take action, rather than to ask what additional questions might be
answered by the data.
Although the timing of acute public health problems that prompt field investigations is typically unexpected, emergencies often unmask latent threats to

health that have gone unrecognized or have been “waiting to happen.” For example, sporadic or epidemic illness may be inevitable if restaurants fail to adhere to
food-management guidelines, if hospitals fail to properly sterilize or disinfect
instruments, if employers fail to maintain workplace safety standards, or if
members of social networks engage in unsafe sexual behaviors. As a result,
field investigations may prompt both immediate interventions and longer-term
recommendations, or they may identify problems that require further study.