Veterinary Clinical Epidemiology

From Patient to Population

Ronald D. Smith

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9780429688232
• Edition: 4
• Topic: Biological Sciences
• Subtopic: Microbiology & Molecular Biology
• Index: Biological Sciences

4* Doody's Review!

Ideal for veterinary students, residents and clinicians, the fourth edition of this bestselling textbook has been fully updated in line with developments in research and teaching. The logical chapter progression reflects the stages in a clinical case work-up and how epidemiological concepts and methods contribute. This new edition

• provides guidelines for improving patient and population health outcomes, and detecting emerging diseases through systematic evaluation of patient encounters and electronic medical records

• 
  
  

• incorporates new methodologies and concepts drawn from the recent veterinary practice literature

• 
  
  

• updates chapter content including expanded coverage of risk, statistical and economic analyses, and surveillance for emerging diseases

• 
  
  

• more than 60 examples of clinical research drawn from the international veterinary practice literature presented as structured abstracts; follow-up questions invite the reader to participate in the analysis of results

• 
  
  

• online links tofull text versions of more than half of structured abstracts and more than 40% of the book's 174 literature citations

• 
  
  

• updates the listing and review of public and private online resources, including guidelines for online literature searching and critical evaluation of clinical reports.

• 
  
  

Today's veterinary curricula places greater emphasis on experiential/problem-based learning versus discipline-oriented instruction. This fourth edition is ideally suited to introduce epidemiologic concepts and methodologies to veterinary students in the context of the patient encounter, and should be of use at any point in the veterinary curriculum.

1

Introduction

1.1 Definitions

Over the years, there have been many definitions of epidemiology. Some examples follow:

A.“…the study of the health status of populations…” (Schwabe et al., 1977)

B.“…Epidemiology is nothing more than ecology with a medical and mathematical flavor.” (Norman D. Levine, 1990, personal communication)

C.“The branch of medicine that deals with the study of the causes, distribution, and control of disease in populations.” (American Heritage Medical Dictionary, 2007)

D.“The study of the determinants of disease events in populations.” (Mosby’s Medical Dictionary, 2009)

E.“Epidemiology is the study of the distribution and determinants of health-related states or events (including disease), and the application of this study to the control of diseases and other health problems.” (World Health Organization, 2019, https://www.who.int/topics/epidemiology/en/)

Common threads in the above definitions are revealed if we consider their origin (Wikipedia contributors, 2019, https://en.wikipedia.org/wiki/Epidemiology). The term epidemiology derives from three Greek words: epi (“about” or “upon”), demos (“populace” or “people of districts”), logos (“word,” thus science or theory). The term epizootiology is sometimes used in reference to comparable studies in animal populations. The distinction is useful when one wishes to describe the state of disease in human or animal populations specifically, particularly when discussing zoonotic disease. For most purposes, however, epidemiology is understood to refer to all animal populations, human and otherwise. Likewise, to avoid confusion, it is preferable to use the term epidemic in lieu of epizootic, and endemic in lieu of enzootic wherever possible. Thus, a simple definition of epidemiology that captures the spirit of earlier definitions and reflects the emphasis of this book is “…the research discipline concerned with the distribution and determinants of disease in populations” (Fletcher et al., 1982).

This definition alone does not appear to provide sufficient grounds for creating a separate discipline. After all, laboratory researchers study disease in populations of animals, populations that may comprise hundreds or thousands of individuals. Furthermore, laboratory researchers address the same sorts of questions as do epidemiologists—questions such as the cause, clinical signs, diagnosis, treatment, outcome, and prevention of disease. An important distinction, however, is that epidemiologists study disease in its natural habitat, away from the controlled environment of the laboratory. Epidemiology deals with naturally or spontaneously occurring, rather than experimentally induced, conditions.

The foregoing definitions imply that epidemiology is concerned with the population rather than the individual. To a certain extent this is true. However, an understanding of health and disease in populations is fundamental to medical decision-making in the individual.

The discipline of epidemiology is a critical component of the One Health initiative. One Health focuses on delivering collaborative, multidisciplinary solutions to complex problems at the animal, human, and environmental interface. This approach brings together the strengths of multiple health science professionals including veterinarians, physicians, public health professionals, epidemiologists, ecologists, economists, social scientists, toxicologists, and others—working locally, nationally, and globally—to attain optimal health for people, domestic animals, wildlife, plants, and our environment. Examples of problems that are the focus of the One Health approach are zoonotic and emerging diseases, food safety, antimicrobial resistance, disaster preparedness, and disease surveillance and control in domestic animals and wildlife. One Health embraces the idea that complex problems at the human-animal-environmental interface can best be solved through multidisciplinary communication, cooperation, and collaboration across disciplines and sectors.

1.2 Epidemiologic Approaches

Epidemiology has its roots in disease surveillance and outbreak investigation. Many consider that epidemiology was “born” during the cholera investigations conducted by John Snow in London in the mid 1800s. However, examples of outbreak investigation can be documented as far back as the Greek and Roman eras (Morens, 2003). Over the years, a number of epidemiologic disciplines and associated methodologies have emerged. These categories are somewhat arbitrary but illustrate some of the ways in which epidemiology contributes to veterinary and human medicine.

1.2.1 Quantitative Epidemiology

Quantitative epidemiology strives to q...