According to the World Health Organization (WHO), “health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” As a field, public health can be defined as the evidence-based public and private efforts that preserve and promote health and prevent disease, disability, and death. Major components of public health include population health, community health, mental health, environmental and ecological health, and occupational and recreational health. Although only a minority of veterinarians report primary public health employment, virtually all veterinarians contribute to the overall public health effort.
Epidemiology is “the study of disease in populations and of factors that determine its occurrence over time.” The purpose is to describe and identify opportunities for intervention. Epidemiology is concerned with the distribution and determinants of health and disease, morbidity, injury, disability, and death in populations. For veterinary epidemiology, this intervention is to enhance not only health but also productivity. Distribution implies that diseases and other health outcomes do not occur randomly in populations; determinants are any factors that cause a change in a health condition or other defined characteristic; morbidity is illness due to a specific disease or health condition; mortality is death due to a specific disease or health condition; and the population at risk can be humans, animals, or plants.
Zoonotic diseases are due to pathogens that are maintained in animals but can be transmitted to humans, causing sporadic illnesses and outbreaks. In rare instances, an agent may even become adapted to circulate in human populations, as demonstrated by the 2009 H1N1 influenza pandemic in humans, due to a virus from swine. Veterinarians should be aware of common zoonotic diseases to advise their clients as well as protect their staff.