Veterinary Epidemiology and Zoonosis

INTRODUCTION

• The widely accepted definition of health given by World Health Organization (WHO) is “health is a stage of complete physical, mental and social well-being and not merely an absence of disease”. Health is the solid foundation on which man’s happiness rests and health is man’s most precious possession.  
• Approximately four-fifths of infections of man are shared in nature by other vertebrate animals. These shared infections are called zoonoses.
• In recent years, zoonoses and communicable diseases common to man and animals have gained increasing attention worldwide, that have their origins in infected animals, such as rabies or influenza or tuberculosis, have high attention and need for a better understanding of animal diseases in terms of their epidemiology, mechanism of transmission to man, diagnosis, prevention and control.
• As a result of dynamic of human population, change of life style, ecological encroachment for agricultural activities and subsequent exposure to little known flora and fauna, animal migration and trade, etc. have increased the possibility transmission and pose a threat to human population.
• Zoonoses research strengthened the concept of “one medicine” by the way of microbiological revolution of the late 19^th century and in development of epidemiology as medical ecology.
• A biological pathogen has to be a chronic infection or follow different strategies to survive either in the environment or in the animal and/or human beings or stay alive in the host for long periods or have a non-human reservoir in which to live while waiting for new hosts to pass by. In fact, for many human diseases, the human is actually an accidental victim and a dead-end host. 
• It is very important to know,
  • What is the status of zoonoses worldwide
  • Why does it occur?
  • When does it occur?
  • How does it occur?
  • Where it occurs?
  • Who are the victims?
• These questions initiate to study about the zoonotic diseases with following objectives,
  • Understanding the meaning of zoonoses?
  • How zoonotic diseases are classified and defined?
  • What are the sources of zoonotic diseases and how they spread and are transmitted?
  • Understanding and recognizing the different types of zoonotic diseases
  • To know the interaction between agent, host and environment in the process of spread of zoonotic diseases
  • To recognize, identify and molecular characterize the causal agents
  • To know the epidemiological features and its distribution around the world
  • To know and understand the spectrum of host specificity as primary host, reservoir host, accidental host etc.
  • To understand pathogenicity, morbidity and mortality of the zoonotic disease
  • To analyze the socio-economic implications
  • To reduce the loss of man-hours or man-days
  • To diagnose zoonotic diseases as early as possible in order to recommend correct therapy to minimize the illness and risk of spread of infection
  • To apply prevention, control and eradication of zoonotic diseases
  • To help international organizations like WHO, FAO, etc. on monitoring and surveillance of zoonoses throughout the world
  • To impart health education and awareness about the zoonotic diseases and their public health significance to the public