• Acute: Having a short or relatively severe course
  • Carrier: Apparently health animal that harbors disease organism and is capable of transmitting them to other animals
  • Chronic: Of long duration
  • Contagious: Infectious disease that may be transmitted from one individual to another
  • Diagnosis: Art of distinguishing one disease from another
  • Disease: Any departure form normal state of health
  • Infectious: Capable of causing disease
  • Immunity: Ability to resist infections from normal exposure to disease agents
    • Active immunity: Acquired by recovery from the disease or by vaccination
    • Passive immunity: Achieved by passing of antibodies from the hen to the chick through the egg
  • Lesion: Abnormality of some aspect of an organ or tissue (usually size, shape, color or structure)
  • Morbidity: Incidence of a disease in a flock
  • Mortality: Death rate; % of individuals that die
  • Prevention: Not letting the disease occur
  • Sign: Evidence of a disease
  • Symptom: Subjective evidence of the disease being present
  • Treatment: Promoting recovery or preventing the spread of the disease once it has occurred
  • Vector: Mechanical transmission of a disease