CHAPTER 12

• What is the definition of symbiosis?


  Association between two or more species
• What is mutualism?

  Both members benefit from the relationship
• How does parasitism differ from mutualism?

  Parasite benefits while host is harmed
• What characterizes commensalism?

  One benefits, the other is neither harmed nor helped
• What does contamination refer to?


  Microorganisms are present
• What is infection?


  Multiplication of parasitic organisms in a host
• What is the origin of the word infection?

  Derived from Latin "inficere"
• What does infestation refer to?

  Presence of larger parasites on the body
• How is disease defined?

  Disturbance in the state of health
• What factors influence pathogenicity?

  Invasion, multiplication, and avoiding host defenses
• What is pathogenicity?


  Capacity to produce disease
• What is virulence?


  Intensity of disease produced by pathogens
• How can virulence be increased?

  Through animal passage
• What is attenuation?

  Reduction of virulence through subculturing
• What is transposal of virulence?


  Passing a pathogen through new host species
• What is normal microflora?


  Organisms that live on or in the body
• What are resident microflora?


  Microbes always present on or in the body
• What are transient microflora?


  Microorganisms present under certain conditions
• What are opportunists?


  Organisms that cause disease under certain conditions
• What is microbial antagonism?


  Normal microflora interfere with pathogen growth
• What are infectious diseases caused by?

  Bacteria, viruses, fungi, protozoa, and helminths
• What is superinfection?


  Fresh invasion or reinfection by a pathogen
• How can treating respiratory disease with antibiotics lead to enteric diseases?

  Due to growth of resistant organisms
• What is mixed infection?


  Presence of more than one species of organism
• What is a communicable disease?


  Disease that spreads from one host to another
• What are noncommunicable diseases?


  Diseases not spread from one host to another
• How are contagious diseases related to infectious diseases?

  All contagious diseases are infectious
• What are inherited diseases caused by?


  Abnormalities in chromosomes or genetic factors
• What are congenital diseases?


  Defects present at birth due to various causes
• What are degenerative diseases?


  Disorders that develop as aging occurs
• What are nutritional deficiency diseases?


  Diseases that lower resistance to infections
• What are endocrine diseases caused by?


  Excesses or deficiencies of hormones
• What are immunological diseases?


  Diseases due to malfunction of the immune system
• What are neoplastic diseases?


  Diseases involving abnormal cell growth
• What are iatrogenic diseases?


  Diseases caused by medical procedures or treatment
• What are idiopathic diseases?


  Diseases with unknown causes
• What are symptoms?


  Subjective changes not apparent to an observer
• What are signs?


  Objective changes observable by a veterinarian
• What is a syndrome?


  A specific group of symptoms or signs
• What are Koch's postulates?

  Criteria to establish a causative agent of disease