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•  are foreign, infectious microbes that cause sickness and disease

  Pathogens
• scientific study of diseases concerned with:

  Etiology (cause)

  Pathogenesis (development)

  Effects of the disease


  Pathology         
• invasion and growth of pathogens in the body

  Infection
• abnormal state in which part or all the body is incapable of performing normal functions.


  Disease
• an organism that shelters and supports the growth of pathogens.


  Host
• mouth, skin, digestive, urogenital


  Human Microbiome   
• prevents pathogens from causing infection

  Microbial Antagonism
• Pathogens


  Foreign, infectious microbes that cause sickness and disease
• Pathology


  Scientific study of diseases concerned with etiology (cause), pathogenesis (development), and effects of the disease
• Infection


  Invasion and growth of pathogens in the body
• Disease


  Abnormal state in which part or all the body is incapable of performing normal functions
• Host


  An organism that shelters and supports the growth of pathogens
• Human Microbiome


  • Mouth
  • Skin
  • Digestive
  • Urogenital
• Microbial Antagonism


  Prevents pathogens from causing infection
• Types of Symbiosis


  • Commensalism: one organism benefits, other is unaffected
  • Mutualism: both organism's benefit
  • Parasitism: one organism benefits and one is harmed
• Commensalism


  • Staphylococcus epidermidis on the skin
• Mutualism


  • E. coli bacteria in the large intestine
• Parasitism


  • Influenza virus on a host cell
• Koch's Postulate


  1. The suspected causative agent must be absent from all healthy organisms but present in all diseased organisms

  2. The causative agent must be isolated from the diseased organism and grown in pure culture

  3. The cultured agent must cause the same disease when inoculated into a healthy susceptible organism

  4. The same causative agent must be then be reisolated from the inoculated diseased organism
• Sign


  Measurable changes
• Symptom


  Subjective changes in the body
• Syndrome


  Groups of signs and symptoms that always accompanies a specific disease
• Communicable Disease


  Transmitted directly or indirectly from one host to another
• Contagious Disease


  Very communicable disease that is capable of spreading easily and rapidly from one person to another
• Non-communicable Disease


  Caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another
• Classifying Infectious Diseases by Occurrence


  • Sporadic
  • Endemic
  • Epidemic
  • Pandemic
• Classifying Infectious Diseases by Severity/Duration


  • Acute infection
  • Latent Infection
  • Chronic Infection
  • Slow virus
• Acute infection


  • Measles
• Latent Infection


  • Herpes simplex
• Chronic Infection


  • Hepatitis B
• Slow virus


  • Subacute sclerosing panencephalitis
• Herd Immunity


  Presence of immunity to a disease in most of the population
• Extent of Host Involvement


  • Local Infection
  • Systemic Infection
  • Primary Infection
  • Secondary Infection
• Subclinical or inapparent infections


  Does not cause any signs or symptoms of a disease in a host
• Predisposing Factors


  Makes the body more susceptible to disease or alters the course of a disease
• Development of Disease


  • Incubation Period
  • Prodromal Period
  • Period of Illness
  • Period of Decline
  • Period of Convalescence
• Reservoir of Infection


  • Human Reservoir
  • Animal Reservoir
  • Nonliving Reservoir (soil and water)
• Healthcare-Associated Infections (HAIs)


  Infections patients acquire while receiving treatment for other conditions at a health care facility, or in-home health care environment
• Pathogenicity


  The absolute ability of an infectious agent to cause disease in a host
• Virulence


  The ability of the pathogen to infect or damage the host