Epidemiology and Disease How are diseases transmitted and acquired?Important DefinitionsNormal Microbiota and the Host:Slide 4Slide 5Koch’s PostulatesSlide 7Classifying Infectious DiseasesSlide 9Frequency and Occurrence TerminologySeverity or Duration of a DiseasePredisposing FactorsSlide 13Transmission of DiseaseSlide 15Slide 16Nosocomial (Hospital-Acquired) InfectionsRelative frequency of Different Nosocomial InfectionsTop Nosocomial Pathogens Causing Hospital Associated InfectionsThe Inanimate Environment Can Facilitate TransmissionSlide 21The Stages of a DiseaseReservoirs of InfectionSlide 24Emerging Infectious DiseasesSlide 26Slide 27Gaining a Foothold: Mechanisms of PathogenicityEnzymes That Break Down Host CellsSlide 30Toxins: Two TypesEndotoxinEndotoxins Produce Fever, Chills, Weakness, ShockExotoxin ExamplesExotoxins Have Different EffectsExotoxin TypesExamples of ExotoxinsSlide 38Cytopathic and Pathogenic Properties of Viruses and FungiSlide 40Epidemiology and Disease How are diseases transmitted and acquired?•Microbial interactions•Microbial antagonism•Opportunistic infections•Proving the cause (etiology) of a disease•Koch’s Postulates•Classifying Disease•Symptoms and signs•Communicable and contagious•Incidence, sporadic, endemic, epidemic, pandemic•Acute/chronic, local vs systemic, bacteremia/septicemia/viremia•The Spread of Infection•Contact Transmission: direct vs indirect•Vehicle Transmission•Vectors (live non-human carriers)•Nosocomial infections; protection•The Course of a Disease•Incubation, prodromal, illness, decline, convalescence periods•Tracking diseases: Epidemiology•CDC (Atlanta, GA), WHO of the UN (Geneva, Switzerland)•Mechanisms of Pathogenicity: Disease Stages, Toxins, Cytopathic EffectsThe study of disease transmission and origin is called epidemiology and it seeks to determine the index case.Important Definitions•PathologyStudy of disease•Etiology Study of the cause of a disease•Pathogenesis Development of disease•Infection Colonization of the body by pathogens•Disease An abnormal state in which the body is not functionally normallyFigure 14.2•Locations of normal microbiota on and in the human bodyNormal Microbiota and the Host:•Transient microbiota may be present for days, weeks, or months•Normal microbiota permanently colonize the host•Symbiosis is the relationship between normal microbiota and the host•Commensalism is when the bacteria benefit but the host (us) neighter benefits or is harmed•Microbial antagonism is competition between microbes. •Normal microbiota protect the host by: •occupying niches that pathogens might occupy•producing acids•producing bacteriocins•Probiotics are live microbes applied to or ingested into the body, intended to exert a beneficial effect.Normal Microbiota and the Host:Epidemiology and Disease How are diseases transmitted and acquired?•Microbial interactions•Microbial antagonism•Opportunistic infections•Proving the cause (etiology) of a disease•Koch’s Postulates•Classifying Disease•Symptoms and signs•Communicable and contagious•Incidence, sporadic, endemic, epidemic, pandemic•Acute/chronic, local vs systemic, bacteremia/septicemia/viremia•The Spread of Infection•Contact Transmission: direct vs indirect•Vehicle Transmission•Vectors (live non-human carriers)•Nosocomial infections; protection•The Course of a Disease•Incubation, prodromal, illness, decline, convalescence periods•Tracking diseases: Epidemiology•CDC, WHO•Mechanisms of Pathogenicity: Disease Stages, Toxins, Cytopathic EffectsThe study of disease transmission and origin is called epidemiology and it seeks to determine the index case.•Koch's Postulates are used to prove the cause of an infectious disease.Koch’s PostulatesGood exam questionEpidemiology and Disease How are diseases transmitted and acquired?•Microbial interactions•Microbial antagonism•Opportunistic infections•Proving the cause (etiology) of a disease•Koch’s Postulates•Classifying Disease•Symptoms and signs•Communicable and contagious•Incidence, sporadic, endemic, epidemic, pandemic•Acute/chronic, local vs systemic, bacteremia/septicemia/viremia•The Spread of Infection•Contact Transmission: direct vs indirect•Vehicle Transmission•Vectors (live non-human carriers)•Nosocomial infections; protection•The Course of a Disease•Incubation, prodromal, illness, decline, convalescence periods•Tracking diseases: Epidemiology•CDC, WHOThe study of disease transmission and origin is called epidemiology and it seeks to determine the index case.Classifying Infectious Diseases•Symptom A change in body function that is felt by a patient as a result of disease (e.g. pain)•Sign A change in a body that can be measured or observed as a result of disease (e.g. body temperature).•Syndrome A specific group of signs and symptoms that accompany a disease (e.g. AIDS, SARS).Classifying Infectious Diseases•Communicable disease A disease that can be spread from one host to another (e.g. measles).•Contagious disease A disease that is easily spread from one host to another (e.g. colds).•Noncommunicable disease A disease that is not transmissable from one host to another (e.g. non-viral cancer, heart disease).Frequency and Occurrence TerminologyMay, 2008Pandemic•Acute disease Symptoms develop rapidly (e.g. influenza)•Chronic diseaseDisease develops slowly or is ongoing (e.g. bacterial vaginitis, atherosclerosis)•Latent disease Disease with a period of no symptoms (e.g. AIDS)Severity or Duration of a Disease•Make the body more susceptible to disease•Short urethra in females•Inherited traits (e.g. sickle-cell gene)•Climate and weather•Fatigue•Age•Lifestyle•ChemotherapyPredisposing FactorsEpidemiology and Disease How are diseases transmitted and acquired?•Microbial interactions•Microbial antagonism•Opportunistic infections•Proving the cause (etiology) of a disease•Koch’s Postulates•Classifying Disease•Symptoms and signs•Communicable and contagious•Frequency and occurrence terminology•Acute/chronic, local vs systemic, bacteremia/septicemia/viremia•The Spread of Infection•Contact Transmission: direct vs indirect•Vehicle Transmission•Vectors (live non-human carriers)•Nosocomial infections; protection•The Course of a Disease•Incubation, prodromal, illness, decline, convalescence