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Slide 1Slide 2Most microbes don’t cause diseaseNormal Microbial FloraDefinitionsDefinitions (Con’t)Transmission of diseaseEstablishment of disesaeEstablishment of disease (con’t)Non-specific resistance to diseaseMechanical and Chemical barriersMucus membranesBiological barriers and immune response mechanismsSlide 14Immune response mechanismsSpecific resistance and the immune systemAntigens (Ag’s ; Antibody generator)Slide 18Specific resistance and the immune system (Con’t)Specific resistance and the immune system (con’t)Cell mediated immunityAntibody mediated immunitySlide 235 different classes, each with different biological functionsImmunological memoryTypes of specific immunitySlide 27Dangerous immune responsesVaccinationVaccination (Con’t)Slide 31Viral diseases of humansChicken pox and MumpsSmallpox, Influenza, and RhinovirusViral diseases of the nervous systemPolioSlide 37Viral diseases of the organsViral diseases of the organs (Con’t)Viral diseases of the organs (Con’t)Bacterial diseases of humansAirborne diseasesSlide 43Airborne diseases (Con’t)Slide 45Foodborne and waterborne diseasesFoodborne and waterborne diseases: BotulismSlide 48Foodborne and waterborne diseases: SalmonellosisFoodborne and waterborne diseases: CholeraSoil born diseases: AnthraxSoil borne disease: Tetanus (lock jaw)Arthropod-Borne diseasesSTDSMICRO 106 FINAL EXAM NOTESCLASS NOTESINTRODUCTION TO INFECTIOUS DISEASE4-11-14Most microbes don’t cause disease•Either non-pathogens or due to host immunity•Microbes are non-pathogenic and are essential to human health•There are more microbial cells than human cells on a healthy humanNormal Microbial Flora•1. Microbial population of humans•All parts of the human body in contact with external environment are heavily colonized by microbes (e.g. skin, mouth)•More microbes in moist regions (armpits, groin)•2. Internal organs/tissues free of microbes (sterile)•3. Relationship between humans and microbes mostly positive or neutral•4. Different microbes (fungi and bacteria) occupy distinct sites of the body•Composition also changes over time and depending on environment•5. Prevent infections by out-competing or inhibiting growth of opportunistic and actual pathogensDefinitions•A. Infection: relationship between microbe and host•1. Competition between host and microbe may result in disease or resistance (e.g. normal microbial flora infect body without causing disease)•B. Pathogen: disease-causing parasite•C. Opportunistic pathogen – normally non-pathogens; become pathogenic in an immunocompromised host (e.g. Staph epi and other normal microbial flora)•D. Virulence – degree of pathogenicity (e.g. Lactobacilli are avirulent; Thyphoid bacillus is virulent)Definitions (Con’t)•E. Disease – state of “abnormal health”•1. Endemic: constant presence and limited spread in population measles)•2. Epidemic: rapid and widespread within population (flu)•3. Pandemic: worldwide spread (AIDS)•F. Carrier: individual who has recovered from disease but remains infectiousTransmission of disease•A. Two methods: direct and indirect•B. Direct contact•1. Requires physical contact between 2 hosts•Handshakes (common cold)•Aerosols (common cold, measles)•Sex (herpes, gonorrhea)•C. Indirect contact•1. Contact with contaminated water, food, or fomites (inanimate object e.g. syringes, needles, etc.)•Ex: insect or arthropod vectors (mosquitoes and malaria/yellow fever; ticks and Lyme’s disease)•Ex: water (typhoid, cholera, polio)•Ex: food (staph and E. Coli food poisoning)•Ex: needles (hepatitis, AIDS)Establishment of disesae•A. Portal of entry•Site at which pathogen enters host•Tetanus bacillus introduced into anaerobic tissue is dangerous•Harmless if eaten•B. Dose•Number of cells introduced into host•Varies dependent on pathogen and portal of entry•E.g. salmonella – few needed to get sick ; cholera – need high numbers to get diseaseEstablishment of disease (con’t)•C. Invasiveness •Ability to penetrate tissues and cause damage•E.g. pathogenicity of virulent vs. avirulent E. Coli•Depends on enzymes (collagenase)•D. Production of enzymes•E.g. coagulase production by pathogenic Staphylococci and resistance to phagocytosis•S. aureus is pathogenic and coagulase positive ; S epi is coagulase negative and non-pathogenic•E. Production of toxins•Two types of toxins: exotoxins and endotoxins•Exotoxins: are all proteins (heat sensitive) and dangerous at low concentrations•Endotoxins: part of gram-negative cell wall (heat resistant) and dangerous at high concentrations• CANNOT get endotoxin poison with staph infectionNon-specific resistance to disease•Two parts to immune system•Innate / non-specific immunity•same response to all pathogens•Adaptive / specific immunity•selective response•Non-specific resistance comprises barriers to infection:•Mechanical•Chemical•Cellular•BiologicalMechanical and Chemical barriers•First line of defense: interface w/ external environment•Skin•Protective barrier to infection•Best source of protection•Tough shell of keratinocytes•Regular shedding from body releases attacked microbes•Slightly acidic PH•Salty•Low water contentMucus membranes•Moist epithelial linings secrete mucus•Mucus traps microbes•In respiratory tract, ciliated epithelium moves trapped microbes into mouth (spit or swallow)•Low PH of stomach and vaginal tract•Lysozyme secretion: destroys peptidoglycan layer of cell wall (penicillin)•Defensins: antimicrobial polypeptides produced by many host cells•Destroy integrity of bacterial plasma membranesBiological barriers and immune response mechanisms•Biological barriers•Phagocytosis•Destruction of microbe by phagocytic white blood cells (e.g. macrophages, neutrophils)•Immune response mechanisms•Inflammation•Characterized by redness, swelling, warmth, pain•Attracts white blood cells to sites of infection•Destruction of microbes leads to pus formationIMMUNE RESPONSE MECHANISMS (CON’T)4-16-14Immune response mechanisms•Fever•Induced by pyrogens which can be exogenous (e.g. bacterial toxins or endogenous (produced by host cells in response to infection)•Higher body temperatures slows growth of pathogens•Interferons•Chemicals produced by cells in response to intracellular infection•Include antiviral responses in uninfected cells•Also activate white

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