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Intro to-immunity-with-narration

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  • 1.
    • Host-microbe relationships
    • Disease processes
    • Epidemiology
    • Nosocomial infections
    Introduction to Immunity
  • 2. Host-Microbe Relationships
    • What do the following terms mean?
    • Pathogen
    • Host
    • Symbiosis
      • Symbiosis includes:
        • mutualism
        • commensalism
        • parasitism
  • 3. Example of Mutualism: Bacteria on The Human Skin
  • 4. Contamination, Infection, & Disease
    • Contamination : the presence of microbes
    • Infection : the multiplication of any parasitic organism in or on a host
    • Disease : a change in the state of health in which tissues/organs are disrupted or damaged.
    • Can be viewed as a sequence of increasing severity (contamination infection disease)
  • 5. Pathogenicity vs. Virulence
    • Pathogenicity : the ability of an organism to cause disease
    • Virulence : the intensity (or degree) to which an organism causes disease
  • 6. Microflora (Flora, Microbiota)
    • Organisms that live on or in the body but under normal circumstances do not cause disease
    Types: Resident microflora (normal flora): comprise microbes that are always present in or on the human body Transient microflora: microbes that can be present under certain conditions in any of the locations where resident microflora are found
  • 7. Opportunistic Organisms
    • Organisms that do not normally cause disease, but take advantage of particular opportunities to cause disease.
    • Immunocompromised individuals commonly become infected with opportunistic organisms
  • 8. Kinds of Diseases
    • Human diseases are caused by infectious agents, structural or functional genetic defects, environmental factors, or any combination of these causes
    • Infectious Diseases: caused by infectious agents such as bacteria, viruses, fungi, protozoa, & helminths
    • Noninfectious Diseases: caused by any factor other than infectious organisms
  • 9. Microbiology focuses on Infectious Diseases
    • Communicable disease : a disease that can be transmitted from one person to another
    • What are examples of communicable microbial diseases?
    • Noncommunicable disease : a disease that cannot be transmitted from one person to another
    • What are examples of noncommunicable microbial diseases?
  • 10. Types of Infectious Diseases
    • Acute : develops rapidly & runs its course quickly (measles & cold)
    • Chronic : develops more slowly than an acute disease, is usually less severe, & persists for a long, indeterminate period (tuberculosis)
    • Subacute : intermediate between an acute & a chronic disease (gingivitis)
    • Latent : characterized by periods of inactivity either before signs & symptoms appear (herpes virus)
  • 11. Stages of an Infectious Disease
    • Incubation period: time between infection & appearance of signs and symptoms
    • Prodromal phase: a short period of nonspecific, often mild, symptoms (malaise and headache)
    • Invasive phase: period when the individual experiences the typical signs & symptoms of the disease
    • Acme : period during invasive phase where
    • symptoms & signs are most severe
    • Decline phase: the period of illness when host defenses & effects of treatment overcome the pathogen
    • Convalescent period: tissues are repaired, healing takes place, & body regains strength & recovers
  • 12. Stages of an Infectious Disease
  • 13. Signs, Symptoms, & Syndromes
    • Most diseases are recognized by signs & symptoms
    • Sign : a characteristic of a disease that can be observed by examining the patient (e.g. swelling, redness, rashes, coughing, pus, runny nose, vomiting)
    • Symptom : a characteristic of a disease that can be observed or felt only by the patient (e.g. pain, shortness of breath, nausea, sore throat, headache)
    • Syndrome : a combination of signs & symptoms occurring together & are indicative of a particular disease or abnormal condition
    • Sequelae : even after recovery, some diseases leave after-effects (e.g. valve damage)
  • 14. Epidemiology, Incidence & Prevelance
    • Epidemiology : the study of factors & mechanisms involved in the frequency & spread of diseases & health-related problems
    • Etiology : the assignment or study of causes and origins of a disease
    • Incidence of a disease: the number of new cases contracted within a set population during a specific period of time
    • Prevalence of a disease: the total number of people infected within the population at any time
  • 15. Diseases in Populations
    • Endemic : disease is present continually in the population of a particular geographic area
    • Epidemic : a higher-than-normal incidence of a disease in a population
    • Pandemic : worldwide disease
  • 16. The Spread of Cholera
    • Began in Peru in 1991
    • Moved to Columbia & Ecuador
    • Late 1992: epidemic spread to Venezuela, Bolivia, Chile, & Brazil in South America
    • Then to Guatemala, Honduras, Panama, Nicaragua, & El Salvador in Central America
  • 17. Reservoirs of Infection
    • Reservoirs: Sites in which organisms can persist & maintain their ability to infect
    • Essential for new human infections to occur
      • Humans
      • Other animals (including insects)
      • Plants
      • Certain nonliving material (water & soil)
    • Zoonoses: diseases that can be transmitted under natural conditions to humans from other vertebrate animals (rabies)
  • 18. Modes of Disease Transmission- Contact Transmission
    • direct contact
    • indirect contact (fomites)
    • droplets
  • 19. Modes of Disease Transmission- Vehicle transmission
      • water
      • air
      • food
  • 20. Droplet Transmission
  • 21.
    • Modes of Disease Transmission- Vector transmission
      • mechanical
      • biological
  • 22. Controlling Disease Transmission
    • Isolation : A patient with a communicable disease is prevented from having contact with the general population
    • Quarantine : the separation of “healthy” human or animal carriers from the general population when they have been exposed to a communicable disease
  • 23.  
  • 24. Modes of Disease Transmission- Summary
    • Contact Transmission
      • Can be direct, indirect, or by droplets
      • Direct contact requires body contact between individuals
      • Indirect contact occurs through fomites
      • Droplet: occurs when a person coughs, sneezes, or speaks near others
    • Vehicle Transmission
      • Nonliving carrier of an infectious agent from its reservoir to a susceptible host
      • Water
      • Air
      • Food
    • Vector-Borne Transmission
      • Vectors: Living organisms that transmit disease to humans
      • Most vectors are arthropods: ticks, flies, fleas, lice & mosquitoes
  • 25. How Fungi & Protozoa Cause Disease
    • Fungi
    • Spores that are inhaled or enter cells through a cut or wound
    • Some fungi produce mycotoxins
    • Protozoa
    • invade & reproduce in red blood cells
    • attach to tissues & digest them
    • Produce cysts (dormant forms) as a means of disease transmission & trophozoites (active, multiplying forms)
  • 26. Factors Affecting Disease Establishment
    • Portal of Entry
    • Adhesive Factors
    • Dose
    • Tissue Penetration
    • Enzymes
    • Toxins
      • Toxins, enzymes, & adhesive factors are sometimes referred to as virulence factors
  • 27. Portal of Entry
    • Site of entry of microbes
      • Includes skin, mucous membranes, openings of the respiratory, digestive, & genitourinary systems, & crossing the placenta
    • May involve adhesive factors, also known as adhesins (include certain surface proteins/ glycoproteins, fimbriae, & capsules)
  • 28. Portals of Exit sites where microbes leave the body
  • 29. Dose
    • The number of infective particles required to lead to colonization
    • Colonization refers to the growth & reproduction of microorganisms on host tissues
    • Exposure to a low dose can result in immunity
  • 30. Tissue Penetration
    • The ability of a microbe to enter host tissue
    • Visible in tissue preparation
    • Not required for every disease
    • The ability of a microbe to invade tissue & damage it is known as its invasiveness
  • 31. Enzymes
    • Coagulase
    • Streptokinase
    • Hyaluronidase
    • Hemolysins
    • Leukocidin
    • Collagenase
  • 32. Coagulase : clots fibrin in blood plasma. Bacteria form a fibrin clot around themselves protecting them the host’s immune system ( S. aureus ) Streptokinase : dissolves fibrin clots ( Streptococcus ) Enzymes
  • 33. Hyaluronidase: enzyme digests hyaluronic acid Enzymes
  • 34. Hemolysins: enzymes that breakdown red blood cells (RBCs) 3 Types of hemolysis : 1- Gamma hemolyis : no breakdown of RBCs 2- Alpha (  ): partial breakdown of RBCs; greenish-grey coloration 3- Beta or complete hemolysis (  ): complete breakdown of RBCs; clear zones around colonies Alpha Beta Streptococcus pneumoniae Streptococcus pyogenes Enzymes
  • 35. Enzymes
    • Collagenase : enzyme that degrades collagen ( Clostridium )
    • Leukocidin : enzyme that degrades white blood cells
  • 36. Bacterial Toxins
    • A substance that is poisonous to another organism
    • Two types:
      • Exotoxin : a toxin produced by a cell & is secreted outside the cell to affect host tissue
      • Endotoxin : a toxin that is a portion of the cell (usually the cell wall) & is released into host tissues
        • Characteristic of Gram negative bacteria
  • 37. Nosocomial Infections : a n infection acquired in a hospital or other medical facility Where do the bacteria causing nosocomial infections come from? Common Causative Agents of Nosocomial Infections
  • 38. Some Common Modes of Transmission of Nosocomial Infections
  • 39. Relative Frequencies of Sites of Nosocomial Infections
  • 40.
    • Latex gloves
    • Eye protection
    • Mask
    • Sterile Equipment
    Infection Control