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Principles of MicrobiologyBacterial DiseasesMycoplasma, Chlmaydial, Rickettsial DiseasesViral Diseases, Parasitic DiseasesSTD/HIV/Food Bourne DiseasesFungal Diseases/Immunocompromised Host

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History of MicrobiologyRole of Host and OrganismCharacteristics of Microorganisms:

-Bacteria -Viruses-Fungi -Rickettsia-Parasites -Mycoplasma-Chlamydia

ImmunityPrevention

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Discovery of Micro organisms

Antony van Leeuwenhoek-1676

The “Father of Microbiology”observed “little animals”first to describe the cellular

nature of living thingsfirst to see bacteria and

protozoabut did not make the

connection between the bacteria and disease

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Spontaneous Generation Disproved-Louis Pasteur-1861

pasteurizationdeveloped anthrax vaccinedeveloped rabies vaccine introduced the terms

aerobic and anaerobic in describing the growth of yeast

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Role of Microbial in Disease- Joseph Lister-Surgeon-1867

provided the first indirect evidence that microbes caused disease

postulated that microbes were a major cause of surgical infections

showed that heat sterilized instruments and carbolic acid on dogs greatly reduced post op infections.

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Role of Microbials in Disease-Robert Koch-1877

first to demonstrate that specific microbe caused disease

established the link between Bacillus anthracis and the disease

his method of proving the cause of disease now called Koch’s Postulates

23-04-21Koch’s first micrographs showing Bacillus anthracis

Microbiology in the Twentieth Centurydevelopment of sub disciplinesdiscovery of genetic systems in bacteria

and virusesdevelopment of chemotherapy to treat

infectious diseasesmolecular biology-advancement of

scientific tools/equipment (electron microscopy)

gene therapy testing and genetic engineering

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Pathogenicitythe state of producing or the ability to

produce/cause disease.

Immunityrefers to the general ability of a host to resist a

particular infection or disease.

Virulencerefers to the ability of a bacteria to cause

infection and it has two components Invasiveness- spread Toxigenicity- power /strength

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Two Major Areas:

Non-specific resistance mechanisms also called natural defenses

Acquired or Specific immunity immune response

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Four categories:General-direct and indirect barriers

Physical or mechanical barriers-first line of defence

Chemical barriers

Biological-second line of defence

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Immune Response:Reaction of the body to foreign

antigens-inflammatory response

System consisting of several immunologic mechanisms

Lymphocytes recognize and eliminate infectious agents

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Acquired Immunity: Can be naturally acquired or artificially acquired Can beeither active or passive

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Developed after exposure to an antigen or transfer of antibodies or lymphocytes from an immune donor.-naturally acquired active immunity-infection process

-naturally acquired passive immunity-placental transfer

-artificially acquired active immunity-vaccine

-artificially acquired passive immunity-antibodies produced by animal or vitro are given to host

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Host Defenses

NonspecificResistance

Chemical

Biological

GeneralDirect/indirect

Physical

Specific immunity(immune response)

AcquiredImmunity

ArtificialNatural

PassiveActive Active

Antibodies or Lymphocytes produced due

to infection

Antibodies produced by

animal orin vitro

Antibodies are passed to fetusfrom placentaor colostrum

Antibodies areproduced as a

result of immunization

Passive

Immunosuppression or deficiency-Illness

-Drugs-Radiation

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Immunotherapy-Active vs passive-Drugs

Antibody-mediated immunity or humoral (AMI)Principle immune response against

extracellular bacteria-regulated by B cells and the antibodies they produce-defends against bacteria, bacterial toxins and viruses-Helper T-Cells(CD4) and macrophages identify antigen and activate cytokines ( co-stimulators of B cells)-B Cell divides into plasma cells and B memory cells- B Cells- Plasma cell produce antibodies

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Scanning electron micrograph of human macrophage ingesting Streptococcus pyogenes. The spherical cell riding piggy-back on the macrophage is a lymphocyte, an important component in the immune response to infection.

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    1. The macrophage eats the bacteria, 2. Proteins (antigens) from the bacteria are broken down into short peptide chains,3. Those peptides are then "displayed" on the macrophage surface 4. Bacterial peptides are similarly processed and displayed on the surface of B lymphocytes5. Helper T cell stimulates B Cell to turn on antibody production.6. B Cell multiplies/enlarges and clones to be antibody secreting plasma cells, all secreting antibodies7. Antibody binds to bacteria-enables ingestion by white cells

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Cell-mediated immunity (CMI) protective immune response against

intracellular bacteria-controlled by T cells (3 types) -cells infected by viruses/bacteria in the body- trigger proliferation and differentiation of T Cells -protect against parasites, fungi, etc, can also kill cancerous body cells

Three types Migrate from red bone marrow to the thymus

Helper CD4 T cells

Killer CD8 T Cells Cytotoxic

Memory Left over from previous infection, these allow for

swifter response to same antigen in the future.

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T-Killer lymphocyte recognizes surface markers on cells and labels them for destruction

T-lymphocyte attacking and killing a much larger influenza virus. Time elasped-30min.

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Inflammatory responseTriggered by physical biological or chemical

agentsVasodilation of the capillariesPermeability allowing protein rich exudate to

move in to the affected area (neutrophils, macrophages)

Emigration of leukocytes into the affected areaChemotaxis mediators released by damaged

tissue draw leukocytesPhagocytosis engulf bacterium

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Complement SystemSystem of approx 20 protiens produced in liver

and collectively called complement they facilitate actions of antibodies

4 major functionsMark an invader/antigens for phagocytosisTarget cytolysis – membrane attack complexSupplements inflammatory responseWorks with immune response

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Invasiveness

ToxigenicityExotoxinsEndotoxins

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ability to adhere, multiply and spreadTransport to host

direct/indirect contact, vectors and fomites

Attach and colonizerequires adherence factors or adhesions

Invade the hostproduction of lytic substances, enzymes, or

other products. Grow and reproduce

find appropriate environment. Some very specific, eg: specific tissues or blood plasma-receptors 23-04-21

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Exotoxins3 Catagories; neurotoxins, enterotoxins, and

cytotoxins.Ability to produce toxic substances Bacterial protein (often enzymes) excreted by

growing bacteria. highly toxic and often fatalTarget cell specific. Both gram + and – bacteria Does not usually produce feverHighly antigenic: formation of antitoxinsBotulism, tetanus, diphtheria

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Endotoxinspart of cell wall of gram -bacteria, is liberated when cell wall

disintegrates. weakly toxic and will usually produce fever,

diarrhea, vomiting. do not convert into toxoidslarge doses can cause death-hemorrhagic shock

and tissue necrosisHeat stable

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Bacterial type Gram-negative bacteria Many Gram positive bacteria, some gram negative bacteria

Cellular location Lipopolysaccharide region of wall Cytoplasm (inside the cell)

Chemical structure Lipid portion of the lipopolysaccharide

Proteins

Heat stable Stable Unstable

Toxicity Low High

Representative symptoms Flu-like illness, fever, inflammation, fatigue, respiratory distress, septic

shock, nausea 

Cell & tissue necrosis (death), neurological effects, severe

dehydration

Representative diseases Septic shock, humidifier disease, organic dust toxic syndrome 

Botulism, cholera, diphtheria, tetanus, bubonic plague, food

poisoning

Characteristic Endotoxin Exotoxin

A Comparison of Endotoxins & Exotoxins

Procaryotic“pro”=before,+”karyos”

nucleuslack a true nucleusmost bound by chemically

complex cell wall grow very rapidlytypical sizes: 1 um

diameterincludes bacteria, viruses

and archaeobacteria

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Eucaryotic

•“eu”=true, + “caryos”=nucleus• membrane-enclosed nucleus• complex DNA• complex processes-phagocytosis, ameboid movement• includes: protists, fungi, animals and plants • typical size: 5 micrometers (yeast cells) to 50 or 100 micrometers

Size: most range from

0.25 to 3. micron (µm) in diameter

0.5 to 5 µm in length

Spirochetes can reach up to 20µm

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Shape or morphology:

Coccus (sphere)Bacillus (rod)Spiral, spirochete

(flexible corkscrew)

Vibrio (comma-shape)

Pleiomorphic (variable in shape)

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Strep

Pseudomonas

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Arrangements:

Single cell

Double cells (diplo-)

Packets of four (tetrads)

Grape-like clusters (staphylo-)

Chains (strepto-)

Single cells side to side (palisade)

Capsule/Cell Wall-most bacteria except one group

-used for identifying and classifying-made of peptidoglycan-important for identifying Gram- or Gram +

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External Appendages:Flagella-long

filaments

Pili (fimbriae)-protein fibers

Conjugation or Sex pilus-hollow tubes to transfer DNA

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Reproduction:

Chiefly by binary fission

Nutritional requirements

Affected by environmental factors

Short doubling time

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Staphylococcus aureus have gone through 2 cell

divisions, producing a pair of tetrads. This can happen every 20-30min

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LAG PHASE: Growth is slow at first 

LOG PHASE: they start multiplying exponentially, doubling in number every few minutes. STATIONARY PHASE: As more and more bugs are competing for dwindling food and nutrients, booming growth stops and the number of bacteria stabilizes. DEATH PHASE: Toxic waste products build up, food is depleted and the bugs begin to die.

Survivability:Can be destroyed by

heat, light, ionizing radiation

Spores are extremely resistant to destruction

AntisepticsBacteriostaticsBacteriocidalsAntibiotics 23-04-21

Macrophage enveloping Candida albicans

Metabolic requirements:

NutrientsOxygen

-aerobes, anaerobesTemperature

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Enzyme ProductionCoagulases,

Hemolysins-promote spread

Proteases, lipases-provide nutrients

Protective enzymes-penicillinase

Toxins/gasses/pigments

Endotoxins and exotoxins can cause local or systemic effects.

Toxoids-confer immunity

Gasses-clostridiaPigments-

Pseudomonas

                                                       

AirbornePhysical contact

-fomitesSecretions

-universal precautionsFood/water borne

-epidemicsAnimals/insects

-zoonoses-vectors-parasites, etc

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The bacterium borrelia burgdorferi is responsible

for Lyme disease.

MicroscopyDark field-unstained

cells, hanging dropPhase contrast-good

for endospores or eucaryotic cells

Fluorescence-use fluorochromes, orange or green

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Staining: differentialGram’s stain

-divides bacteria into two classes-Gram positive-staph, strep-Gram negative-hemophilus, neisseria

Acid Fast-mycobacterium

-tuberculosis-leprosy

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Culture-in vivo(in living body)

-in vitro (outside living

body, test tube)

-sensitivity (C&S)

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Pseudomonas

Systemic or topical

Bacteriocidal (kill)-penicillins, cephalosporins

Bacteriostatic (inhibit)-tetracyclines, erythromycin, sulfonamides

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Mode of Action:Inhibition of cell

wall synthesisDestruction of cell

wallInhibition of

bacterial protein synthesis

Inhibition of other bacterial metabolism

Drug Resistance23-04-21

Virion-a complete virus particle

Smallest microorganisms

Nucleic acid core-DNA or RNA

Parasitic-wholly dependant for reproduction

Visible by electron microscope

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Composition

-Nucleic Acid-DNA or RNA-Single or double stranded, linear or circular-Coat of proteins called a capsid-Extensions called antigens-Not classified as alive or dead-strictly parasitic-they are acellular

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HIV belongs to a special group of viruses, called "retroviruses." Its genetic information is not encoded as DNA, but instead as RNA (ribonucleic acid) and therefore has to be reverse transcripted into DNA.

Morphologyfour general shapes

helical – a spiralpolyhedral – many surfacesbinal - are neither helical or polyhedral,

are pelomorphic or irregular enveloped – membrane surrounding the capsid

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.

Three different types of viruses

Plant, animal, and bacterial or DNA, RNA and Reverse Transcriptase

Viruses are cell specific (i.e.) Virus that enters the lungs, but is specific to the stomach, would cause no harm

Very specific method of entry

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This may look like a space capsule, but it's actually a virus. The top part is the capsid, the body is the sheath, and the tails at the bottom help the virus attach to its host

Enveloped virus-Herpes simplex virus (HSV6, DNA virus) on a peripheral blood lymphocyte

T4 bacteriophage (DNA virus).

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Herpes Simplex-envelope Bacteriophagic-binal

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Absorption and penetration of cell membrane

LatencyReplicationCytotoxicity

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ChemotherapyHinder intracellular

replicationAcyclovir for HerpesAmantidine for

InfluenzaImmunotherapy

Acute infectionProphylaxis-vaccination

Role of antibiotics

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This innocent-looking virus causes the often-

deadly Ebola hemorrhagic fever.

Intracellular parasiteCoccoid, gram-neg

bacteriaHave both RNA &

DNAThree species-

-C. trachomatis

-C. psittaci-C. pneumoniae

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Elementary body C. trachomatis

Culturing very expensive & time consuming

Sero-diagnosis method of choice-if sufficient antigen

Antigen-detection methods. -enzyme immunoassays (EIA) -direct fluorescence assays (DFA)

Molecular amplification tests best-no special methods

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membrane-bound vacuole

Intracellular parasite

Coccoid, gram-neg bacteria

Induces phagocytosis to enter cells

Three species- -R. prowazekii-R. Typhi-R. rickettsii

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Rickettsia rickettsii in endothelial cells of a blood vessel from a patient with fatal RMSF

Indirect fluoresent antibody staining

Special staining requiredSerological:-Weil Felix reaction test-Complement Fixation Test

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Gram negativeSpiral, slender, long

bacteriaVery mobile-axial

filamentCan be free living or

parasiticThree genus:

-Treponema

-Leptospira

-Borrellia

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T. pallidum - human syphilus - ("For one small pleasure I suffer a thousand misfortunes")

Diagnosis:

-clinical presentation

-geographical location-serological tests

-VDRL, agglutination-darkfield microscopy of lesions & silver staining-cultures

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Note: axial filament

Characteristics:Lack cell wallsVary in shapeSmallest bacteria capable

of reproductionExtracellular parasiteDiagnosis:

-enzyme immunoassay-cultures take 1-3 weeks-x-Ray

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Eucaryotic, spore bearing

Plant like organisms-lack chlorophyll

Few are pathogenicOpportunisticDiseases in humans-

mycoses4 Divisions

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Disease(s):Blastomycosis

Skin lesion following dissemination from the lungs.

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Classification by Disease PresentationCutaneous Mycoses    Dermatophytoses        Microsporum        Trichophyton        Epidermophyton

    Superficial Mycoses        Tinea nigra        Piedra        Tinea versicolor

Subcutaneous Mycoses    Chromoblastomycosis    Mycetoma    Sporotrichosis Systemic Mycoses    Histoplasmosis    Blastomycosis    Coccidioidomycosis    Yeast infection    Phycomycoses        Rhizopus        Mucor        Aspergillus

Diseases:Dermatophytes-Skin

-Body ringworm -Scalp ringworm

Candidiasis-Thrush -Vaginal Candida infections

Mycosis -histoplasmosis-blastomycosis

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Genus:Candida Species: albicans

This human macrophage is a professional "phagocyte" or eating cell (phago = "eating", cyte = "cell"). The macrophage is using its internal cytoskeleton to envelop cells of the fungus Candida albicans.

Diagnosis:Clinical presentation-impLaboratory

Investigationsmicroscopic

visualizationSerological test-blood

cultureEnsure good

specimens takenLung biopsyBroncho specimentsUrine by catheter

23-04-21Disease(s):Histoplasmosis

Organisms that live within upon or at the expense of another, do not contribute to survival of host.

Classification:Protozoa

-unicellularMetazoa

-multicellularReproduction-by binary fission and sexual

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Classification:Protoza-unicellular-Amoeba-Pneumocystis carinii-Plasmodia-Toxoplasma-Giardia

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Toxoplasma gondii in the bronchoalveolar lavage material

Giardia intestinalis in culture.

Classification:Metazoa-Helminths-Nemotodes (round

worms)-6 different types

-trichemosis-filavasis-pinworm-roundworm-hookworm-whipworm

-multicellular, larger than protoza

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Metazoa-Helminths

-Cestodes (tapeworms)-Taenia-beef & pork worm can be up to 10 meters long

-Trematodes (flukes)-Schistosomiasis-swimmer’s itch-Clonorchissis-liver fluke

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Trichomonas vaginalis from culture. The four flagella and single nucleus are visible. The dark median rod is the axostyle which is characteristic of the trichomonads; approximate size = 26 µm.

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Acarus scabei-scabies

Pediculi-capitis-corporis-pubis

Fleas-the human flea is an endangered species-rat flea-plague

http://www.biosci.ohio-state.edu/~parasite/pictures/scabies_mite.gif

Depends on patient-pathogen interaction

Local effects-due to inflammation

-blood vessels dilate-skin red, warm-capillaries in area permeable-fluid in-swelling-chemicals released-pain-neutrophiles, etc.

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Neutrophils are our body's first line of defense against bacterial infections. After leaving nearby blood vessels, these cells recognize chemicals produced by bacteria in a cut or scratch and migrate "toward the smell".

Systemic effects-malaise, myalgia

-fever, chills, rigors-tachycardia-shock-leukocytosis, increased ESR-maybe absent in immune deficient patient-differ in severity from patient to patient

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Fever:-normal body temp-site taken-fever patterns-temp above 37.8 C is a cardinal sign

Causes-pyrogens-exotoxins and endotoxins-virus particles

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FeverChills

-thermoregulatory set point-increased muscle activity

Sweats-defervescence

(subsidence of fever to normal)

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The neutrophil is the main cell to mediate the effects of acute inflammation High-magnification of pus in the lumen of the appendix. Pus consists of living and degenerate neutrophil polymorphs together with liquefied tissue debris.

FeverDifferential Diagnosis

-infection -Trauma-Thyrotoxicosis -MI-Dehydration -Malignancy

Treatment-reason to treat fever-antipyretics-ASA, Acetaminophen, etc.

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FeverSystemic ManifestationsLeukocytosis-WBC over 11,000-nonspecific for infection-differential-left shift -neutrophilia-bacterial infection-eosinophilia-parasitic infection or allergy-lymphocytosis-viral illness -monocytosis-TB, protozoal infection

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Barriers-universal precautions (standard)-Isolation procedures

Prophylaxis-exogenous pathogens

-traveller’s diarrhea, meningitis, malaria-normal flora

-immunocompromised patients-surgical

-wound debridement

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Active immunization-administration of an antigen of low (attenuated) virulence-stimulates cell-mediated and humoral immunity

Passive immunization-administration of antibodies-gamma globulins-HBIG, HZIG

Toxoid-denatured toxin-DPT

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Toxoid-tetanus/diphtheria

Killed Bacteria-cholera, meningococcal, typhoid

Attenuated Bacteria-typhoid, BCG

Attenuated Virus-MMR, polio(oral), yellow fever

Killed Virus-polio(salk), Hep B, influenza

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Study of distribution and determinants of health-related conditions or events

Application of this study to control health problems

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Study Mathematical

Statistics Probability

Development and testing of hypotheses Observation Use of scientific methods

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• The traditional model of infectious disease causation. Includes three components: an external agent, a susceptible host, and an environment that brings the host and agent together, so that disease occurs.

Disease Origins:The epidemiological model

Susceptible HostSupportive Environment

Virulent Agent

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Application of Epidemiological Triad

Host – described as any susceptible human being (age, sex, ethnicity, etc.)Age- high risk age men 18 – 30 years. Older workers with diminished sensory abilities, effects of chronic illness, and delayed reaction times. Women in child-bearing years. Individuals hypersensitive to chemicals, compromised immune system, sun exposure, hypertensive, etc. 

Agents – factors association with illness and injury, are occupational exposures that are classified as biologic, chemical, ergonomics, physical, or psychosocial

Environment – includes all external conditions that influence the interaction of host and agents. These may include workplace conditions such as temperature extremes, shift work, and inflexible management styles. New environmental problems: wastes and toxins and indoor and outdoor environmental pollution. A soldier may be required to have protective clothing, and work in a hot and humid environment. As the worker becomes uncomfortable in the hot clothing, rolling up a sleeve, taking off a glove, or wiping his/her face with a contaminated piece of clothing may compromise his/her protection. Norms in the workplace may condone such work practices, but “Everyone is doing it

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The continuing process of scrutiny of all aspects of occurrence and spread of a disease.

Systematic collection, analysis, interpretation, and dissemination of health data on an ongoing basis

Passive SurveillanceActive SurveillanceSurveillance is information for action

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What does it consist of:

Morbidity and mortality reportsReports of field investigationIsolation and ID of infectious agents by labsData concerning the availability, use and effects

of immunizing agents and other control substances

Immunity levels in segments of populationReport with above data prepared and

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Case Reports-provide minimal identifying data.

Name, address, age, genderAddressDiagnosisDate of report of each patientDates of onsetBasis for diagnosis

Remember right of privacy

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Herd immunity: the immunity of a group or community. The resistance of a group to invasion and spread of an infectious agent.

Reservoir: person, animal, etc in which an infectious agent normally lives and multiplies.

Endemic: the constant presence of a disease or infectious agent within a given geographic area.

Epidemic: the occurrence in a community or region of cases of an illness/outbreak with a frequency clearly in excess of normal expectancy. The number of cases indicating presence will vary with the infectious agent, size and type of population exposed.

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Pandemic: is an increase in disease occurrence within a large population over a very wide region, usually continents.

Host: a person, etc. that affords subsistence to an infectious agent under natural conditions.

Carrier: a person, etc. that harbors a specific infectious agent without discernible clinical disease and serves as a potential source of infection.

Fomite: indirect contact with anything (clothes, utensils, etc.) that belongs to an infected person where bacteria can survive

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Vector: living transmitters of a pathogen, most are arthropods or vertebrates.

Pathogenicity: the power of an organism to produce disease.

Organism: any living thing plant or animal, maybe unicellular or multicellular.

Virulence: the degree of pathogenicity of an infectious agent, indicated by case-fatality rates and/or the ability of the agent to invade and damage tissues.

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Communicable disease: illness due to a specific infectious agent or its toxic products that arises through transmission of that agent of its products from an infected person, etc to a susceptible host; either directly or indirectly.

Communicable period: the time during which an infectious agent may be transferred directly or indirectly from an infected person to another person. Can be short or very long.

Incubation period: the time interval between initial contact with an infectious agent and the first appearance of symptoms associated with the infection.

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Questions????

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