2016-03-22
 Principles of Microbiology
 Bacterial Diseases
 Mycoplasma, Chlmaydial, Rickettsial Diseases
 Viral Diseases, Parasitic Diseases
 STD/HIV/Food Bourne Diseases
 Fungal Diseases/Immunocompromised Host
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 History of Microbiology
 Role of Host and Organism
 Characteristics of Microorganisms:
-Bacteria
-Fungi
-Parasites
-Chlamydia
-Viruses
-Rickettsia
-Mycoplasma
 Immunity
 Prevention
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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 things
 first to see bacteria and
protozoa
 but did not make the
connection between the
bacteria and disease
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Spontaneous Generation
Disproved-Louis Pasteur1861
 pasteurization
 developed anthrax vaccine
 developed rabies vaccine
 introduced the terms aerobic
and anaerobic in describing
the growth of yeast
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Role of Microbial in Disease- Joseph ListerSurgeon-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 Koch1877
 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
Koch’s first micrographs showing Bacillus anthracis
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Microbiology in the Twentieth Century
 development of sub disciplines
 discovery of genetic systems in bacteria and
viruses
 development of chemotherapy to treat
infectious diseases
 molecular biology-advancement of scientific
tools/equipment (electron microscopy)
 gene therapy testing and genetic engineering
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Pathogenicity
 the state of producing or the ability to produce/cause
disease.
Immunity
 refers to the general ability of a host to resist a particular
infection or disease.
Virulence
 refers 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 be
 either 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
Specific immunity
(immune response)
Nonspecific
Resistance
General
Direct/indirect
Acquired
Immunity
Natural
Artificial
Physical
Active
Passive
Active
Passive
Chemical
Biological
Antibodies or
Lymphocytes
produced due
to infection
Antibodies are
passed to fetus
from placenta
or colostrum
Antibodies are
produced as a
result of
immunization
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Antibodies
produced by
animal or
in vitro
Immunosuppression or deficiency
-Illness
-Drugs
-Radiation
Immunotherapy
-Active vs passive
-Drugs
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 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 lymphocytes
5. 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
antibodies
7. 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
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 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 response
 Triggered by physical biological or chemical agents
 Vasodilation of the capillaries
 Permeability allowing protein rich exudate to move
in to the affected area (neutrophils, macrophages)
 Emigration of leukocytes into the affected area
 Chemotaxis mediators released by damaged tissue
draw leukocytes
 Phagocytosis engulf bacterium
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 Complement System
 System of approx 20 protiens produced in liver and
collectively called complement they facilitate actions of
antibodies
 4 major functions
 Mark an invader/antigens for phagocytosis
 Target cytolysis – membrane attack complex
 Supplements inflammatory response
 Works with immune response
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 Invasiveness
 Toxigenicity
 Exotoxins
 Endotoxins
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ability to adhere, multiply and spread
 Transport to host
 direct/indirect contact, vectors and fomites
 Attach and colonize
 requires adherence factors or adhesions
 Invade the host
 production of lytic substances, enzymes, or other
products.
 Grow and reproduce
 find appropriate environment. Some very specific, eg:
specific tissues or blood plasma-receptors
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Exotoxins
 3 Catagories; neurotoxins, enterotoxins, and cytotoxins.
 Ability to produce toxic substances
 Bacterial protein (often enzymes) excreted by growing
bacteria. highly toxic and often fatal
 Target cell specific. Both gram + and – bacteria
 Does not usually produce fever
 Highly antigenic: formation of antitoxins
 Botulism, tetanus, diphtheria
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Endotoxins
 part 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 toxoids
 large doses can cause death-hemorrhagic shock and
tissue necrosis
 Heat stable
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Characteristic
Endotoxin
Exotoxin
Gram-negative bacteria
Many Gram positive bacteria, some
gram negative bacteria
Lipopolysaccharide region of wall
Cytoplasm (inside the cell)
Lipid portion of the
lipopolysaccharide
Proteins
Stable
Unstable
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
Bacterial type
Cellular location
Chemical structure
Heat stable
Toxicity
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A Comparison of Endotoxins & Exotoxins
 Procaryotic
 “pro”=before,+”karyos” nucleus
 lack a true nucleus
 most bound by chemically
complex cell wall
 grow very rapidly
 typical sizes: 1 um diameter
 includes 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
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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 (commashape)
 Pleiomorphic
(variable in shape)
Pseudomonas
Strep
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Arrangements:
 Grape-like clusters
 Single cell
 Double cells (diplo-)
 Packets of four
(tetrads)
(staphylo-)
 Chains (strepto-)
 Single cells side to side
(palisade)
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 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
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.
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Survivability:
 Can be destroyed by heat,





light, ionizing radiation
Spores are extremely
resistant to destruction
Antiseptics
Bacteriostatics
Bacteriocidals
Antibiotics
Macrophage enveloping
Candida albicans
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Metabolic requirements:
 Nutrients
 Oxygen
-aerobes, anaerobes
 Temperature
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Enzyme Production
Toxins/gasses/pigments
 Coagulases, Hemolysins-
 Endotoxins and exotoxins
promote spread
 Proteases, lipasesprovide nutrients
 Protective enzymespenicillinase
can cause local or
systemic effects.
 Toxoids-confer immunity
 Gasses-clostridia
 Pigments-Pseudomonas
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 Airborne
 Physical contact
-fomites
 Secretions
-universal precautions
 Food/water borne
-epidemics
 Animals/insects
-zoonoses
-vectors
-parasites, etc
The bacterium borrelia
burgdorferi is responsible
for Lyme disease.
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Microscopy
 Dark field-unstained
cells, hanging drop
 Phase contrast-good for
endospores or eucaryotic
cells
 Fluorescence-use
fluorochromes, orange or
green
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Staining: differential
 Gram’s stain
-divides bacteria into two
classes
-Gram positive-staph,
strep
-Gram negativehemophilus, 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)
Pseudomonas
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 Systemic or topical
 Bacteriocidal (kill)
-penicillins, cephalosporins
 Bacteriostatic (inhibit)
-tetracyclines,
erythromycin,
sulfonamides
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Mode of Action:
 Inhibition of cell wall
synthesis
 Destruction of cell
wall
 Inhibition of
bacterial protein
synthesis
 Inhibition of other
bacterial metabolism
Drug Resistance
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 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
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.
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Morphology
 four general shapes
helical – a spiral
polyhedral – many surfaces
binal - 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
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T4 bacteriophage (DNA virus).
Enveloped virus-Herpes simplex virus (HSV6, DNA virus)
on a peripheral blood lymphocyte
Herpes Simplex-envelope
Bacteriophagic-binal
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Adenovirus
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 Absorption and
penetration of cell
membrane
 Latency
 Replication
 Cytotoxicity
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 Chemotherapy
 Hinder intracellular
replication
 Acyclovir for Herpes
 Amantidine for Influenza
 Immunotherapy
 Acute infection
 Prophylaxis-vaccination
 Role of antibiotics
This innocent-looking
virus causes the oftendeadly Ebola
hemorrhagic fever.
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 Intracellular parasite
 Coccoid, gram-neg
bacteria
 Have both RNA & DNA
 Three species-C. trachomatis
-C. psittaci
-C. pneumoniae
Elementary body C. trachomatis
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 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
membrane-bound vacuole
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 Intracellular parasite
 Coccoid, gram-neg
bacteria
 Induces phagocytosis
to enter cells
 Three species-
Rickettsia rickettsii
in endothelial cells
of a blood vessel
from a patient with
fatal RMSF
-R. prowazekii
-R. Typhi
-R. rickettsii
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 Indirect fluoresent
antibody staining
 Special staining
required
Serological:
-Weil Felix reaction test
-Complement Fixation Test
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 Gram negative
 Spiral, slender, long
bacteria
 Very mobile-axial
filament
 Can be free living or
parasitic
 Three genus:
-Treponema
-Leptospira
-Borrellia
T. pallidum - human syphilus - ("For one
small pleasure I suffer a thousand
misfortunes")
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Diagnosis:
-clinical presentation
-geographical location
-serological tests
-VDRL, agglutination
-darkfield microscopy of
lesions & silver staining
-cultures
Note: axial filament
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Characteristics:
 Lack cell walls
 Vary in shape
 Smallest bacteria capable of
reproduction
 Extracellular parasite
Diagnosis:
-enzyme immunoassay
-cultures take 1-3 weeks
-x-Ray
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 Eucaryotic, spore bearing
 Plant like organisms-lack
chlorophyll
Disease(s):Blastomycosis
 Few are pathogenic
 Opportunistic
 Diseases in humansmycoses
 4 Divisions
Skin lesion following dissemination
from the lungs.
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Classification by Disease
Presentation
Cutaneous 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
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Diseases:
Dermatophytes-Skin
-Body ringworm
-Scalp ringworm
Candidiasis
-Thrush
-Vaginal Candida infections
Mycosis
-histoplasmosis
-blastomycosis
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 the2016-03-22
fungus Candida albicans.
Diagnosis:
 Clinical presentation-imp
 Laboratory Investigations
 microscopic
visualization
 Serological test-blood
culture
 Ensure good specimens
taken
 Lung biopsy
 Broncho speciments
 Urine by catheter
Disease(s):Histoplasmosis
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Organisms that live within upon or at the expense of
another, do not contribute to survival of host.
Classification:
 Protozoa
-unicellular
 Metazoa
-multicellular
Reproduction-by binary fission and sexual
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Classification:
Protoza-unicellular
Toxoplasma gondii in the
bronchoalveolar lavage material
-Amoeba
-Pneumocystis carinii
-Plasmodia
-Toxoplasma
-Giardia
Giardia2016-03-22
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)
-Schistosomiasisswimmer’s itch
-Clonorchissis-liver fluke
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.2016-03-22
Acarus scabei
-scabies
http://www.biosci.ohiostate.edu/~parasite/picture
s/scabies_mite.gif
Pediculi
-capitis
-corporis
-pubis
Fleas
-the human flea is an
endangered species
-rat flea-plague
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 Depends on patient-pathogen interaction
 Local effects
-due to inflammation
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".
-blood vessels dilate
-skin red, warm
-capillaries in area permeable-fluid in
-swelling
-chemicals released-pain
-neutrophiles, etc.
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 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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Fever
 Chills
-thermoregulatory set
point
-increased muscle
activity
 Sweats
-defervescence
(subsidence of fever
to normal)
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.
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Fever
 Differential Diagnosis
-infection
-Thyrotoxicosis
-Dehydration
-Trauma
-MI
-Malignancy
Treatment
-reason to treat fever
-antipyretics-ASA, Acetaminophen, etc.
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Fever
 Systemic Manifestations
 Leukocytosis
-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.
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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
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 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 Surveillance
 Active Surveillance
 Surveillance is information for action
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What does it consist of:
 Morbidity and mortality reports
 Reports of field investigation
 Isolation and ID of infectious agents by labs
 Data concerning the availability, use and effects of
immunizing agents and other control substances
 Immunity levels in segments of population
 Report with above data prepared and distributed
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Case Reports-provide minimal identifying data.
 Name, address, age, gender
 Address
 Diagnosis
 Date of report of each patient
 Dates of onset
 Basis 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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