-15- Micro Ch. 15

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Prevalence: ___________ of a disease is the percent of the population having a particular disease at any given time. Both new and already existing cases
sporadic: A few isolated cases in widespread areas

Poses no great threat to the overall pop.
Endemic: Disease is constantly present in a population or geographic area.
Epidemic: Many people acquire the disease in a short period of time.
Pandemic: Worldwide epidemic
Outbreak: any statistical abnormality
acute disease: What is the severity or duration of a disease that develops rapidly but last only a short time? eg. flu
chronic: What is the severity or duration of a disease that develops more slowly, body reactions less severe but are continuous or recurrant for long periods of time. eg. syphilis, herpes, leprosy.
Subacute disease: What is the severity or duration of a disease that is intermediate btwn acut and chronic?
Latent disease: What is the severity or duration of a disease that is the causative agent remains inactive but can become active producing disease?
Herd immunity: What is the severity or duration of a disease that many individuals within a population are immune? Ones that prevent rapid spread of the disease.
Local infection: Infection in which an organism limited to relative small area
Systemic infection: Organism and or products are spread throughout the body.
Focal infection: Local infection that spreads to another specific part of the body.
Bacteremia: Presence of bacteria in the blood.
sepsis: the presence of a toxin or pathogenic organism in the blood.
Toxemia`: Presence of toxins in the blood.
Viremia: viruses in the blood.
Primary infection: Acute infection caused by the initial infective agent.
Secondary Infection: Usually caused by an opportunist after primary infection has weakened the host.
Subclinical or Asymptomatic infection: No apparent signs or symptoms of disease.
Period of incubation: Interval btwn infection and onset symptoms. Varies according to:
host resistance
# of organisms
degree of virulence
rate of growth (generation time)

During this stage there are no symptoms or signs.
Prodromal period: 1st symptoms of disease appear. Usually gen. symptoms:
nausea
fever
headache
malaise
Period of Acme or Illness: acute stage of disease

more specific signs of disease appear.
Period of decline: Signs and symptoms subside. Often preceded by a crisis period, followed by recovery.
Period of convelescence: Individual regains strength; body's systems return to normal
false: T/F
In the pattern of infection, at the period of incubation and the period of convelescence, the individual is not contagious.
1. Find a suitable and susceptible host and multiply within. 2. have a portal of entry. 3. Enter in sufficient numbers 4. Be able to attach to host tissues (adherance) 5. Must damage the host cells.: What are the 5 MUSTs to making a pathogen a pathogen?

OR

What must an organism do to cause an infectious disease?
Find a suitable and susceptible host and multiply within: Predisposing factors:
stress
fatigue
nutrition
age
antibiotic therapy
babies
gerontology
Have a portal of entry: Mucous membranes: Respiratory tract, genitourinary, and conjunctiva.
Skin
Parenteral route: directly into deep tissues
Transplacental (STORCH)
Enter in sufficient numbers: (LD50) (ID50)
It could take only 1 to billions to make you sick or die.
Be able to attach to host tissues (adherence): Adhesions or ligands located on capsules or fimbrae/pili.
Neisseria gonorrhoeae uses pili to attach to epithelial cells of the urethra. Strep. mutans forms dextran to attach to tooth enamel.
by invasiveness and evasiveness: How do pathogens penetrate host defenses?
a. bacterial structures b. enzymes and antichemotactic factors c. Antigenic Variation d. Invasins: How do pathogens penetrate the host's defenses? (4)
capsule M protein opa waxes: What are the bacterial structures that contribute to evasiveness and invasiveness?
capsule: inhibits phagocytosis (and complement)
helps to adhere to things
Some cell components also resist phagocytosis
eg. M protein
opa: causes cell to take in the pathogen (attach to host walls)
waxes: Cell wall component that prevents digestion by phagocytes
M protein: found on both cell surface and fimbrae

mediates attachment of the bacterium to epithelial cells of the host and helps the bacterium resist phagocytosis by WBCs.

Increases the virulence of the microorganism.
enzymes and antichemotactic factors: anything with the word -ase on it

chemical repellant
Antigenic Variation: change surface molecules
Invasins: surface protein that rearranges actin filaments of the cytoskeleton leading to movement of the pathogen into the host cell.
Virulence: Degree of pathogenicity

(how bad of a bug is it)
1.Interferes with host cell metabolism (uses host cell nutrients) 2. Siderophores 3. Toxigenicity 4. Organisms may produce various invasive or toxic enzymes. 5. Mechanical damage 6. Blockage of vessels 7. Cytopathic effects: What are the mechanisms of virulence/damage to the host cells?

(7)
Siderophores: Bind host cells iron -> attaches to receptors on the bacterial surface -> takin into the bacterium
Toxingenicity: Ability of a microorganism to produce toxins.
Exotoxins Endotoxins Endotoxic/septic shock: What are the 3 types of toxingenicity?
Exotoxins: Released from the organism into the surrounding environment.
mostly proteins
Mostly gram positive bacteria.
Organism themselves need NOT be present for disease to occur.
A-B toxins
Membrane-disrupting toxins: Leukocidins
Hemolysin
Streptolysins
Leukocidins: Kills WBCs
Hemolysin: Lyses (breaks down) RBCs
Superantigens: causes excessive secretion of cytokines by T cells

Various signs and symptoms: fever, nausea, vomiting, diarrhea, and sometimes fatal shock.
Endotoxins: Part of the cell wall of Gram negative bacteria.
Lipopolysaccharide (lipid A)
Toxic to humans
Released after death of the organism.
Endotoxic/Septic shock: Phagocytes release tumor necrosis factor (TNF) -> damage to capillaries -> drop in BP -> shock.
Coagulase Kinases Hyaluronidase Collagenase IgA protease: What are the 5 invasive or toxic enzymes?
Coagulase: Clots blood.
Organisms are "walled off" from host defenses.
Kinases: Streptokinase & Staphlokinase

Dissolves clots formed by the host to isolate the infection.
Hyaluronidase: enzyme
Dissolves substances that hold certain cells together.
(cell cement = Hyalurondic acid)
Collagenase: Breaks down collagen
connective tissue
IgA protease: Destroys IgA antibodies.
Mechanical Damage: Irritation and Inflammation
Autoimmune disease
Autoimmune Disease: Antibodies formed against an organism cross react with host cell tissue.
Blockage of vessels: Thrombosis (blood clot)
Embolism (blood clot that breaks free) or blockage of airways.
Cytopathic Effects: virus infections
Inclusion bodies
"balloon cells"
"giant cells"
Transformation
Cell lysis/Bursting of cells -> which leads to release of more virons.
Inclusion bodies: granules in the cytoplasm of infected cells.
"balloon cells": due to fluid accumulation
"giant cells": fusion of cell membranes
syncytium
Transformation: Conversion of normal cells to malignant cells
Spread of infection: ________ __ __________ has to be transmitted (find a new host or resevior) or die.

We are talking about communicable disease.
Portal of exit: Respiratory tract: coughing sneezing, talking, saliva
GI tract: feces and saliva
Genital tract secretions: STDs
Urinary tract: urine
Skin and wounds: Direct contact or fomites (inantomite objects)
Biting insects (Anthropod vectors)
Contaminated needles
Breast milk
1. Respiratory tract: coughing sneezing, talking, saliva 2. GI tract: feces and saliva 3. Genital tract secretions: STDs 4. Urinary tract: urine 5. Skin and wounds: Direct contact or fomites (inantomite objects) 6. Biting insects: What are the 8 portal of exit?
resistance reproduce in a vector reservoirs: What are the mechanisms to increase survival of microorganisms?
resistance: Spores and Cysts, Dehydration resistant substances.

Shed in large #'s

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