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Define Pathogen
anything that causes infection
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Define Incidence
number of new cases of an infectious disease in a given population
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Define Prevalence
number of active cases of an infectious disease in a given population
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Define Endemic
stable incidence and prevalence of an infectious disease in a given population
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Defeine Epidemic
sudden increase in incidence of an infectious disease in a given population
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Define Pandemic
spread of an infectious disease beyond continental border
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Define Colonization
normal, harmless residence of local microorganism on mucous and cutaneous membranes
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Define Resident Flora
live in or on the host and recolonize quickly if disturbed; symbiotic relationship with the host
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Define Transient Flora
reside temporarily in or on the host
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Define Opportunistic
infections from resident flora gone wild when the host's immune system is compromised
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Types of Infection
- Opportunistic Infections
- Virulent Infections
- Nosocomial Infections
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What are Opportunistic Infections?
host's immune system is compromised; resident flora overgrow or move into a new location in the body
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What are Virulent Infections?
microorganism that is consistently capable of causing disease
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What is a Nosocomial Infection?
an infection from a hospital or clinical situation. They may be opportunistic or virulent in nature.
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What are the types of Microorganisms?
- Bacteria
- Viruses
- Fungi
- Parasites
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How are Bacteria classified?
- by motility
- Gliding
- Spirochetes
- Mycoplasmas
- Rigid
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What are the classifications of rigid bacteria?
- Actinomycetes
- Unicellular forms
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What are the classifications of unicellular rigid bacteria?
- Intracellular obligate parasites
- Free living bacteria
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What are the classifications of free-living bacteria?
- Cocci --> round and immobile
- Bacilli --> rod shaped and may be mobile
- Spiral --> corkscrews
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How are free-living bacteria classified?
- classified by their response to gram staining
- Gram Positive --> retain dye, dark purple
- Gram Negative --> resist stain, pink
- Acid Fast --> resist decoloration, red
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What happens if bacteria get past the initial membrane defense and multiply and creat a colony in the host?
- Acute inflammatory response
- Phagocytic cells recruited
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What happens if bacteria get past the 1st response?
bacteria will use the interstitial fluid, blood, and lymph networks to spread through the body
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What happens if bacteria gets to the lymph nodes?
- Another attempt to clean them out
- If these fail then clumps of bacteria begin to flood the bloodstream
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What are antibiotic?
cultural mechanism for discouraging microorganisms.
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What are Viruses?
- genetic parasites composed of DNA or RNA and a capsule
- dependent on host cell for energy and for replication
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What are the 2 mechanisms for invasion of the host cell?
- Adherence and endocytosis
- Adherence and injection of genetic material
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What are the two ways for a virus to be released from a cell?
- release by budding from the host cell , host cell is not destroyed --> birth
- release by lysing the host cell, the host cell is destroyed -->scene from "Alien"
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What are the ways of classifying viruses?
- Size
- DNA or RNA
- mode of replication
- capsule structure
- type of host cell
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How do DNA viruses replicate?
- produce mRNA in the host cell nucleus and with the host cell's enzymes
- host cell's machinery is used to translate the viral mRNA's
- (herpes simplex)
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What are the two ways that RNA viruses replicate?
- Straight-replicating
- -->Positive Copy
- -->Negavie Copy
reverse transcriptase
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How does reverse transcriptase work?
- converts the viral RNA chromosome into viral DNA
- viral DNA is incorporated into the host cell's chromosome
- Viral proteins are produced from viral mRNA using the host machinery
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How does positive copy RNA work?
Postive copy RNA is used as a direct template to make viral proteins and complementary negative RNA
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How does negative copy work?
converted into a complementary positive RNA which is used to produce viral proteins or progeny chromosome
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What are the treatments for viral infections?
- self-limited
- anti virals
- natural
- immunizations
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What are Fungi?
- yeasts and molds
- nonphotosynthetic, eukaryotic protists that exist everywhere
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What is good at cleaning up fungi?
Phagocytes especially neutrophils and some monocytes and eosinophils
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What are the types of mycoses?
- Opportunistic mycoses
- Superficial mycoses
- Subcutaneous mycoses
- Systemic mycoses
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What is an opportunisitc mycoses?
normal flora that become bothersome
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What are superficial mycoses?
occur only on dead, keratinized tissue
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What are subcutaneous mycoses?
occur in subcutaneous tissue due to trama
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What are systemic mycoses?
usually caused by soil fungi that are inhaled
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What are the four types of parasites?
- Protozoa
- Nematohelminthes (round worms)
- Platyhelminths (flatworms, tapeworms)
- Arthropoda
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What is the chain of transmission?
Reservoir --> Portal of Exit --> Mode of Transmission --> Portal of Entry --> Susceptible Victim
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What are things that help the pathogen enter the host?
- Chemicals that promote adherence --> glycocalyx
- Mechanical structures that promote adherence --> pili and fimbriae
- Ability to attach to host proteins
- Ablitlity to attach to rough surfaces
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What are things that help the pathogen get past the host's defenses?
- Bacterial enzymes that dissolve host blood or connective tissue proteins
- Encapsulation with a polysaccaride prevents fixation of complement and opsonization
- Survival inside phyocytes
- Endospore formation
- Production of IgA protease
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What are the characteristics that harm or kill host cells?
- bacterial toxins kill host cells and induce inflammation
- -->Exotoxins
- -->Endotoxins
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What are the host characteristics that affect infection?
- Epithelial barriers
- Nutritional status
- Chronic Illness
- Age
- Immune Status
- Poor Sanitation
- Crowded living conditions
- Improper handling of food
- Climate/Seasonal patterns
- Geographic location
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What are the stages of infection?
- Colonization
- Invasion
- Multiplication
- Spread
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What are the portals of entry for a pathogen?
- Penetration
- Direct Contact
- Ingestion
- Inhalation
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What are the stages in a disease course?
- Incubation stage
- Prodromal Stage
- Acute Stage
- Convalescent Stage
- Resolution Stage
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What are the 3 lines of defense?
- Physical Barriers
- Inflammatory Response
- Immune Response
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What are the physical barriers?
- skin
- mucous membranes of GI, GU, and respiratory tracts by action of pH and or resident flora
- mucociliary blanket of respiratory passages
- flushing of tears, urine, bowel evacuation
- various substances in bodily secretions such as lysosomes in tears
- ongoing phagocytosis
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What is the inflammatory response?
- Mast cell degranulation --> blood vessel inflammatory responses; phagocytic action of granulocytes
- fever -->heightened phagocytosis
- Plasma protein systems, Complement cascade, coagulation cascade, Kinin System
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What is the immune response?
- Immunoglobulins, and T cytoxic lymphocytes
- Lymphocyte production of cytokines
- Protection through humoral and cell-mediated immune response and the production of antibodies and memory cells.
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