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High Virulence
Ability of agent to cause disease in normally resistant individual
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Low virulence
Agent is only effective in host w/ low resistance
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Pathogenicity
- 1- Ability to produce infection & propagate in host- overcomes host defenses
- 2- Agents ability to generate products that cause tissue damage
- 3- Host cellular responses to infectious agents- also leads to tissue damage (hyersensitivity reactions)
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Virus
- Smallest pathogen
- Has DNA or RNA in protein shell- capsid
- Not capable of independent metabolsm
- Requiring living cellsin which to replicate- may or may not interfere w/ cell functions
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Virus Cycle
- Attach to cell
- Penetrate it
- Un-coat
- Replicate
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Viremia
Presence of viruses in the blood
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Influenza
- Viral respiratory diease
- Fever, headache, myalgia,
- Complications: bronchitis and bacterial pneumonia
- Influenza Virus A
- Influenza Virus B
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Measles
- Rubeola
- Highly contagious
- RNA measles virus
- Incubation period: 10-21 days
- Fever, cough, conjunctivitis, malaise
- Rash
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Rubella
- Viral RNA disease
- Children 5-15
- Mildly contageous
- Lymphadenopathy, rash 3-5 days, conjuctivitis
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Mumps
- Acute generalized infection, RNA virus
- Fever, malaise, parotitis
- Complications: meningitis, pancreatitis, orchitis
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