Chapter 16: Host-Microbe Interactions: Duration + Distribution of pathogens Flashcards
What are the 3 durations of symptoms?
- acute
- chronic
- latent
What is an acute symptom? (2)
- Rapidly developing
- short duration
ex. influenza
What is a chronic symptom? (2)
- slow to develop
- continual duration
ex. tuberculosis
What is a latent symptom? (2)
- inactive for a period of time
- can be reactivated
- ex. cold sores - herpes virus
Why is the number of microbes important?
- if too few microbes enter, immune system will fight them off and prevent disease
How will the likelihood of disease increase?
microbe number increases
How can virulence and pathogenicity of a microbe be expressed numerically? (2)
- infectious dose
- Potency of a toxin
Infectious dose: what does ID50 mean?
- causes infection in 50% of the population
ex. Bacillus anthracis
How many endospores does ID50 equate to, by:
- ingestion
- inhalation
- through a cute in the skin
ingestion: 250 000 to 1 mil
inhalation: 10 000 to 20 000
Through a cut in the skin: 10-20
How is potency of a toxin expressed by? (2)
- lethal dose
- LD50 kills 50% of the infected population
What is a localized infection?
- confined to small area of the body
What is a systemic infection?
- microbes or toxins are spread throughout the body
ex. covid
What is septicimia?
- systemic infection of the blood
What are 3 types of septicimia?
bacteremia - bacteria in the blood
toxemia - toxins in the blood
viremia - viruses in the blood
What is sepsis?
- life threatening systemic inflammatory response, usually due to bacteremia
