EXAM 3 CHAPTER 15 Flashcards
Distinguish between signs and symptoms of disease
Signs are objective and measurable where as symptoms are subjective (pain)
Explain the difference between communicable and a noncommunicable disease
Communicable can be spread from person to person through direct or indirect contact. Noncommunicable cannot be spread person to person
Define iatrogenic disease
Contracted as a result of a medical procedure
Define nosocomial disease
Acquired in hospital settings
Define zoonotic disease
Diseases transmitted from animals to humans
Define the incubation period
The start of an infection (no symptoms)
Define the prodromal period
The time of growth of the infection
Define the period of illness
When the levels of infection are high enough for signs and symptoms to show
Define the period of decline
Infection levels decrease and signs/symptoms subside
Define the period of convalescence
When the infection goes away entirely (full decline)
What are Koch’s four postulates
- Causative agent must be found only in diseased animals
- Isolate the causative agent and grow in pure culture
- Cultured agent must cause the same disease after innoculating a healthy organism
- Causative agent must be reisolated
What are Koch’s postulates used for?
Used to determine whether a particular microorganism is a pathogen.
What are molecular Koch’s postulates?
- The phenotype of disease should be associated with pathogenic strains
- Inactivation of the gene suspected to contribute to pathogenicity should result in measurable loss pathogenicity
- Reversion of the inactive gene should restore disease phenotype
What is the median infectious dose?
The number of pathogen cells or virions required to cause active infection in 50% of innoculated animals
What is the median lethal dose?
The number of pathogenic cells, virions or amount of toxin required to kill 50% of infected animals.
