lecture 35 - cellular basis of infectious disease Flashcards
What are the 5 stages of infectious disease?
Incubation period, prodromal period, illness, decline, convalescence
What occurs in the ‘incubation period’ stage of an infectious disease?
Pathogen begins to inhabit host, but there are no signs or symptoms
What occurs in the ‘prodromal period’ stage of an infectious disease?
Vague, general symptoms
What occurs in the ‘illness’ stage of an infectious disease?
Most severe signs/symptoms - maximum number of microorganisms in the host.
What occurs in the ‘decline’ stage of an infectious disease?
Declining signs/symptoms and decline number of microorganisms infecting
What occurs in the ‘convalescence’ stage of an infectious disease?
No signs/symptoms, very few microorganisms remain
What virus causes the common cold?
Rhinovirus
What are the structural characteristics of a rhinovirus?
ssRNA, no envelope
What are the 6 components of the the chain of infection?
Causative agent, reservoir/source, means of exit, mode of transmission, portal of entry, person at risk.
What are examples of causative agents in terms of the chain of infection?
Viruses, bacteria, parasites
What are examples of reservoirs/sources in terms of the chain of infection?
Humans, animals, fomites, food, water
What are examples of means of exit in terms of the chain of infection?
Excretions, secretions, droplets
What are examples of modes of transmission in terms of the chain of infection?
Contact, airborne, vectors
What are examples of portals of entry in terms of the chain of infection?
Respiratory, gastrointestinal tracts, genitourinary tracts, mucous, skin
What are examples of people at risk in terms of the chain of infection?
Young, elderly, immunocompromised.
How can the chain of infection be broken at the causative agent stage?
Rapid detection and treatment
How can the chain of infection be broken at the reservoir/source stage?
Good hygiene, sterilisation, disinfection
How can the chain of infection be broken at the means of exit stage?
Waste removal, disinfection
How can the chain of infection be broken at the mode of transmission stage?
Airflow control, bed spacing
How can the chain of infection be broken at the portal of entry stage?
Aseptic technique
Define mortality, in terms of an infectious disease
Incidence of death in a population
Define morbidity
Incidence of disease, including fatal and non-fatal cases
Define incidence
The number of new cases of a disease in a given time period
Define prevalence, in terms of epidemiology
Total number of new and existing cases of a disease in a population at a give time
Define endemic, in terms of disease
Amount of disease usually present in a community - ‘baseline’
Define sporadic, in terms of disease
A disease that occurs infrequently and irregularly
Define epidemic
A sudden increase in cases of a disease across a broad geographical area.
Define pandemic
An epidemic that spans several countries or continents
