R Flashcards
What is infectious disease?
Disease caused by a microorganism
Potentially transferrable to others
What is a communicable disease?
An infectious disease that can be transmitted from one individual to another
What is a contagious disease?
A very communicable disease, capable of readily spreading between individuals
What is a transmissible disease?
A disease that is transmitted between individuals by ‘unnatural’ routes
What is herd immunity?
Indirect protection from an infectious disease when a large percent of the population are immune
What is R?
Effective reproductive number at any point of an epidemic
The number of cases that directly arise from an infectious individual that enters a susceptible population
What is R0?
The basic reproductive number at a start of an epidemic
The number of new cases that arise directly from an infectious individual that enters a susceptible population
What is the equation for R0?
R0 = how long person is infectious for X number of people infected per time period X probability of transmission if contact occurs
What is the equation for R?
R0 X S
S = proportion of population susceptible to the infection
What happens if R0 is less than, more than or equal to 1?
<1 = extinction of pathogen 1 = endemic of disease >1 = epidemic of disease
What is an epidemic?
Outbreak - attacks many individuals and spreads
What is an endemic?
A disease existing permanently in a population
What happens to the amount of susceptible population as a disease spreads?
As new cases increase, susceptible population decreases
What is defined as ‘contact’?
Depends on the disease - however it is spread
What happens to the value of R as the number of cases increases?
R decreases as cases increase
