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An infectious disease is said to be endemic when it can be sustained in a population without the need for external inputs. This means that, on average, each infected person is infecting exactly one other person (any more and the number of people infected will grow sub-exponentially and there will be an epidemic , any less and the disease will ...
In epidemiology, force of infection (denoted ) is the rate at which susceptible individuals acquire an infectious disease. [1] Because it takes account of susceptibility it can be used to compare the rate of transmission between different groups of the population for the same infectious disease, or even between different infectious diseases.
is the average number of people infected from one other person. For example, Ebola has an of two, so on average, a person who has Ebola will pass it on to two other people.. In epidemiology, the basic reproduction number, or basic reproductive number (sometimes called basic reproduction ratio or basic reproductive rate), denoted (pronounced R nought or R zero), [1] of an infection is the ...
For the full specification of the model, the arrows should be labeled with the transition rates between compartments. Between S and I, the transition rate is assumed to be (/) / = /, where is the total population, is the average number of contacts per person per time, multiplied by the probability of disease transmission in a contact between a susceptible and an infectious subject, and / is ...
Kermack–McKendrick theory is a hypothesis that predicts the number and distribution of cases of an infectious disease as it is transmitted through a population over time. Building on the research of Ronald Ross and Hilda Hudson , A. G. McKendrick and W. O. Kermack published their theory in a set of three articles from 1927, 1932, and 1933.
Mass vaccination to induce herd immunity has since become common and proved successful in preventing the spread of many contagious diseases. [22] Opposition to vaccination has posed a challenge to herd immunity, allowing preventable diseases to persist in or return to populations with inadequate vaccination rates. [45] [46] [47]
Generally, in infectious disease statistics, the onset of clinical symptoms for all the hosts are reported. For two successive generations (or cases or hosts) in a chain of infection, the serial interval is defined as the period of time between the onset of clinical symptoms in the first host (infector) and the onset of analogous clinical ...
In epidemiology, particularly in the discussion of infectious disease dynamics (mathematical modeling of disease spread), the infectious period is the time interval during which a host (individual or patient) is infectious, i.e. capable of directly or indirectly transmitting pathogenic infectious agents or pathogens to another susceptible host ...