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Introducing the outbreak threshold in epidemiology.

ABSTRACT: When a pathogen is rare in a host population, there is a chance that it will die out because of stochastic effects instead of causing a major epidemic. Yet no criteria exist to determine when the pathogen increases to a risky level, from which it has a large chance of dying out, to when a major outbreak is almost certain. We introduce such an outbreak threshold (T?), and find that for large and homogeneous host populations, in which the pathogen has a reproductive ratio R?, on the order of 1/Log(R?) infected individuals are needed to prevent stochastic fade-out during the early stages of an epidemic. We also show how this threshold scales with higher heterogeneity and R0 in the host population. These results have implications for controlling emerging and re-emerging pathogens.

SUBMITTER: Hartfield M

PROVIDER: S-EPMC3680036 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Introducing the outbreak threshold in epidemiology.

Hartfield Matthew M Alizon Samuel S

PLoS pathogens 20130606 6

When a pathogen is rare in a host population, there is a chance that it will die out because of stochastic effects instead of causing a major epidemic. Yet no criteria exist to determine when the pathogen increases to a risky level, from which it has a large chance of dying out, to when a major outbreak is almost certain. We introduce such an outbreak threshold (T₀), and find that for large and homogeneous host populations, in which the pathogen has a reproductive ratio R₀, on the order of 1/Log ...[more]

PMID: 23785276

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