Critical community size

The critical community size (CCS) is the minimum size of a closed population within which a human-to-human, non-zoonotic pathogen can persist indefinitely.^[1]

When the size of the closed population falls below the critical community size level, the low density of infected hosts causes extinction of the pathogen.^[2] This epidemiologic phenomenon was first identified during measles outbreaks in the 1950s.^[1]

The critical community size depends on:^[3]

• Speed of transmission
• How long until a person who has recovered remains immune
• Fatality rate
• Birth and death rate in the general population

See also

• Compartmental models in epidemiology – Type of mathematical model used for infectious diseasesPages displaying short descriptions of redirect targets
• Epidemiology – Study of health and disease within a population
• Force of infection – Rate at which susceptible individuals acquire an infectious disease
• Mathematical modelling of infectious disease – Using mathematical models to understand infectious disease transmissionPages displaying short descriptions of redirect targets
• Transmission risks and rates