Critical community size explained

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:

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

External links

• The Collection of Biostatistics Research Archive
• 'Epidemiology' – In: Philip S. Brachman, Medical Microbiology (fourth edition), US National Center for Biotechnology Information
• Monash Virtual Laboratory - Simulations of epidemic spread across a landscape
• People's Epidemiology Library

Notes and References

1. Bartlett . M. S. . The critical community size for measles in the United States . Journal of the Royal Statistical Society. Series A (General). 1960 . 123 . 1 . 37–44 . 10.2307/2343186. 2343186 .
2. Haydon . Daniel T . Cleaveland . Sarah . Taylor . Louise H . Laurenson . M Karen . Identifying reservoirs of infection: a conceptual and practical challenge . Emerging Infectious Diseases. 2002 . 8 . 12 . 1468–1473 . 10.3201/eid0812.010317. 12498665 . 2738515 .