The critical community size (CCS) is the minimum size of a closed population within which a human-to-human,
non-zoonotic pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...
can persist indefinitely.
[Bartlett MS The critical community size for measles in the United States. J R Stat Soc er A 1960;123:37–44.]
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.
[Daniel T. Haydon. Identifying Reservoirs of Infection: A Conceptual and Practical Challenge. Emerg Infect Dis. 2002 December; 8(12): 1468–1473.] This epidemiologic phenomenon was first identified during
measles
Measles is a highly contagious infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than , cough, ...
outbreak
In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire ...
s in the 1950s.
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
See also
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References
External links
The Collection of Biostatistics Research Archive'Epidemiology'– In: Philip S. Brachman, ''
Medical Microbiology
Medical microbiology, the large subset of microbiology that is applied to medicine, is a branch of medical science concerned with the prevention, diagnosis and treatment of infectious diseases. In addition, this field of science studies vario ...
'' (fourth edition), US
National Center for Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. Th ...
Monash Virtual Laboratory- Simulations of epidemic spread across a landscape
Infectious diseases
Epidemiology
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