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 (, "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 Germ theory of d ...
can persist indefinitely.
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.
This epidemiologic phenomenon was first identified during
measles
Measles (probably from Middle Dutch or Middle High German ''masel(e)'', meaning "blemish, blood blister") is a highly contagious, Vaccine-preventable diseases, vaccine-preventable infectious disease caused by Measles morbillivirus, measles v ...
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'' (fourth edition), US
National Center for Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the 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. The NCBI is lo ...
Monash Virtual Laboratory- Simulations of epidemic spread across a landscape
Infectious diseases
Epidemiology
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