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:[citation needed]
This virus-related article is a stub.