Impact of population behavioural responses on the critical community size of infectious diseases

The critical community size (CCS) is the minimum closed population size in which a pathogen can persist indefinitely. Below this threshold, stochasticity eventually causes pathogen extinction. Here, we introduce a mechanism of behaviour-mediated persistence, by which the population response to the p...

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Bibliographic Details
Published inTheoretical ecology Vol. 17; no. 3; pp. 269 - 280
Main Authors Fair, Kathyrn R., Karatayev, Vadim A., Anand, Madhur, Bauch, Chris T.
Format Journal Article
LanguageEnglish
Published Dordrecht Springer Netherlands 01.09.2024
Springer Nature B.V
Subjects
Biomedical and Life Sciences
Coronaviruses
Disease transmission
Extinction
Feedback
Infectious diseases
Life Sciences
Parameters
Pathogens
Plant Sciences
Population number
Public health
Severe acute respiratory syndrome coronavirus 2
Social behavior
Species extinction
Stochasticity
Theoretical Ecology/Statistics
Viral diseases
Zoology
COVID-19
Social-ecological systems
Disease dynamics
Epidemic modelling
Critical community size
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Summary:The critical community size (CCS) is the minimum closed population size in which a pathogen can persist indefinitely. Below this threshold, stochasticity eventually causes pathogen extinction. Here, we introduce a mechanism of behaviour-mediated persistence, by which the population response to the pathogen alters the CCS. We exemplify this with infection transmission and non-pharmaceutical interventions (NPIs) in a population where both individuals and government authorities restrict transmission more strongly when case numbers are higher. This results in a coupled social-ecological feedback between disease dynamics and population behaviour. In a parameter regime corresponding to a moderate population response, this feedback allows the pathogen to avoid extinction in epidemic troughs. The result is a very low CCS that allows long-term pathogen persistence. Hence, an incomplete population response represents a “sour spot” that not only ensures relatively high case incidence but also promotes long-term persistence of the pathogen by reducing the CCS. We illustrate this mechanism for parameters corresponding to severe coronavirus 2 (SARS-CoV-2). Given the worldwide prevalence of small, isolated populations, these results emphasize the need for incorporating behavioural feedback into CCS estimates. Regional elimination and global eradication programs for vaccine-preventable infections could also account for this effect.
ISSN:1874-1738
1874-1746
DOI:10.1007/s12080-024-00589-1