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Proc Biol Sci. 2014 Jul 7;281(1786). pii: 20132962. doi: 10.1098/rspb.2013.2962.

The effect of seasonal birth pulses on pathogen persistence in wild mammal populations.

Author information

1
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK Environmental Futures Research Institute, Griffith University, Brisbane, 4111, Australia alisonpeel@gmail.com.
2
Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA Department of Biology, University of Florida, Gainesville, FL 32611, USA Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
3
Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
4
Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA.
5
US Geological Survey (retired), PO Box 65, Glen Haven, CO 80532, USA.
6
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK.
7
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.

Abstract

The notion of a critical community size (CCS), or population size that is likely to result in long-term persistence of a communicable disease, has been developed based on the empirical observations of acute immunizing infections in human populations, and extended for use in wildlife populations. Seasonal birth pulses are frequently observed in wildlife and are expected to impact infection dynamics, yet their effect on pathogen persistence and CCS have not been considered. To investigate this issue theoretically, we use stochastic epidemiological models to ask how host life-history traits and infection parameters interact to determine pathogen persistence within a closed population. We fit seasonal birth pulse models to data from diverse mammalian species in order to identify realistic parameter ranges. When varying the synchrony of the birth pulse with all other parameters being constant, our model predicted that the CCS can vary by more than two orders of magnitude. Tighter birth pulses tended to drive pathogen extinction by creating large amplitude oscillations in prevalence, especially with high demographic turnover and short infectious periods. Parameters affecting the relative timing of the epidemic and birth pulse peaks determined the intensity and direction of the effect of pre-existing immunity in the population on the pathogen's ability to persist beyond the initial epidemic following its introduction.

KEYWORDS:

birth pulse; critical community size; seasonality; stochastic model; wildlife epidemiology

PMID:
24827436
PMCID:
PMC4046395
DOI:
10.1098/rspb.2013.2962
[Indexed for MEDLINE]
Free PMC Article

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