Evaluating the Influence of Epidemiological Parameters and Host Ecology on the Spread of Phocine Distemper Virus through Populations of Harbour Seals
Authored by John Harwood, Justin MJ Travis, Catriona M Harris
Date Published: 2008
DOI: 10.1371/journal.pone.0002710
Sponsors:
United Kingdom Natural Environment Research Council (NERC)
Platforms:
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Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
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Abstract
Background: Outbreaks of phocine distemper virus (PDV) in Europe during
1988 and 2002 were responsible for the death of around 23,000 and 30,000
harbour seals, respectively. These epidemics, particularly the one in
2002, provided an unusual opportunity to estimate epidemic parameters
for a wildlife disease. There were marked regional differences in the
values of some parameters both within and between epidemics.
Methodology and Principal Findings: We used an individual-based model of
seal movement that allowed us to incorporate realistic representations
of space, time and animal behaviour into a traditional epidemiological
modelling framework. We explored the potential influence of a range of
ecological (foraging trip duration, time of epidemic onset, population
size) and epidemiological (length of infectious period, contact rate
between infectious and susceptible individuals, case mortality)
parameters on four readily-measurable epidemic characteristics (number
of dead individuals, duration of epidemic, peak mortality date and
prevalence) and on the probability that an epidemic would occur in a
particular region. We analysed the outputs as if they were the results
of a series of virtual experiments, using Generalised Linear Modelling.
All six variables had a significant effect on the probability that an
epidemic would be recognised as an unusual mortality event by human
observers.
Conclusions: Regional and temporal variation in contact rate was the
most likely cause of the observed differences between the two epidemics.
This variation could be a consequence of differences in the way
individuals divide their time between land and sea at different times of
the year.
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