Abstract:
A stochastic model designed to simulate transmission dynamics of African swine fever virus
(ASFV) in a free-ranging pig population under various intervention scenarios is presented.
The model was used to assess the relative impact of the timing of the implementation of different
control strategies on disease-related mortality. The implementation of biosecurity
measures was simulated through incorporation of a decay function on the transmission
rate. The model predicts that biosecurity measures implemented within 14 days of the onset
of an epidemic can avert up to 74% of pig deaths due to ASF while hypothetical vaccines
that confer 70% immunity when deployed prior to day 14 of the epidemic could avert 65% of
pig deaths. When the two control measures are combined, the model predicts that 91% of
the pigs that would have otherwise succumbed to the disease if no intervention was implemented
would be saved. However, if the combined interventions are delayed (defined as
implementation from > 60 days) only 30% of ASF-related deaths would be averted. In the
absence of vaccines against ASF, we recommend early implementation of enhanced biosecurity
measures. Active surveillance and use of pen-side diagnostic assays, preferably
linked to rapid dissemination of this data to veterinary authorities through mobile phone
technology platforms are essential for rapid detection and confirmation of ASF outbreaks.
This prediction, although it may seem intuitive, rationally confirms the importance of early
intervention in managing ASF epidemics. The modelling approach is particularly valuable in
that it determines an optimal timing for implementation of interventions in controlling ASF
outbreaks.
