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African swine fever endemic persistence in wild boar populations: key mechanisms explored through modelling
  • Vincenzo gervasi,
  • Vittorio Guberti
Vincenzo gervasi
Istituto Superiore per la Protezione e la Ricerca Ambientale
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Vittorio Guberti
Istituto Superiore per la Protezione e la Ricerca Ambientale
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Abstract

African swine fever (ASF), is a serious global concern from an ecological and economic point of view. While it is well established that its main transmission routes comprise contact between infected and susceptible animals and transmission through contaminated carcasses, the specific mechanism leading to its long-term persistence is still not clear. Among others, a proposed mechanism involves the potential role of convalescent individuals, which would be able to shed the virus after the end of the acute infection. Using a spatially explicit, stochastic, individual-based model, we tested: 1) if ASF can persist when transmission occurs only through infected wild boars and infected carcasses; 2) if the animals that survive ASF can play a relevant role in increasing ASF persistence chances; 3) how hunting pressure can affect the ASF probability to persist. The scenario in which only direct and carcass-mediated transmission were contemplated had 52% probability of virus persistence 10 years after the initial outbreak. The inclusion of survivor-mediated transmission corresponded to slightly higher persistence probabilities (57%). ASF prevalence during the endemic phase was generally low, ranging 0.1-0.2%. The proportion of seropositive individuals gradually decreased with time and ranged 4.5 – 6.6%. Our results indicate that direct and carcass-mediated infection routes are sufficient to explain and justify the long-term persistence of ASF at low wild boar density and the ongoing geographic expansion of the disease front in the European continent. During the initial years of an ASF outbreak, hunting should be carefully evaluated as a management tool, in terms of potential benefits and negative side-effects, and combined with an intensive effort for the detection and removal of wild boar carcasses. During the endemic phase, further increasing hunting effort should not be considered as an effective strategy. Additional effort should be dedicated to finding and removing as many wild boar carcasses as possible.

Peer review status:ACCEPTED

22 Apr 2021Submitted to Transboundary and Emerging Diseases
04 May 2021Submission Checks Completed
04 May 2021Assigned to Editor
08 May 2021Reviewer(s) Assigned
06 Jun 2021Review(s) Completed, Editorial Evaluation Pending
06 Jun 2021Editorial Decision: Revise Minor
17 Jun 20211st Revision Received
17 Jun 2021Submission Checks Completed
17 Jun 2021Assigned to Editor
18 Jun 2021Review(s) Completed, Editorial Evaluation Pending
18 Jun 2021Editorial Decision: Accept