Epidemiological analyses of African swine fever in the European Union (November 2017 until November 2018)

Abstract

This update on the African swine fever (ASF) outbreaks in the EU demonstrated that out of all tested wild boar found dead, the proportion of positive samples peaked in winter and summer. For domestic pigs only, a summer peak was evident. Despite the existence of several plausible factors that could result in the observed seasonality, there is no evidence to prove causality. Wild boar density was the most influential risk factor for the occurrence of ASF in wild boar. In the vast majority of introductions in domestic pig holdings, direct contact with infected domestic pigs or wild boar was excluded as the route of introduction. The implementation of emergency measures in the wild boar management zones following a focal ASF introduction was evaluated. As a sole control strategy, intensive hunting around the buffer area might not always be sufficient to eradicate ASF. However, the probability of eradication success is increased after adding quick and safe carcass removal. A wider buffer area leads to a higher success probability; however it implies a larger intensive hunting area and the need for more animals to be hunted. If carcass removal and intensive hunting are effectively implemented, fencing is more useful for delineating zones, rather than adding substantially to control efficacy. However, segments of fencing will be particularly useful in those areas where carcass removal or intensive hunting is difficult to implement. It was not possible to demonstrate an effect of natural barriers on ASF spread. Human‐mediated translocation may override any effect of natural barriers. Recommendations for ASF control in four different epidemiological scenarios are presented.

Epidemiological analyses of African swine fever in the European Union (November 2018 to October 2019)

“…Term of Reference 3 (TOR3) requested a review of the control measures applied by affected MSs to control the spread of ASF in wild boar and to eradicate infection. In the previous reporting period (EFSA, ), this assessment was based on a spatiotemporally explicit individual‐based model approach in structured geographic landscapes. No contradicting evidence has subsequently emerged and, therefore, the earlier conclusions and recommendations are still valid.…”

“…In the previous report (EFSA, ), an extensive literature review had been undertaken to study the efficacy of different methods to control ASF spread through reducing wild boar population densities. The review was updated in this reporting period, but no conflicting evidence was found.…”

“…Term of Reference 4 (TOR4) required a review and assessment of the robustness and effectiveness of different types of geographical artificial or natural boundaries that are being used to define restricted areas. A predictive epidemiological model was used in the previous report (EFSA, ) to assess if spread through the wild boar populations with barriers in the modelled landscape were more similar to the spread observed from the ADNS data, than spread without the barriers. Based on this comparison in the model, it was not possible to demonstrate an effect of natural barriers on ASF spread in 2018.…”

“…In addition, the effectiveness of different artificial barriers that are used to separate wild boar were evaluated based on information found in the scientific literature. As for the previous report (EFSA, ), this was carried out by updating the literature review and new publications were identified, but the conclusions did not alter:…”

“…The extensive literature review (EFSA, ) to study the efficacy of different methods to reduce wild boar population densities to control ASF spread was updated in this reporting period to evaluate if the conclusions were still pertinent.…”