Control and eradication of Classic Swine Fever in wild boar

Abstract

SummaryClassical swine fever (CSF) is a disease that has been causing major socio-economic damages in the EU during the last decades. Although considerable progress has been made in the eradication and prevention of the disease, the threat for an epidemic still exists.The virus is endemic in the wild boar population of several member states (MS). Wild boar cannot be managed as domestic pigs. Hunting and vaccination have been tentatively used in order to stop transmission by reducing the number of susceptibles. Oral vaccination of wild boar with modified live vaccine based on the C-strain (the only suitable) is used; this vaccine does not allow serological differentiation between vaccinated and infected animals.The aim of the control measures for CSF in wild boar is to reduce the risk of transmission to domestic pigs, to prevent an "endemic phase evolution" or to reduce the endemic phase duration.In order to support and to improve the control and eradication measures as regards CSF in wild boar, EFSA was requested by the Commission to provide scientific advice on the efficacy of the available surveillance, hunting and vaccination measures to control and eradicate CSF in feral pig populations (wild boar), considering the possible use of new diagnostic tests and vaccines.In order to reply to the mandate data were collected from MS through two questionnaires (CSF vaccines, hunting practices and CSF vaccination in wild boar). Data were also extracted from the EU CSF wild boar data base, after requesting permission from the participating MS.Considering that the data received were rather limited and not comparable, the WG decided to use a model in order to fill the gaps in the available knowledge. For the evaluation of the efficacy of CSF control in wild boar a continuous metapopulation compartmental model developed in an EU research project (FP6-5015599-CSFVACCINE&WILDBOAR) was applied.Although the disease manifests in the same manner in both domestic pig and wild boar it is more difficult to identify in wild boar because clinical monitoring of these is hardly possible. Wild boar found dead constitutes the main alert sign of CSF. Hunters and gamekeepers should be instructed to report the finding of each dead wild boar to the competent authority at all times. In case of high-risk situations, a passive surveillance should be complemented by an active serological surveillance. The active sampling of wild boar is not as efficient as in domestic pigs considering that hunting is the sole practical system to obtain samples and that the aim of hunting is quite different.Consequently, the sample size is not controlled by authorities and fits rarely the aim of the survey in terms of detecting the presence of disease at a certain level. In addition, the interpretation of serological results is confounded by maternal derived antibodies (until the 6th month of age), vaccination and the sampling quality.There is no definition at EU level of spatial and temporal units for surveillance, neither for criteria defining a disease free wi...

Estimation of the Lethality Rate, Recovery Rate, and Case Fatality Ratio of Classical Swine Fever in Japanese Wild Boar: An Analysis of the Epidemics From September 2018 to March 2019

“…( 43 )], we assumed the possible range of the annual mortality rate to be 0.10–0.50. Our estimate of the recovery rate differed from that reported previously ( 21 ). We also conducted a sensitivity analysis for the estimated CFRs with the change in recovery rate ranging around our estimate; from 0.05 to 0.25 per year (0.001–0.006 per week).…”

“…Sampling surveys are easier to conduct compared to the following-up survey of the infected wild boar. Another way to estimate the CFR is to estimate from the time-series data of infected and dead wild boar using a mathematical model describing the transmission process of infectious diseases (e.g., Susceptible-Exposed-Infectious-Recovered [SEIR] model) ( 21 , 28 ).…”

“…Based on previous modelling studies of CSF in wild boar populations ( 21 , 29 ) and feral pigs ( 28 , 36 ), the transmission dynamics of CSF can be written as follows:…”

Relevance of Indirect Transmission for Wildlife Disease Surveillance

“…The 900 grid cells were randomly initialized with integer values of local breeding capacity in range 0, …, 3. Breeding capacity was scaled to result in an average wild boar density of 5 hosts/km 2 in January, i.e., before the reproductive season (68, 69). The average population size in January was 18,000 individuals.…”

Seasonal host life‐history processes fuel disease dynamics at different spatial scales

“…The European wild boar (Sus scrofa L.) is an ideal model system to investigate disease invasion and persistence due to its importance in spreading diseases to livestock and vice versa, combined with its social behaviour and the increase in numbers all over Europe (Bieber & Ruf, 2005;EFSA, 2009;Ruiz-Fons, Segalés, & Gortázar, 2008;Sáez-Royuela & Tellería, 1986). For example, the recent spread of African swine fever (ASF) in Europe is linked to movement of wild boars, but the reasons for the ongoing circulation are still unclear (Gavier-Widén et al, 2015;Podgórski & Smietanka, 2018;Schulz, Staubach, & Blome, 2017).…”