THE CHALLENGE OF DETECTING CLASSICAL SWINE FEVER VIRUS CIRCULATION IN WILD BOAR (SUS SCROFA): SIMULATION OF SAMPLING OPTIONS

Abstract

Classical swine fever (CSF) is one of the most important viral diseases of domestic pigs ( Sus scrofa domesticus) and wild boar ( Sus scrofa ). For at least 4 decades, several European Union member states were confronted with outbreaks among wild boar and, as it had been shown that infected wild boar populations can be a major cause of primary outbreaks in domestic pigs, strict control measures for both species were implemented. To guarantee early detection and to demonstrate freedom from disease, intensive surveillance is carried out based on a hunting bag sample. In this context, virologic investigations play a major role in the early detection of new introductions and in regions immunized with a conventional vaccine. The required financial resources and personnel for reliable testing are often large, and sufficient sample sizes to detect low virus prevalences are difficult to obtain. We conducted a simulation to model the possible impact of changes in sample size and sampling intervals on the probability of CSF virus detection based on a study area of 65 German hunting grounds. A 5-yr period with 4,652 virologic investigations was considered. Results suggest that low prevalences could not be detected with a justifiable effort. The simulation of increased sample sizes per sampling interval showed only a slightly better performance but would be unrealistic in practice, especially outside the main hunting season. Further studies on other approaches such as targeted or risk-based sampling for virus detection in connection with (marker) antibody surveillance are needed.

A Simulation Model to Determine Sensitivity and Timeliness of Surveillance Strategies

“…Our study showed that passive surveillance alone would not be sufficient to meet the requirements of Commission Decision 2002/106/EG for infection detection. Although limited passive surveillance data were available for this study, these findings confirm the results of previous studies (Comin et al., ; Sonnenburg et al., ), which found that passive surveillance on its own is not enough to detect a disease outbreak reliably.…”

“…Sonnenburg et al. () also simulated different surveillance approaches for CSF in wild boar in times of disease freedom; however, they only focused on detection probability.…”

“…As shown by Sonnenburg et al. (), the informative value of a surveillance strategy depends on the chosen time period of sampling and on the size of the area. Therefore, our model may be easily adapted to other scenarios using other data sets.…”

“…Similar to the study of Sonnenburg et al. (), where the possible impact of changes in sample size and sampling intervals on the probability of classical swine fever (CSF) detection was modelled, the present model is non‐epidemic. In such a non‐epidemic model, the spread of disease is not taken into account, but a static snapshot of an epidemic is considered.…”

Monitoramento sanitário para peste suína clássica em suídeos asselvajados no Estado do Rio Grande do Sul, Brasil, de 2014 a 2018

“…Por ser altamente transmissível, apresentar grande poder de difusão e especial gravidade, traz prejuízos econômicos e sanitários graves, o que pode dificultar ou impossibilitar o comércio internacional de animais e produtos de origem animal (BRASIL, 2004). Neste sentido, populações de suídeos asselvajados, caso estejam infectados, podem ser a principal fonte de introdução de PSC na população de suídeos domésticos (SONNENBURG et al, 2016) (Fig. 1).…”