Distribution of Schmallenberg virus and seroprevalence in Belgian sheep and goats

A serological survey to detect Schmallenberg virus (SBV)-specific antibodies by ELISA was organized in the Belgian sheep population to study the seroprevalence at the end of the epidemic. One thousand eighty-two sheep samples which were collected from 83 herds all over Belgium between November 2011 and April 2012 were tested. The overall within-herd seroprevalence and the intraclass correlation coefficient were estimated at 84.31% (95% CI: 84.19-84.43) and 0.34, respectively. The overall between-herd seroprevalence was 98.03% (95% CI: 97.86-98.18). A spatial cluster analysis identified a cluster of six farms with significantly lower within-herd seroprevalence in the south of Belgium compared with the rest of the population (P = 0.04). It was shown that seroprevalence was associated to flock density and that the latter explained the presence of the spatial cluster. Additionally, 142 goat samples from eight different herds were tested for SBV-specific antibodies. The within-herd seroprevalence in goats was estimated at 40.68% (95% CI: 23.57-60.4%). The results of the current study provided evidence that almost every Belgian sheep herd has been in contact with SBV during 2011 and should be taken into consideration as part of comprehensive SBV surveillance and control strategies

A freedom from disease study: Schmallenberg virus in the south of England in 2015

In 2011–2012, northern European livestock faced a threat from a newly emerged virus, Schmallenberg virus (SBV), only a few years after a major outbreak of bluetongue serotype 8 (BTV-8). Like BTV-8, SBV is transmitted by Culicoides biting midges to ruminants and spread throughout Europe. SBV, however, spread faster, reaching the UK within three months of initial discovery. Adult ruminants show only mild, if any, clinical signs; however, infection of naive ruminants by SBV during the vulnerable period of gestation leads to abortions, stillbirths and fetal malformations. Although some data exist for the prevalence of SBV on UK sheep farms early in the outbreak, we have no information on its current status. Is SBV still circulating in the UK? To answer this, the authors designed a freedom from disease study across the southernmost counties of the UK. During autumn 2015, 1444 sheep, from 131 farms, were tested for antibodies against SBV by ELISA; 5 samples from 4 farms were twice found positive by ELISA but were later confirmed negative by virus neutralisation test. As the sheep were born between October 2014 and April 2015, the authors conclude that it is unlikely that SBV is still circulating in the south of England

Transmission study of Salmonella in pigs with 3 intervention strategies

In this study, the effect of 3 different intervention strategies on the transmission of Salmonella in pigs was evaluated: feed supplementation with coated calcium-butyrate salt, vaccination and acidified drinking water. Strategies were evaluated serologically and bacteriologically using an experimental in vivo seeder setup. Significantly higher antibody titers were detected in the groups with acidified drinking water and vaccination

The role of the infection status of sows on the assignment as Salmonella risk farm in the Belgian Salmonella control program

Salmonella surveillance and control programs arc generally based on results of samples taken from the fattening pigs and intervention measures are limited to the fattening unit. To evaluate the role of the sows in the assignment as Salmonella risk herd we compared the serological status from sows at risk herds to the status of sows at non-risk farms. From this study it is clear that the role of the sows and their serological Salmonella status is a potential influencing factor for the assignment of Salmonella risk farms in the Belgian Salmonella control program, which is principally based on sampling of fattening pigs. More insight in the role of the sow as a reservoir for Salmonella infections might help to define important intervention measures at pre-harvest stage

Bacteriological prevalence in finishing pig farms assigned as Salmonella risk farms by serological screening

The Belgian Federal Agency for the Safety of the Food Chain (FASFC) installed a National Salmonella surveillance and control program in pigs, the Salmonella Action Plan (SAP), which became compulsory by means of a Royal act in July 2007. Assignment as Salmonella risk farm is based on serological analysis of blood samples collected from the fattening pigs. The knowledge of prevailing serovars of Salmonella by bacteriological methods is essential to develop and/or evaluate the serological method. In 57% of all the assigned farms, based on serological screening (~ mean SIP-ratio\u27s), there is \u27firm evidence\u27 by bacteriological isolation. This suggests that a sufficient correlation is achieved at herd level in the first stage of the Salmonella Action Plan

How is Europe positioned for a re-emergence of Schmallenberg virus?

The Schmallenberg virus (SBV) caused a large scale epidemic in Europe from 2011–2013 infecting ruminants and causing fetal deformities after infection of pregnant animals. The main impacts of the virus were financial losses due to animal, meat and semen trade restrictions. Even though effective vaccines were produced, their uptake was never high. This along with the subsequent decline in new SBV infections and natural replacement of previously exposed livestock has resulted in a drop in the number of protected animals. Recent surveillance has found a large population of naïve animals currently present in Europe and the virus circulating at a low level. These changes in animal status in combination with favourable conditions for the insect vectors may open the door to the re-emergence of the virus and another large-scale outbreak in Europe. This review details the potential and preparedness for SBV re-emergence in Europe, discusses possible co-ordinated sentinel monitoring programmes both for ruminant seroconversion and the presence of virus in the insect vectors and provides an overview of the economic impact associated with diagnosis, control and the effect of non-vaccination