Project

SBV seroprevalentie GD (English)

This study aimed at estimating the Schmallenberg virus (SBV) seroprevalence in dairy heifers, non-dairy adult cattle, sheep and goats in the Netherlands after cessation of SBV transmission at the end of 2011. Archived serum samples from ruminants submitted to the GD Animal Health Service for monitoring purposes between November 2011 and March 2012 were selected and tested for presence of SBV-specific antibodies using an in-house ELISA. Multivariable analyses were carried out to describe the relationship between potential risk factors and the ELISA test outcome S/P%. Further, an attempt was made to gain insight in the spatiotemporal introduction of SBV in the Netherlands in 2011, by testing sheep serum samples from 2011.

From November 2011 on, SBV was found to cause an outbreak of congenital malformations in lambs and goat kidsand newborn calves. In the Netherlands, clinical signs of SBV infection were notifiable between December 20th,2011 and July 6th, 2012, i.e. malformations in newborn ruminants had to be reported to the authorities. To detect antibodies in blood samples, a virus neutralization test (VNT) has been developed, which has been used for a first seroprevalence estimate in dairy cattle by the Central Veterinary Institute (Elbers et al., 2012). However, to gain more insight in the level of SBV infection in both ruminants (dairy and non-dairy) and small ruminants in the Netherlands, as well as the geographic spread, a large-scale seroprevalence study was needed.

Objectives

The primary objective of the current study was to determine SBV seroprevalence in the Netherlands (by means of an SBV-ELISA) to gain insight in the true rate of infection in cattle, sheep and goats after cessation of viral circulation in 2011. By doing so, a better understanding of the potential damage following overwintering of SBV into a new vector-active season, indicated by the (remaining) proportion of naïve animals, was established. The second objective was to identify risk factors for SBV infection, in terms of the magnitude of antibody responses (sample to positive ratio; S/P%). Finally, an attempt was made to identify the spatiotemporal introduction of this new virus in the Netherlands by determining the pattern of seroprevalence in archived sheep serum samples.

Results

Results and opportunities: Animal seroprevalences will be estimated in dairy heifers, in adult non-dairy cattle, in sheep and in goats. Multivariable analyses will be carried out to describe the relationship between potential risk factors and the ELISA test outcome. Furthermore, an attempt will be made to gain insight in the spatiotemporal introduction of SBV in the Netherlands in 2011, by testing sheep serum samples from 2011.

Methodology and time table

Archived serum samples from ruminants submitted to the GD Animal Health Service for monitoring purposes between November 2011 and March 2012 were selected and tested for presence of SBV-specific antibodies using an in-house ELISA. Testing will be finished by the end of 2012, preliminary report will be produced by Spring 2013, and final report before the summer of 2013

Publications