Antibodies to Schmallenberg virus found in deer



Evidence of antibodies to Schmallenberg virus in deer: After calling on the public to be alert to signs of infection with Schmallenberg virus is wild animals DWHC presents results from investigations in 2012.

The question

Schmallenberg virus (SBV) is an orthobunyavirus that was discovered at the end of 2011. It causes disease characterized by congenital abnormalities in cattle, goats and sheep .
The DWHC wanted to determine whether:
1) wildlife in the Netherlands could also be infected by the virus?
2) infection with this virus could cause disease in wildlife species?

Methods

In order to address the question of whether or not wildlife in the Netherlands could/had been infected with the virus, blood and bloody-fluids were collected from the 29 deer submitted to the DWHC for post-mortem investigation in 2012. Antibody testing (virus neutralisation testing) of these samples was performed by the Central Veterinary Institute (CVI) in Lelystad. In cattle and sheep, a VNT-test result greater than 8 or 16, respectively is indicative of infection (at some point) with the virus.

In order to assess whether or not infection also causes disease in wildlife species, the public (and in particular wardens and hunters) were asked to submit any young animals with evidence of malformity, and adult animals with non-progressing pregnancy and/or signs of diarrhoea. In the first six months of 2012, post-mortem investigation was performed on eight such animals; the presence of the virus in different tissues from these animals was investigated using molecular techniques (PCR) at the CVI.

The results

VNT-values exceeding 16 were found in 15 of the 29 deer (52%); five animals (17%) had VNT-values of 8-16 and the remaining nine (31%) had VNT-values less than eight. These results are depicted on the map.

Viral genetic material was not detected by PCR in any of the tissues from the eight animals with possible signs of SBV infection.

kaart met schmallenbergvirus VNT-titer

Conclusion and interpretation

  1. These findings suggest that it is very likely that deer can be infected with SBV;  However, these results are based on the premise that the VNT reference values for cattle and sheep are valid in deer. Our results are in-line with the report that the majority of deer tested in Belgium in December 2011 had antibodies to SBV  (Linden et al, 2012).
  2. Similar to reports from studies in neighboring countries, it remains unclear whether or not infection causes disease and impairs reproductive performance in deer.

Given the remaining uncertainties the DWHC will continue to monitor SBV in deer and requests that all suspect cases be reported to the DWHC (030-2537925).

References

Linden A, Desmecht D, Volpe R, Wirtgen M, Gregoire F, Pirson J, Paternostre J, Kleijnen D, Schirrmeier H, Beer M, Garigliany MM. Epizootic spread of Schmallenberg virus among wild cervids, Belgium, Fall 2011. Emerg Infect Dis. 2012 Dec;18(12):2006-8.