|The unavailability of a fully authorised Schmallenberg virus (SBV) vaccine has been remedied by the introduction of Zulvac® SBV from Zoetis. It is a new SBV vaccine licensed for use in cattle and sheep in two doses at a three week interval, the second at least two weeks before mating. Supplies are available immediately.
Duration of immunity is six months in cattle and seven in sheep. At the recommended vaccination timing, this covers the window of susceptibility during pregnancy; in sheep from day 28 to 56, and days 70 to 150 in cattle. Animals infected during these periods are at risk of malformed offspring and subsequent stillbirth.
Vaccination combined with insecticidal measures to control the midge vector remains the most effective way of protecting the population, and ensuring a more unified level of immunity, according to Zoetis vet Carolyn Hogan.
“Although SBV is now considered to be an enzootic pathogen in England and Wales, there is plenty of evidence that seroprevalence at farm level – particularly on sheep farms – varies. As immunity wanes, the proportion of herds and flocks naïve to SBV and at risk via introduction of naïve replacements increases,” she explains. “So the risk of reinfection in assumed enzootic areas is potentially underestimated.
“Culicoides midges, the SBV vector, are widespread in Europe and move easily between farms and regions, allowing rapid spread of infection.”
Ms Hogan says that whilst there have been no confirmed diagnoses of congenital abnormalities in calves or lambs from APHA in 2014 or 2015, unconfirmed anecdotal cases have been reported.
“We do not know whether our ruminant population is immune or susceptible and neither do we know if another SBV challenge will appear. Vaccination remains the most effective way of ensuring valuable livestock are protected.”