Schmallenberg virus (SBV)Overview and scientific studies

Brussels, 08.04.2014Veldhuis A, Santman-Berends I, Gethmann J, Holsteg M,

Höreth-Böntgen D, Conraths F, van Schaik G, Elbers A, Bouwstra R, van der Heijden H, Mars M., Carp-van Dijken

S, van Wuijckhuise L, Witteveen G, van den Brom R, Luttikholt S, Lievaart-Peterson K, van Maanen C,

Vellema P

Start of Schmallenberg virus epizootic• November 18th 2011, Schmallenberg virus was

identified in dairy cows with a drop in milk production in cows in Northwestern Germany, and fever, drop in milk production and diarrhoea in the Netherlands, in August/September 2011.

• 25.11.2011: Maastricht: first case ofcongenital malformation reported to the Animal Health Service (GD)

Ovine congenital malformations

• 06.12.2011: second case: Zwolle• 07.12.2011: third case: Laren• 08.12.2011: Bodegraven• 09.12.2011: Zegveld• 09.12.2011: veterinary practitioners in the

Netherlands informed• 13.12.2011: contact with Belgium and Germany• 15.12.2011: Schmallenberg virus PCR+• 20.12.2011: made notifiable; 30 cases reported

SBV seroprevalence 2011/2012

Serosurvey in cattle, sheep and goats

•Gain insight in the spatiotemporal introduction of SBV in 2011, by testing sheep serum samples from early 2011•Archived serum samples from winter 2011/2012 were used•In-house ELISA (SE 98,8% / SP 98,8%)

SBV seroprevalence 2011/2012Results•Herd level prevalences: 95.5% in dairy cattle / 99.3% in non-dairy cattle / 97.1% in sheep flocks / 81.1% in goat herds •In dairy heifers, seroprevalence

increased with age•In sheep, seroprevalence was lower

in animals located in the coastal area•Most likely time of introduction:

mid-August 2011 (60% seropos. in Sept)

SBV in Dutch dairy herdsCase-control study ► Feb-Sept 2012

•Case herds (N=75): dairy herds with clinical signs in summer 2011 (likely due to SBV infection) + dairy herds that notified malformations in newborn calves

•Control herds (N=74): no clinical signs related to a SBV infection in adult cattle in 2011 + no remarkable change in reproductive performance + no malformations in newborns

Data collection•Herd visit ► (i) questionnaire by vet (ii) 70 serum samples

•Data on milk production / reproductive performance / mortality for 2011•Insight in vertical transmission of SBV

– Post-mortem investigation of stillborn / aborted / malformed calves

•Development of maternal immunity– Follow-up of offspring of cows that showed clinical signs in summer 2011

SBV in Dutch dairy herds

SBV in Dutch sheep flocks• Risk factors for malformations and impact on

reproductive performance and mortality• A case-control study design • The percentages of stillborn lambs or lambs that

died before weaning, repeat breeders, and lambs with abnormal suckling behaviour were significantly higher in case flocks compared to control flocks. However, effects limited.

• Risk factors: start of the mating season before and in August 2011, purchase of silage and flocks with one or more dogs

Impact on productivity of dairy cattle

Thanks to many hard working colleagues at GD-Deventer and CVI-

Lelystad