The number of cases of Schmallenberg virus (SBV) have been rising across the UK. SBV is a viral disease that affects cattle, sheep and goats and was first detected in August 2011 in Germany. In the 6 weeks to January 2024, APHA confirmed 63 cases of SBV; the majority of which were detected in stillbon lambs.
SBV is not transmitted animal to animal but is spread via midges which are more active in the warmer wetter months. The recent rise is thought to be due to the warmer weather experienced in the Autumn of 2023.
Alongside a growing number of cases in the South of England and the Midlands, SBV has also been detected in Carmarthenshire, Ceredigion and Pembrokeshire.
SBV often presents as late abortions or birth defects, however it is important to recognise that not all cases of foetal abnormality will be caused by SBV. Foetal deformities are more prone in days 25-50 of the sheep gestation period, and days 62-180 in cattle. Older foetuses are able to clear the virus. SBV corrupts the foetal nerve tissue, which leads to brain and spinal cord abnormalities, as well as other issues with muscles and the skeleton. Common abnormalities include bent limbs, fixed joints, fused neck and legs and nervous signs such as uncoordinated movement, recumbency, inability to suck and convulsions. In adult animals, clinical signs include reduced milk yield, loss of body condition, loss of appetite and diarrhoea. Acute disease can last from 2 to 6 days and infected animals can quickly develop immunity to this virus.
No compensation schemes exist for infected stock and there is not a compulsory programme of culling infected stock. Due to the fact that the majority of SBV diagnosis is via newborn animals, movement restrictions would not be effective in controlling the disease as the infection would likely have occurred months prior to disease confirmation.
A vaccine against SBV is not currently commercially available, however the situation could change if more cases are identified. Although SBV is not a notifiable disease, the FUW continues to stress that farmers should familiarise themselves with the clinical signs of the disease in order to report suspicious cases to APHA for testing as part of the enhanced surveillance programme for this disease.