The first confirmed cases of Schmallenberg virus (SBV) have been found in 2024 in sheep in Co. Wexford.
Figures provided to Agriland by the Department of Agriculture, Food and the Marine (DAFM) indicate that SBV positive test results were recorded last month.
SBV is not notifiable, and it is possible many more cases were never taken to a laboratory for confirmation and therefore have gone undetected.
Year No. of PCR tests for Schmallenberg virus RNA Cases of Schmallenberg virus Livestock species testing positive Counties where cases identified 2019 290 0 – – 2020 203 0 – – 2021 239 0 – – 2022 236 0 – – 2023 267 1 Cattle Tipperary 2024 YTD [31/01/2024] 5 2 Sheep Wexford
As the table above indicates, there have been five PCR (polymerase chain reaction) tests thus far in 2024.
With two confirmed cases already this year, it is already more than the total confirmed cases of SBV in 2023, which saw one confirmed case detected in cattle in Co. Tipperary.
Prior to 2023, the figures provided by the DAFM indicate there has not been a confirmed case of SBV since 2018.
SBV first hit Irish shores in 2012. It was transported by midges and affected flocks mainly in the southern and eastern parts of the country.
In cattle, SBV is associated with fever, milk drop, diarrhoea, as well as abortion and deformed foetuses.
In sheep and goats, it is known to cause abortion and deformed lambs. The congenital deformities which occur include torticollis (twisted neck), arthrogryposis (limbs bent and locked), shortened lower jaws and hydranencephaly (abnormalities with excess fluid in the brain).
The critical period for the development of congenital deformities is when infections occurs between 28-56 days in sheep and 62-170 days in cattle.
Schmallenberg virus in the UK
Cases of SBV in newborn lambs are being widely reported by vets in areas of the United Kingdom (UK).
The National Sheep Association (NSA) acknowledged an “emerging spike in confirmed cases of Schmallenberg virus”.
NSA chief executive Phil Stocker said “it is extremely concerning to hear of proven (and assumed) cases of this virus.
“These are from naive animals that were bitten by infected midges back in the autumn during their early stages of pregnancy.
Stocker said: “NSA would urge all working with sheep and cattle at these times to be vigilant to the signs of SBV and to contact their vets should they suspect the presence of any cases on their farms.”
If ruminant animals should become infected when pregnant, it can lead to abortion or malformations in the foetus.