Schmallenberg virus (SBV) is transmitted by vector (biting midges) during the vector active season which, in most years in Ireland, extends from the beginning of April through to the beginning of December. This virus causes mild transient disease manifesting as a drop in milk production, fever and sometimes diarrhoea in adult cattle. When infection occurs in animals that are not pregnant, the impact is very limited. However if ruminant animals are infected during the early stages of pregnancy, they may subsequently abort or give birth to malformed offspring.
It would be impractical to attempt midge control measures, except for valuable breeding stock. Exposure of non-pregnant animals to the virus may, in fact, be beneficial pending the development of an effective vaccine. Exposed animals develop a strong immunity and are unlikely to suffer any ill-effects if exposed to the virus on a subsequent occasion. If this viral infection becomes endemic, the ill-effects are likely to be confined to younger animals and cows and ewes that have not been previously exposed. Based on Australian experience in vaccinating against a similar virus/disease (Akabane virus infection), the expert view is that vaccination is likely to be an effective tool in control of the SBV infection. The development of a vaccine is in progress and my Department will continue to monitor developments closely.
Meanwhile, farmers are advised to contact their veterinary practitioner if they encounter cases of aborted foetuses or newborn animals showing malformations or nervous signs and also in cases where lambs or calves cannot be delivered naturally.