Schmallenberg Virus (SBV)

This is a new viral infection that effects ruminants (cattle, sheep and goats) and is transmitted by midges. It was first identified in November 2011 near the German town of Schmallenberg. The disease has been detected in 16 countries in Europe and was first reported in Ireland, in Cork, on 30th October 2012. SBV is transmitted by midges (Culicoides) which are normally active in Ireland between April and November.

Clinical signs and impact
Clinical signs in adult cattle during this period include fever, off food, reduced milk yield and sometimes diarrhoea. Animals typically recover within about 4 days (it generally moves through a herd within two to three weeks) and during this time they acquire immunity, which is believed to be life-long. However, if the animal is pregnant at the time it is infected abortions or the birth of deformed calves can result. Calves born alive may be ‘dummy calves’ with an inability to suckle. The critical period of pregnancy is 2-4 months for cattle. Examples of deformities include deformed limbs, stiff necks, curved spines and a shortened lower jaw.

Key point: Animals recover from infection within a few days and develop immunity but if pregnant when infected, abortions and the birth of deformed calves can result.

Treatment and control
There is no treatment or vaccine currently available for this disease but inactivated vaccines are being developed. Further spread to unaffected herds is very likely during the 2013 vector season but should have relatively little impact on non-pregnant livestock. It is generally impractical to attempt midge control measures except perhaps for breeding stock and it would be hoped that exposure of non-pregnant animals may in fact be beneficial pending the development of a vaccine as exposed animals develop strong immunity.

There are products that are active against Culicoides midges, the principle vector of transmission, that can be applied during the midge season (April to November) to reduce the risk of transmission, but they can only be regarded as an aid in control of the midges that transmit the virus. Since they are insecticides and not repellents, early season use to prevent midge populations developing will have most, if still limited, success.

Key point: Early season treatment, of breeding stock with products that are active against midges that spread the disease, is worth considering but is not 100% effective.

There is currently no evidence of any risk to humans and the condition is not a notifiable disease. Further information is provided on the Department of Agriculture’s website at www.agriculture.gov.ie

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