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What Links Pig Carcass Downgrades with Bluetongue, Schmallenberg?

21 March 2012, at 9:41am

ANALYSIS - The answer is biting midges of the family, Culicoides, writes senior editor, Jackie Linden. Bites from these midges caused pig carcasses in Scotland to be downgraded last year and the same family of insects transmits the virus that causes bluetongue and Schmallenberg diseases in ruminants.

Over the last few years, two new viral diseases have emerged, hitting cattle and sheep in Europe, causing significant losses and devastation on some farms. Bluetongue spread from South Africa, reaching northern Europe in 2006. In November 2011, what has since become known as Schmallenberg disease – after the German town in which the virus was first identified in cattle – has spread across northern Europe.

The ravages of bluetongue have been brought under control by vaccination but Schmallenberg is currently causing significant losses in the European sheep flock during the current lambing season. Ewes infected during early pregnancy last year are now giving birth to deformed lambs and ewes are being lost as the result of lambing difficulties. The impact on the cattle industry remains speculation as the main calving season in northern Europe is yet to start.

These devastating diseases are thought to have emerged as a result of climate change and changing patterns of pathogens and vectors, which, in the case of both bluetongue and Schmallenberg diseases, are biting midges of the family, Culicoides.

There is no evidence that non-ruminants such as pigs are affected by either of these viruses and the same species of midge are not necessarily involved. However, the latest Emerging Threats Quarterly Report from the AHVLA in the UK [click here to see the report] mentions that SAC reported skin lesions suspected to be due to biting midges (Culicoides obsoletus and Culicoides impunctatus) causing significant losses in the abattoir due to condemnations.

Of all insects caught in traps, the report says these species comprised 25 per cent and six per cent, respectively. Both these species are known to feed on pigs. No other species capable of biting pig skin were detected. Stomoxys species flies are suspected of causing skin lesions in other parts of UK but were not found in Scotland.

Further Reading

- Find out more information on Schmallenberg disease by clicking here.