A new orthobunyavirus identified in cattle in Switzerland

A new orthobunyavirus of the Simbu serogroup has been identified in samples taken from sick cattle in Switzerland, Germany and France. Its presence was confirmed by the Institute of Virology and Immunology.

The virus is transmitted by blood-feeding midges. In affected animals it causes fever above 40 degrees, a sharp fall in milk production, loss of appetite and diarrhoea. On the Swiss farms concerned the illness lasted between 14 and 21 days.

Assessing the risk

According to the Friedrich-Loeffler Institute in Germany, on current knowledge the virus poses no significant infection risk to humans. The authorities nonetheless acknowledge the need for further investigation.

The new agent shows genetic similarity to the Shamonda virus and belongs to the same group as the Schmallenberg virus, detected in Switzerland in 2012.

The German institute notes that infections contracted during pregnancy can cause abortions, death of the foetus and serious congenital malformations. That is the aspect weighing most heavily on livestock farms, because it affects the next generation of animals.

Rapid spread is expected. The insects that transmit the disease remain active until November, leaving several more months of exposure in the current season.

For livestock farmers the practical difficulty lies in recognising the symptoms. They overlap with those of other conditions and with this summer's heat stress, and confirmation requires laboratory analysis of samples taken from the animals.

Swiss milk producers describe a critical situation. Low milk prices are compounded by drought, heat stress, sick animals and a shortage of hay, a combination that puts the survival of some farms under pressure.