New orthobunyavirus detected in cattle in Germany, Switzerland and France
The Friedrich-Loeffler-Institut and Swiss IVI have identified a novel Simbu-group orthobunyavirus in sick dairy cows. The midge-borne pathogen causes fever, diarrhoea and a sharp drop in milk yield, and authorities expect further spread before the insect season ends in November.
Virus identification
On 3 August 2026, the Friedrich-Loeffler-Institut (FLI) on the island of Riems and the Swiss Institute of Virology and Immunology (IVI) confirmed the detection of a novel orthobunyavirus belonging to the Simbu serogroup in sick cattle. The FLI examined four samples from farms in Baden-Württemberg, southern Germany, while the IVI analysed samples from affected Swiss herds. French authorities have reported matching findings. The virus, transmitted by blood-sucking midges, is new to Europe; Simbu-group viruses are otherwise found mainly in Africa, Asia and Australia.
Symptoms and affected animals
Infected cattle develop fever exceeding 40 degrees Celsius, diarrhoea, loss of appetite and a sharp decline in milk yield. In dairy cows the drop in production is described as massive. The disease episode on a farm lasts roughly 14 to 21 days, according to the IVI. Pregnant cows are at risk of stillbirths and calf malformations. Sheep and goats are also susceptible. The FLI notes that the full pathogenic potential of the virus is not yet known.
Transmission and seasonality
The virus is carried by Culicoides biting midges, also called gnats or Bartmücken. The midge season in central Europe runs until the end of November, and the FLI warns that further, possibly rapid, spread must be expected while the insects remain active. It is unclear whether the current heatwave has increased the vulnerability of cattle; high temperatures can make high-yielding dairy cows more susceptible to disease.
No danger to humans
The IVI stressed that the disease is not classified as a notifiable animal epidemic under Swiss law.
It is not a highly contagious disease.
Simbu serogroup viruses are generally not considered zoonotic and, based on current knowledge, pose no relevant infection risk to humans.
Echoes of Schmallenberg
The new virus belongs to the same group as the Schmallenberg virus, which reached Germany in 2011 and was detected in Switzerland a year later. That outbreak caused stillbirths and congenital malformations in calves, lambs and goat kids, affecting more than 2,000 farms in Germany alone. Whether similar reproductive damage will occur with the newly identified virus requires further investigation, the FLI said.
Next steps
The IVI has urged livestock keepers to contact a veterinarian immediately if they observe unspecific symptoms such as fever, diarrhoea or a sudden drop in milk production. The FLI is continuing its laboratory characterisation of the virus. With the midge season lasting until late autumn, veterinary authorities in Germany, Switzerland and France are on alert for additional cases.
