An outbreak of bird flu in west Germany led to the slaughter of about 30,000 ducks on a farm in the Guetersloh area. The disease, also known as highly pathogenic avian influenza, has resulted in the culling of hundreds of millions of birds in the past, particularly in Europe during autumn and winter. In response to new cases of bird flu, France has raised the risk level to 'high' and ordered a third dose of a vaccine for ducks in at-risk areas as well as requiring poultry farms to keep birds indoors to prevent further spread of the virus.