Concerns grow over avian flu in France

France's Agriculture Ministry has raised the country's risk level for avian flu from moderate to high after new cases of the highly contagious virus were detected.

The "high" risk level implies that all poultry should be kept inside on farms and additional security measures taken to avoid a spread of the disease.

Outbreaks have already been reported in Belgium, Germany and the Netherlands, and the first case in France was confirmed on a farm in the northwest Brittany region last week.

The virus, which strikes the digestive and respiratory organs of birds, tends to spread in fall and winter. In the Belgian town of Diksmuide, close to the border with France, a recent outbreak killed 95 poultry birds and caused the rest of the flock of 20,100 to be slaughtered.

Europe's worst-ever outbreak of the virus occurred last year, when 50 million birds were killed or culled across 37 countries.

In September, the United States banned poultry imports from France after the latter decided to vaccinate ducks against the virus, which is easily transmitted without visible symptoms.

From last year to spring this year, an outbreak in the US saw about 59 million birds culled in 47 states, and it had cost farmers around $3 billion, the USA Today reported.

The virus can be transmitted from animals to humans, either through direct contact with a contaminated environment or via another animal as an intermediate host, but there is no suggestion it can be transmitted between humans.

Earlier this year, Paul Digard, a professor of virology at The Roslin Institute at the University of Edinburgh, told Politico website that the virus' "shape-shifting abilities "were a major cause for concern.

"It's one of the fastest evolving things on the planet," he said, adding that the big fear was that if a person or an animal was infected with both avian flu and human flu, a new hybrid subtype might emerge, "and that could be the start of a pandemic".