Dutch poultry farmers were keeping their birds indoors on Friday to comply with a government order after a highly contagious form of bird flu was found in two dead swans this week.
A spokeswoman for the Agriculture Ministry said that it was not yet clear how long the order will be enforced but noted that no cases have yet been found among commercial fowl.
Poultry is a 1.6 billion euro ($1.9 billion) industry in the Netherlands, Europe's largest exporter of chicken meat and eggs, employing 10,000 people on 2,000 farms.
Researchers from The University of Wageningen found a highly pathogenic form of the H5N8 virus in the swans after previous swan infections in Russia and Israel this year.
"The virus was probably introduced to the Netherlands through other (migratory) bird species, after which local bird populations became infected. This suggests that the virus is circulating locally among wild birds in the Netherlands," the researchers said.
Eric Hubers, a poultry farmer and spokesman for the Netherlands' LTO agricultural industry group, said he supports the government's order.
Economic damage from the move will depend on how long the birds must remain indoors, he said, because birds will no longer qualify for the more lucrative "free range" designation if they must be kept indoors for more than 16 weeks.
He said the country had learned to shelter birds indoors and prevent transmission between farms after the 2003 bird flu outbreak in which 30 million Dutch chickens were culled. Outbreaks in 2014, 2016 and 2017 were contained with only modest consequences.
Last month the European Union urged countries to step up surveillance against possible outbreaks of avian flu among wild and domestic birds. [nL8N2GR35E]
($1 = 0.8442 euros)
(Reporting by Toby Sterling; Editing by David Goodman)
