Several outbreaks of severe bird flu in Europe and Asia have been reported to the World Organisation for Animal Health (OIE) sparking fears the virus is spreading quickly again.
The poultry industry has been put on alert following previous outbreaks of highly pathogenic avian influenza, commonly called bird flu, resulting in the culling of tens of millions of birds.
The increase in outbreaks have attracted the attention of epidemiologists because the virus can be transmitted to humans, the Guardian reports.
So far this year China has reported 21 cases of humans being infected with the H5N6 subtype of avian influenza - this is more cases than in the whole of 2020.
On Monday the OIE cited a report from the South Korean authorities which revealed an outbreak at a farm of around 770,000 poultry in Chungcheongbuk-do.
All the animals on the farm were slaughtered.
The OIE said Japan has reported an outbreak at a poultry farm in the north-east of the country which is the first in the 2021 winter season.
The outbreak, of the H5N8 strain, was confirmed in a statement last week by Japan’s agriculture ministry.
Norway reported an H5N1 bird flu outbreak in the Rogaland region in a flock of 7,000 birds, the OIE said.
Bird flu circulates naturally among wild birds.
The disease can be spread to poultry and other captive birds and when they migrate to the UK in winter from mainland Europe.
In Belgium all poultry must be kept indoors after a highly pathogenic variant of bird flu was identified in a wild goose near Antwerp.
The new rule came into force on Monday to tackle the spread of bird flu.
Similar rules are already in place in neighbouring France and the Netherlands.
A bird flu prevention zone was declared across Great Britain earlier this month.
This means all bird keepers must adhere to to strict biosecurity measures after a flock of poultry was slaughtered near Dundee in Scotland in response to a bird flu outbreak.
UK Chief Veterinary Officer Christine Middlemiss said: "We have declared an Avian Influenza Prevention Zone across Great Britain, so whether you keep just a few birds or thousands, it's vital that all bird keepers take action to introduce higher biosecurity standards on their farm or small holdings."
Last week a farm in Lancashire became the latest place in the UK to record an outbreak of bird flu.
Officials declared a temporary control zone around the affected site in Salwick, near Preston.
Bird flu can transmit to humans in rare cases if the touch infected birds, their droppings or bedding, or while preparing infected poultry for cooking.
People have been warned not to pick up sick or dead birds in order to prevent the disease spreading further.
